CN114580124B - Design method of variable-section uniform air supply pipeline of rail transit vehicle - Google Patents
Design method of variable-section uniform air supply pipeline of rail transit vehicle Download PDFInfo
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Abstract
The invention discloses a design method of a variable cross-section uniform air supply pipeline of a rail transit vehicle, which comprises the following steps: s1, dividing air conditioner partitions, and determining necessary parameters and limiting conditions of air supply pipeline design; s2, calculating the wind speed v r of a wind pipe with the smallest section of the air supply pipeline; s3, the number of pipe sections divided by the variable cross section air pipe is assumed to be n; s4, calculating the minimum width w omin of the air outlet; s5, calculating the minimum sectional area S 0min of the variable-section air pipe section 0; s6, calculating the minimum conveying power delta P emin of the air supply branch pipeline; s7, calculating the width w o of the air outlet; s8, calculating the sectional areas S i, the heights H i and the widths W i of the sections of the variable-section air supply pipeline. The invention can be used for not only designing the variable cross-section air supply pipeline of the ventilation air-conditioning system of the planned vehicle, but also evaluating the variable cross-section air supply pipeline of the ventilation air-conditioning system of the finished vehicle. The invention can also be used in other engineering fields.
Description
Technical Field
The invention belongs to the field of design methods of ventilation and air conditioning engineering, and particularly relates to a design method of a variable cross-section uniform air supply pipeline of a rail transit vehicle.
Background
In a rail transit vehicle air conditioning system, an air supply pipeline is an intermediate link connecting an air processing unit and a passenger compartment of a carriage. Whether the designed air supply quantity can be uniformly fed into the passenger room is important to realizing reasonable airflow organization distribution of the passenger room and guaranteeing the air quality of the passenger room. Regarding uniform air supply of rail transit vehicles, foreign published technical results are relatively few, and China tries to develop actively while introducing foreign technologies.
Literature one (Chen Jianyun, cang Jianbin. Subway train air conditioner uniform supply duct overview [ J ]. Refrigeration, 2017, 36 (141): 53-59.) states: at present, the main types of air supply pipelines adopted by rail transit vehicles at home and abroad are 4: circular pipe type air supply, large-section quasi-static pressure air supply, strip seam type static pressure air supply and novel variable-section air supply. The application and research status of various types of air supply pipelines are as follows:
(1) The circular pipe type air supply pipeline is an air pipe which determines the pipe diameters of different pipe sections to meet the air supply requirements of different positions through detailed resistance calculation and tests section by section. Document two (Long Jing, wang Shuao. Analysis of supply air duct of air conditioning system of subway vehicle [ J ]. Electric locomotive and urban rail vehicle, 2004, 27 (4): 40-42.) states that: this type of ductwork is used in many applications in foreign rail transit vehicles, such as: vienna subway, melbourne subway, neolumbo subway, oslo subway. However, the whole design, manufacture and construction process are complex, and only individual circuits of the domestic subway adopt the air-like duct, such as: guangzhou subway line three and Shanghai pearl line second phase.
(2) The large-section quasi-static pressure air supply pipeline is based on the principle that the cross-sectional area of an air pipe is large enough, dynamic pressure in the air pipe is small, static pressure is large, and change along the path is small, so that the uniform air supply-like air pipe with the same cross section is realized. The large-section quasi-static pressure air supply pipeline is suitable for vehicles with large roof space, such as railway passenger cars and subway A-type vehicles. The third literature (week survival, city sword, design analysis of air duct of domestic subway type vehicle air conditioning system [ J ]. Urban rail traffic research, 2008, (9): 36-39.) introduces the structural characteristics and design method of air duct of domestic A type vehicle adopting static pressure principle, and the further numerical simulation result shows that: because of the limitation of the size of the A-type vehicle, the air duct is not static pressure in a complete sense, and thus the uniformity of air outlet is adversely affected.
(3) The strip slit type static pressure air supply pipeline is an improvement on the metro vehicle air supply pipeline by referring to the design thought of large-section quasi-static pressure air supply of a railway passenger car. Fourth (Wang Shuao, see the development of uniform supply ducts for air-conditioned passenger cars [ J ]. Railway vehicles, 1992, (8): 112-114.) states that: most domestic metro vehicles generally adopt a strip-slit type static pressure air supply pipeline, for example: subway vehicles in cities such as vinca, dalian, beijing, tianjin, nanjing and Shanghai. The research results of the performance research of a static pressure uniform air supply channel of a passenger car air conditioner and the inducer (Yang Wan, the development of Qingdao: qingdao institute of construction engineering, 2002), the development of a six (Liu Yang, yikou, li Yingming) air supply uniformity design of an air supply channel system of a subway vehicle (J), electric locomotives and urban rail vehicles, 2011, 32 (1): 48-50), the development of a seven (Cang Jianbin, wang Xiaodong, shiyi, etc., show that the uniform air supply channel for the subway train is CN201020298338.7[ P ].2011-07-20 ]): the cross section area of the air duct cannot be large enough due to the limitation of the size of an actual subway vehicle, and the air duct cannot realize static pressure air supply in a real sense. In practical engineering, the strip-slit type static pressure air supply pipeline has to improve the air supply uniformity by changing the shape and the size of an air outlet or arranging a blocking body in an air duct. Therefore, certain difficulties are brought to design, manufacture and construction.
(4) The novel variable cross section air supply pipeline is of an air pipe type which can ensure that the dynamic pressure difference overcomes the resistance and the static pressure of the pipeline is kept unchanged by changing the cross section area of the air supply pipeline, thereby realizing uniform air supply. The air supply pipeline is more suitable for rail transit vehicles with limited sectional areas, particularly B-type vehicles and C-type vehicles, but the design difficulty is higher. With the development of CFD technology, the variable cut blast pipe is studied in the literature eight (Wang Liu. Air-conditioning blast duct of subway train and optimization study of air flow organization in passenger room [ D ]. Wuhan: university of technology in China, 2008.), the literature nine (Ma Yingong. Numerical simulation and optimization of air-out performance of air-conditioning blast duct of subway train [ D ]. Wuhan: university of technology in China, 2008.), the literature ten (Su Weihua, wu Fan, zhang Guoliang, etc.. The optimization study of variable cross-section duct internal structure of subway train [ J ]. Instructions of railway science and engineering, 2021, 18 (8): 2137-2144). However, the past research results have the following defects: : (a) It is impossible to determine whether the air volume borne by the air supply duct is reasonable. (b) The baffle bodies such as the spoiler or the guide plate are additionally arranged in the pipeline, and the advantage of uniform air supply with variable cross section is not fully exerted. (c) The selection of the cross-sectional dimension and the variation ratio is random and empirical, and cannot be given as a calculation method of the cross-sectional dimension and the variation ratio. (d) In the past, the optimization scheme only aims at a specific engineering project, a great deal of manpower and time are required for carrying out scheme trial and comparison every time a new project is met, and the optimal design cannot be given in place in one step. (e) The CFD technology has high requirements on professional quality of designers, and the skilled application of the CFD technology needs the capability of proficiency of higher fluid mechanics, higher heat transfer science, computer programming and the like, and cannot meet the requirement of engineering rapid design.
In summary, the variable cross-section uniform air supply pipeline is an advanced concept, but a design method for meeting the rapid requirements of engineering is not yet available.
Disclosure of Invention
The invention provides a design method of a variable cross-section uniform air supply pipeline of a rail transit vehicle, which aims to adapt to various vehicle types, avoid adding a blocking body in the pipeline, reduce the conveying resistance and energy consumption, judge whether the maximum flow velocity in the pipeline, the maximum arrangeable area of an air outlet, the maximum arrangeable cross-section area of the variable cross-section pipeline, the minimum conveying power of an air supply branch and even the air conditioner partition borne by the air supply branch are reasonable or not, provide a calculation method of the cross-section dimension and the variation ratio of the variable cross-section pipeline, realize the static pressure air supply in a full sense and meet the requirement of rapid engineering design.
The invention is realized by the following technical scheme:
a design method of a variable cross-section uniform air supply pipeline of a rail transit vehicle comprises the following steps:
s1, dividing air conditioner partitions, and determining necessary parameters and limiting conditions of air supply pipeline design;
S2, calculating the wind speed v r of a wind pipe with the smallest section of the air supply pipeline, and judging whether v r exceeds the maximum allowable wind speed v rmax;
If v r≤vrmax appears in the step S2, carrying out the next step; if v r＞vrmax, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
S3, the number of pipe sections divided by the variable-section air pipe is assumed to be n, and the air quantity Q i of each section, the length L m of each pipe section, the air quantity Q m and the air quantity Q i-(i+1) are calculated;
S4, calculating the minimum width w omin of the air outlet, and judging whether w omin exceeds the maximum width w ob of the air outlet which can be arranged;
If w omin≤wob appears in the step S4, the next step is carried out; if w omin＞wob, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
s5, calculating the minimum sectional area S 0min of the variable-section air pipe section 0; judging whether S 0min exceeds the maximum cross-sectional area S b of the variable cross-section air pipe which can be arranged;
If S 0min≤Sb occurs in the step S5, the next step is carried out; if S 0min＞Sb, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
S6, calculating the minimum conveying power delta P emin of the air supply branch pipeline, and judging whether delta P emin exceeds the maximum full pressure delta P bmax of the optional power equipment;
If ΔP emin≤ΔPbmax appears in the step S6, the next step is carried out; if the delta P emin＞ΔPbmax indicates that the conveying pressure of the branch is too high, the air conditioner is unreasonable in partition, and the step S1 is returned;
S7, calculating the width w o of the air outlet;
s8, calculating the sectional area S i, the height H i and the width W i of each section of the variable-section air supply pipeline, the variation ratio k H[(i-(i+1)] of the sectional height and the variation ratio k W[(i-(i+1)] of the sectional width of each pipe section and the conveying power delta P e of the air supply branch pipeline.
Preferably, the necessary parameters and constraints of the design of the air supply duct in step S1 include the following: the total air supply quantity Q born by the air supply pipeline, the sectional area S r, the height H r, the width W r and the length L r of the branch minimum section air pipe, the bursting ratio C t of the inlet of the minimum section air pipe, the maximum allowable air speed v rmax of the air supply pipeline, the maximum sectional area S b, the height H b, the width W b and the length L b of the variable section air pipe which can be arranged, the pipe of the air supply pipeline, the type of an air outlet, the maximum area f ob, the width W ob and the length L ob which can be arranged, and the maximum full pressure delta P bmax of the optional power equipment.
Preferably, the method for calculating v r in step S2 includes the following steps:
vr＝Q/Sr
v r -wind speed of the air pipe with the smallest section, m/s;
Q-the total air supply quantity borne by the air supply branch pipeline, m 3/s;
s r, the cross section of the air pipe with the smallest cross section of the air supply branch, and m 2.
Preferably, the method for determining the number of each section and each pipe section in step S3 and the method for calculating the length L m, the air output Q m, the air output Q i-(i+1), and the air output Q i of each section include the following steps:
S31, the number of pipe sections divided by the variable cross section air pipe is assumed to be n, and the cross sections from the head to the tail pipe are 0, 1,2, … … i … …, n-1, n; the pipe sections are 0-1, 1-2 and … … i- (1+1) … …, (n-1) -n;
s32, calculating the length L m of each pipe section of the variable cross-section air pipe;
Lm＝Lb/n
L m, the length of each pipe section of the variable cross-section air pipe, m;
L b, the maximum length of the variable cross-section air pipe which can be arranged, m;
n-the number of pipe sections divided by the variable cross section air pipe is planned;
s33, calculating the air output Q m of each pipe section of the variable cross-section air pipe;
Qm＝Q/n
Q m -the air output of each pipe section of the variable cross-section air pipe, m 3/s;
S34, calculating the air quantity Q i of each section of the variable-section air pipe and the air quantity Q i-(i+1) of each pipe section;
Qi＝Q-Qm×i
Qi-(i+1)＝Q-Qm×i
Q i -the air quantity of each section of the variable-section air pipe, wherein the value range of i is 0 to n, m 3/s;
Q i-(i+1) -the air quantity of each pipe section of the variable cross-section air pipe, m 3/s.
Preferably, the method for calculating the minimum width w omin of the air outlet in step S4 includes the following steps:
s41, determining the maximum allowable flow velocity v omax of an air outlet of the passenger compartment according to the air supply requirement of the passenger compartment;
S42, calculating the minimum area f omin of the air outlet according to the maximum allowable flow velocity v omax of the air outlet;
fomin＝Q/vomax
f omin -the minimum area of the air outlet, m 2;
v omax -maximum allowable flow rate of air outlet, m/s;
S43, calculating the minimum width w omin of the air outlet according to the minimum area f omin of the air outlet and the arrangeable l ob of the air outlet;
womin＝fomin/lob
w omin, the minimum width of the air outlet, m;
l ob -maximum length of the air outlet, m.
Preferably, the method for calculating the minimum cross-sectional area S 0min of the interrupted surface 0 in the step S5 includes the following steps:
s51, drawing out a maximum allowable flow velocity v omax of the tuyere;
s52, drawing out a minimum outflow angle alpha min of the tuyere, and determining an outflow coefficient mu;
s53, calculating the maximum static pressure velocity v jmax of the air outlet according to the maximum allowable flow velocity v omax and the outflow coefficient mu of the air outlet;
vjmax＝vomax/μ
v jmax -maximum static pressure velocity of air outlet, m/s;
mu-flow coefficient of air outlet;
S54, calculating the maximum static pressure P jmax of the air outlet according to the maximum static pressure speed v jmax of the air outlet;
Pjmax＝ρvjmax 2/2
P jmax -the maximum static pressure of the air outlet, pa;
ρ -density of the pipeline transport fluid, kg/m 3, air taken 1.20kg/m 3;
S55, calculating the maximum dynamic pressure velocity v 0dmax of the section 0 according to the maximum static pressure velocity v jmax and the minimum outflow angle alpha min of the air outlet;
v0dmax＝vjmax/tan(αmin)
v 0dmax -maximum dynamic pressure velocity of section 0, m/s;
S56, calculating the minimum sectional area S 0min of the section 0 according to the maximum dynamic pressure speed v 0dmax of the section 0;
S0min＝Q/v0dmax
S 0min -minimum cross-sectional area of section 0, m 2.
Preferably, the method for calculating Δp emin in step S6 includes the following steps:
S601, calculating the flow equivalent diameter D r of the air pipe with the minimum section of the branch according to the height H r and the width W r of the air pipe with the minimum section;
D r —flow velocity equivalent diameter of the smallest section air pipe (flexible connection air pipe), m;
W r, the width of the flexible connection air pipe, m;
H r, the height of the flexible connection air pipe, m;
S602, checking the specific friction R r of the flexible connecting air pipe according to the air quantity Q and the flow equivalent diameter D r of the flexible connecting air pipe;
S603, calculating the on-way resistance delta P ry of the flexible connecting air pipe according to the specific friction R r and the length L r of the flexible connecting air pipe;
ΔPry＝Rr×Lr
ΔP ry -the resistance along the way of the flexible connection duct, pa/m;
r r -the specific friction of the flexible connection air pipe, pa/m;
L r, the length of the flexible connection air pipe, m;
S604, calculating dynamic pressure P rd of the flexible connecting air pipe according to the wind speed v r of the flexible connecting air pipe;
Prd＝ρvr 2/2
p rd, dynamic pressure of flexible connection air pipe, pa;
S605, checking the number of local resistance systems epsilon r of the soft connecting air pipe inlet sudden shrinkage according to the sudden shrinkage ratio C ts of the soft connecting air pipe inlet;
S606, calculating local resistance delta P rj of the flexible connecting air pipe according to the number of the local resistance system epsilon r of the sudden shrinkage of the inlet of the flexible connecting air pipe and the dynamic pressure P rd;
ΔPrj＝εr×Prd
ΔP rj —local resistance of flexible connection air duct, pa;
epsilon r -a local resistance system of the soft connecting air pipe inlet bursting;
S607, calculating total resistance delta P r of the flexible connecting air pipe according to the on-way resistance delta P ry and the local resistance delta P rj of the flexible connecting air pipe;
ΔPr＝ΔPry+ΔPrj
ΔP r -total resistance of flexible connection duct, pa;
S608, calculating the minimum dynamic pressure velocity v 0dmin of the section 0 according to the air quantity Q 0 of the section 0 of the variable-section air pipe and the arrangeable maximum section area S b;
v0dmin＝Q/Sb
v 0dmin -minimum dynamic pressure velocity of section 0, m/s;
S609, calculating the minimum dynamic pressure P 0dmin of the section 0 according to the minimum dynamic pressure speed v 0dmin of the section 0;
P0dmin＝ρv0dmin 2/2
p 0dmin, the minimum dynamic pressure of section 0, pa;
S610, determining an outflow coefficient mu of the air outlet of the pipe section 0-1 according to a minimum outflow angle alpha min of the air outlet of the pipe section 0-1;
s611, calculating a minimum static pressure speed v jmin according to a minimum dynamic pressure speed v 0dmin of the section 0 and a minimum outflow angle alpha min of an air outlet;
vjmin＝v0dmin×tan(αmin)
v jmin -minimum static pressure speed of pipe section 0-1 air outlet, m/s;
S612, calculating the minimum static pressure P jmin of the air outlet according to the minimum static pressure speed v jmin of the air outlet;
Pjmin＝ρvjmin 2/2
P jmin -minimum static pressure of air outlet, pa;
s613, calculating a sudden expansion ratio C tk of a section 0 inlet (soft connection outlet);
Ctk＝A0/A1
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S614, checking the number of the local resistance system epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet (soft connection outlet) of the section 0;
S615, calculating the minimum local resistance delta P 0jmin of the section 0 according to the number of the local resistance system epsilon 0 of the section 0 and the minimum dynamic pressure P 0dmin;
ΔP0jmin＝ε0×P0dmin
Δp 0jmin —minimum local resistance of section 0, pa;
Epsilon 0 -local drag coefficient of section 0;
S616, calculating the minimum full pressure P 0qmin of the section 0 according to the minimum dynamic pressure P 0dmin, the minimum local resistance delta P 0jmin of the section 0 and the minimum static pressure P jmin of the air outlet;
P0qmin＝P0dmin+ΔP0jmin+Pjmin
p 0qmin -minimum full pressure of section 0, pa;
S617, determining the resistance delta P x of other irregular local resistance components;
S618, determining a minimum richness K min of the conveying power of the air supply branch;
s619, calculating the minimum conveying power delta P emin of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the minimum total pressure P 0qmin of the section 0, the resistance delta P x of other irregular local resistance components and the minimum richness K min of the conveying power;
ΔPemin＝(1+Kmin)×(ΔPr+P0qmin+ΔPx)
Δp emin —minimum delivery power of the air supply branch, pa;
K min —minimum enrichment of the air supply branch conveying power;
Δp x —resistance of other irregular local resistance member, pa.
Preferably, the method for calculating the width w o of the air outlet in step S7 includes the following steps:
S71, according to the requirement of a carriage passenger room on the air supply speed, the average outflow speed v o of an air port is worked out;
S72, calculating the total area f o of the air outlet according to the average outflow speed v o of the air outlet;
fo＝Q/vo
f o, the total area of the air outlet, m 2;
v o -the average outflow speed of the tuyere, m/s;
s73, drawing out the length l o of the tuyere;
S74, calculating the width w o of the air outlet according to the total area f o and the planned length l o of the air outlet;
wo＝fo/lo
w o -width of air outlet, m.
Preferably, in the step S8, the calculation method of the cross-sectional area S i, the height H i, the width W i of each cross-section of the variable-section air supply duct, the variation ratio k H[(i-(i+1)] of the cross-section height and the variation ratio k W[(i-(i+1)] of the cross-section width of each pipe section, and the conveying power Δp e of the air supply branch duct includes the following steps:
s801, according to the air supply requirement of a passenger room, the outflow speed v o of an air port is drawn;
S802, calculating the ratio of the relative flow Q m-0 of the air outlet of the pipe section 0-1;
Qm-0＝Qm/Q0-1
Q m-0 -relative flow of pipe section 0-1 air outlet;
Q 0-1 -air quantity of pipe section 0-1, m 3/s;
s803, according to the air supply requirement of the passenger room, an air outlet angle alpha is drawn out;
S804, determining an outflow coefficient mu according to the relative flow Q m-0 and the outflow angle alpha of the air outlet of the pipe section 0-1;
S805, calculating the static pressure velocity v j of the air outlet according to the outflow velocity v o and the outflow coefficient mu of the air outlet;
vj＝vo/μ
v j -static pressure speed of air outlet, m/s;
Mu-the outflow coefficient of the air outlet;
v o -the outflow speed of the tuyere, m/s;
S806, calculating a static pressure P j of the air outlet according to a static pressure speed v j of the air outlet;
Pj＝ρvj 2/2
P j -static pressure of air outlet, pa;
S807, calculating the dynamic pressure velocity v 0d of the section 0 according to the static pressure velocity v j of the air outlet and the planned outflow angle alpha;
v0d＝vj/tanα
v 0d -dynamic pressure velocity of section 0, m/s;
Alpha-the outlet angle alpha of the air outlet is drawn;
S808, calculating the sectional area S 0 of the section 0 according to the dynamic pressure speed v 0d and the flow Q 0 of the section 0, and judging the relative sizes of S 0 and S b;
S0＝Q0/v0d
S 0, the sectional area of section 0, m 2;
If S 0≤Sb in the step S808, the next step is performed; if S 0＞Sb, returning to step S801;
s809, drawing up the height H 0 of the section 0;
S810, calculating the width W 0 of the section 0 according to the height H 0 and the sectional area S 0 of the section 0;
W0＝S0/H0
W 0 -width of section 0, m;
s 0, the area of section 0, m 2;
H 0, the height of the section 0, m;
S811, calculating dynamic pressure P 0d of the section 0 according to dynamic pressure speed v 0d of the section 0;
P0d＝ρv0d 2/2
P 0d, dynamic pressure of section 0, pa;
s812, calculating a sudden expansion ratio C tk of a section 0 inlet (soft connection outlet);
Ctk＝A0/A1
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S813, checking the number of the sudden expansion local resistance system epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet (soft connection outlet) of the section 0;
S814, calculating the sudden expansion local resistance P 0j of the section 0 according to the sudden expansion local resistance system epsilon 0 number of the section 0 and the dynamic pressure P 0d;
P0j＝ε0×P0d
p 0j, the sudden expansion local resistance of the section 0, pa;
epsilon 0 -the sudden expansion local resistance coefficient of section 0;
S815, calculating the total pressure P 0q of the section 0 according to the dynamic pressure P 0d, the static pressure P j and the sudden expansion local resistance P 0j of the section 0;
P0q＝Pj+P0d+P0j
P 0q -full pressure of section 0, pa;
S816, determining the resistance delta P x of other irregular local resistance components;
S817, determining the degree of abundance K of the conveying power of the air supply branch;
S818, calculating the conveying power delta P e of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the total pressure P 0q of the section 0, the resistance delta P x of other irregular local resistance components and the richness K of the conveying power, and judging whether delta P e is reasonable or not;
ΔPe＝(1+K)×(ΔPr+P0q+ΔPx)
Δp e —the power of the air supply branch, pa;
k, the richness of the power delivered by the air supply branch;
Δp x —resistance of other irregular local resistance member, pa;
If ΔP e≤ΔPbmax in step S818, the design is reasonable, and the next step is performed; if ΔP e＞ΔPbmax is not reasonable, returning to step S801;
s819, calculating the flow equivalent diameter D 0 of the section 0 according to the width W 0 and the height H 0 of the section 0;
d 0 —flow equivalent diameter of section 0, m;
W 0 -width of section 0, m;
H 0, the height of the section 0, m;
S820, checking the specific friction R (0-1) of the pipe section 0-1 by taking the flow equivalent diameter D 0 of the section 0 as the approximate value of the pipe section 0-1 according to the air quantity Q 0-1 of the pipe section 0-1;
S821, calculating the on-way resistance delta P (0-1)y of the pipe section 0-1 according to the specific friction R (0-1) and the length L m of the pipe section 0-1;
ΔP(0-1)y＝R(0-1)×Lm
ΔP (0-1)y -the resistance of the pipe section 0-1 in the path, pa;
R (0-1) -the specific friction of the pipe section 0-1, pa/m;
S822, checking a local resistance coefficient epsilon (0-1) of a straight-through part of the pipe section 0-1 according to the relative flow Q m-0 of the air outlet of the pipe section 0-1;
S823, calculating the local resistance delta P (0-1)j of the pipe section 0-1 according to the dynamic pressure P 0d of the section 0 and the local resistance coefficient epsilon (0-1) of the straight-through part of the pipe section 0-1;
ΔP(0-1)j＝ε(0-1)×P0d
ΔP (0-1)j -the local resistance of the pipe section 0-1, pa;
epsilon (0-1) -the local drag coefficient of pipe segment 0-1;
S824, calculating the full pressure P 1q of the section 1 according to the full pressure P 0q of the section 0, the on-way resistance delta P (0-1)y and the local resistance delta P (0-1)j of the pipe section 0-1;
P1q＝P0q-(ΔP(0-1)y+ΔP(0-1)j)
p 1q -full pressure of section 1, pa;
S825, calculating dynamic pressure P 1d of the section 1 according to the full pressure P 1q of the section 1 and the static pressure P j for keeping the air outlet uniformly supplying air, and judging whether P 1d is reasonable or not;
P1d＝P1q-Pj
p 1d, dynamic pressure of section 1, pa;
If P 1d in the step S825 is more than or equal to 0, the design is reasonable, and the next step is carried out; if P 1d is less than 0, the design is unreasonable to return to the step S801;
s826, calculating the dynamic pressure speed v 1d of the section 1 according to the dynamic pressure P 1d of the section 1;
v 1d -dynamic pressure velocity of section 1, m/s;
S827, calculating the sectional area S 1 of the section 1 according to the dynamic pressure speed v 1d and the wind quantity Q 1 of the section 1;
S1＝Q1/v1d
S 1, the sectional area of section 1, m 2;
S828, the height H 1 of the section 1 is calculated;
S829, calculating the width W 1 of the section 1 according to the sectional area S 1 and the planned height H 1 of the section 1;
W1＝S1/H1
H 1, the height of the section 1, m;
W 1 -width of section 1, m;
S830, calculating the change ratio k H(0-1) of the section heights of the pipe sections 0-1 according to the height H 0 of the section 0 and the height H 1 of the section 1;
kH(0-1)＝H1/H0
k H(0-1) -the variation ratio of the section height of the pipe section 0-1;
S831, calculating the change ratio k W(0-1) of the section width of the pipe section 0-1 according to the width W 0 of the section 0 and the width W 1 of the section 1;
kW(0-1)＝W1/W0
k W(0-1) -the ratio of the variation of the section width of the tube section 0-1;
S832, repeating the steps from S819 to S831, and the height H i and the width W i of the subsequent section, the variation ratio k H[i-(i+1)] of the section height of the subsequent section and the variation ratio k W[i-(i+1)] of the section width can be calculated;
If the subsequent tube segment uses the same ratio of variation in section height and the same ratio of variation in section width as the preceding proximal tube segment, then there is,
Hi＝H(i-1)×kH[(i-1)-i]
Wi＝W(i-1)×kW[(i-1)-i]
H i, the height of the section i, m;
H i, the height of the section i, m;
k H[(i-1)-i] -the ratio of the section height changes of the tube sections [ (i-1) -i ];
W i -width of section i, m;
W i -width of section i, m;
k W[(i-1)-i] -the ratio of the cross-sectional width changes of the tube sections [ (i-1) -i ].
The beneficial effects are that: compared with the traditional equal-section pipeline, the pipeline conveying device can adapt to vehicles with various dimensions; compared with the traditional variable-section air supply pipeline, the resistance in the pipeline can be reduced, and the conveying resistance and the energy consumption are reduced; compared with the traditional equal-section and variable-section air supply pipelines, the static pressure uniform air supply in full significance can be realized; compared with the CFD simulation method, the method can meet the requirements of rapid engineering;
In addition, the invention also provides a calculation method for judging whether the maximum flow velocity in the pipeline, the maximum arrangeable area of the air outlet, the maximum arrangeable sectional area of the variable cross-section pipeline, the minimum conveying power of the air supply branch and the air conditioner partition borne by the air supply branch are reasonable or not and the cross-section dimension and the variation ratio of the variable cross-section pipeline, so that blindness and heuristics of the traditional design method are avoided, the material cost and the time cost required by the test can be saved, and an optimization scheme with even air supply and low running energy consumption can be provided;
The invention can be used for not only designing the variable cross-section air supply pipeline of the ventilation air-conditioning system of the planned vehicle, but also evaluating the variable cross-section air supply pipeline of the ventilation air-conditioning system of the finished vehicle. The invention can also be used for the design and evaluation of uniform and non-uniform outflow ducts of other vehicles, other spaces, other equipment, other fluids, other engineering fields, other air outlet types.
Drawings
Fig. 1 is a schematic diagram of a variable cross-section air supply pipeline of a No.1 branch of an air conditioning system of a subway train on the Shanghai according to the design of the invention.
Fig. 2 is a general technical roadmap of the invention.
FIG. 3 is a technical route diagram of step S3 of the present invention.
FIG. 4 is a technical scheme of step S4 of the present invention.
FIG. 5 is a technical route diagram of step S5 of the present invention.
FIG. 6 is a technical scheme of step S6 of the present invention.
FIG. 7 is a technical scheme of step S7 of the present invention.
FIG. 8 is a technical scheme of step S8 of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to the attached drawings: the present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are provided, but the protection scope of the present invention is not limited to the following embodiments.
As shown in fig. 1-8:
Example one, design of variable cross-section air supply pipeline of No. 1 branch of air conditioning system of certain subway train in Shanghai
S1, dividing air conditioner partitions, and determining necessary parameters and limiting conditions of air supply pipeline design;
The total air supply quantity Q=800 m 3/h(0.22m3/s born by a No. 1 branch air supply pipeline of an air conditioning system of a certain subway train in the Shanghai subway); the cross-sectional area S r＝0.03m2 of the air pipe with the smallest section (namely a soft connecting air pipe and an equal cross-section) of the branch, the height H r =0.10 m, the width W r =0.30 m and the length L r =2.00 m, and the shrinkage ratio C ts =0.4 of the air pipe with the smallest section; maximum allowable wind speed v rmax =10m/S, maximum cross-sectional area S b＝0.12m2 in which the variable cross-section ductwork can be arranged, height H b =0.15 m, width W b =0.80 m, and length L b =4.60 m; the pipes of the air supply pipeline are all common galvanized steel plates; the air outlet is strip-shaped, the largest area f ob＝1.38m2, the width w ob =0.30m and the length l ob =4.60 m of which the air outlet can be arranged; maximum full pressure Δp bmax =100 pa of the optional power plant;
S2, calculating the wind speed v r of a wind pipe with the smallest section of the air supply pipeline, and judging whether v r exceeds the maximum allowable wind speed v rmax;
vr＝Q/Sr＝0.22÷0.03＝7.33m/s
v r -wind speed of the air pipe with the smallest section, m/s;
Q-the total air supply quantity borne by the air supply branch pipeline, m 3/s;
S r, the cross section of an air pipe with the smallest cross section of an air supply branch, m 2;
(v r＝7.33m/s)＜(vrmax = 10 m/s) to proceed to the next step;
S3, the number of pipe sections divided by the variable cross section air pipe is assumed to be n, and the air quantity Q i of each cross section, the length L m of each pipe section, the air quantity Q m and the air quantity Q i-(i+1) are calculated;
S31, the number of pipe sections divided by the variable cross section air pipe is assumed to be n=2, the cross section of the tail pipe from the head to the tail pipe is 0, 1 and 2, and the pipe sections are 0-1 and 1-2;
s32, calculating the length L m of each pipe section of the variable cross-section air pipe;
Lm＝Lb/n＝4.6/2＝2.3m
L m, the length of each pipe section of the variable cross-section air pipe, m;
L b, the maximum length of the variable cross-section air pipe which can be arranged, m;
n-the number of pipe sections divided by the variable cross section air pipe is planned;
s33, calculating the air output Q m of each pipe section of the variable cross-section air pipe;
Qm＝Q/n＝0.22/2＝0.11m3/s
Q m -the air output of each pipe section of the variable cross-section air pipe, m 3/s;
S34, calculating the air quantity Q i of each section of the variable-section air pipe and the air quantity Q i-(i+1) of each pipe section;
Q0＝Q＝0.22m3/s
Q1＝Q-Qm×i＝0.22-0.11×1＝0.11m3/s
Q2＝Q-Qm×i＝0.22-0.11×2＝0m3/s
Q0-1＝Q＝0.22m3/s
Q1-2＝Q-Qm×i＝0.22-0.11×1＝0.11m3/s
Q i -the air quantity of each section of the variable-section air pipe, wherein the value range of i is 0 to n, m 3/s;
Q i-(i+1) -the air quantity of each pipe section of the variable cross-section air pipe, m 3/s;
S4, calculating the minimum width w omin of the air outlet, and judging whether w omin exceeds the maximum width w ob of the air outlet which can be arranged;
S41, determining the maximum allowable flow velocity v omax = 2.0m/s of an air outlet of a passenger compartment according to the air supply requirement of the passenger compartment; ;
S42, calculating the minimum area f omin of the air outlet according to the maximum allowable flow velocity v omax of the air outlet;
fomin＝Q/vomax＝0.22/2.0＝0.11m2
f omin -the minimum area of the air outlet, m 2;
v omax -maximum allowable flow rate of air outlet, m/s;
S43, calculating the minimum width w omin of the air outlet according to the minimum area f omin of the air outlet and the arrangeable l ob of the air outlet;
womin＝fomin/lob＝0.11/4.6＝0.02m
w omin, the minimum width of the air outlet, m;
l ob, the maximum length of the air outlet which can be arranged, m;
(w omin0.02m)＜(wob =0.30 m), the next step is performed;
s5, calculating the minimum sectional area S 0min of the variable-section air pipe section 0; judging whether S 0min exceeds the maximum cross-sectional area S b of the variable cross-section air pipe which can be arranged;
S51, drawing out a maximum allowable flow velocity v omax = 2.00m/s;
s52, drawing out a minimum outflow angle alpha min of the tuyere, and determining an outflow coefficient mu;
the minimum outflow angle alpha min =60° of the tuyere is calculated, and the outflow coefficient of the orifice with sharp edges in the figure 4-1-6 of a fluid delivery network (fourth edition) which is mainly compiled by Cha Fuxiang Chitosan, which is beneficial to people, is obtained to obtain mu=0.6;
s53, calculating the maximum static pressure velocity v jmax of the air outlet according to the maximum allowable flow velocity v omax and the outflow coefficient mu of the air outlet;
vjmax＝vomax/μ＝2.00/0.6＝3.33m/s
v jmax -maximum static pressure velocity of air outlet, m/s;
mu-flow coefficient of air outlet;
S54, calculating the maximum static pressure P jmax of the air outlet according to the maximum static pressure speed v jmax of the air outlet;
Pjmax＝ρvjmax 2/2＝1.20×(3.33m/s)2/2＝6.65Pa
P jmax -the maximum static pressure of the air outlet, pa;
ρ -density of the pipeline transport fluid, kg/m 3, air taken 1.20kg/m 3;
S55, calculating the maximum dynamic pressure velocity v 0dmax of the section 0 according to the maximum static pressure velocity v jmax and the minimum outflow angle alpha min of the air outlet;
v0dmax＝vjmax/tan(αmin)＝3.33/1.73＝1.92m/s
v 0dmax -maximum dynamic pressure velocity of section 0, m/s;
S56, calculating the minimum sectional area S 0min of the section 0 according to the maximum dynamic pressure speed v 0dmax of the section 0;
S0min＝Q/v0dmax＝0.22/1.92＝0.11m2
s 0min -minimum cross-sectional area of section 0, m 2;
(S 0min＝0.11m2)＜(Sb＝0.12m2) performing the next step;
S6, calculating the minimum conveying power delta P emin of the air supply branch pipeline, and judging whether delta P emin exceeds the maximum full pressure delta P bmax of the optional power equipment;
S601, calculating the flow equivalent diameter D r of the air pipe with the minimum section of the branch according to the height H r and the width W r of the air pipe with the minimum section;
D r —flow velocity equivalent diameter of the smallest section air pipe (flexible connection air pipe), m;
W r, the width of the flexible connection air pipe, m;
H r, the height of the flexible connection air pipe, m;
S602, checking the specific friction R r of the flexible connecting air pipe according to the air quantity Q and the flow equivalent diameter D r of the flexible connecting air pipe;
According to the friction resistance line calculation diagram of the ventilation pipeline unit length of the figure 3-6-1 in the fluid transmission and distribution pipe network (fourth edition) of the soft connecting air pipe, wherein the air quantity Q=0.22 m 3/s and the flow equivalent diameter D r =0.26 m, and Cha Fuxiang, the friction resistance line calculation diagram of the ventilation pipeline unit length of the figure 3-6-1 in the fluid transmission and distribution pipe network (fourth edition) is known that R r =1.05 Pa/m;
S603, calculating the on-way resistance delta P ry of the flexible connecting air pipe according to the specific friction R r and the length L r of the flexible connecting air pipe;
ΔPry＝Rr×Lr＝1.05Pa/m×2.0m＝2.10Pa
ΔP ry -the resistance along the way of the flexible connection duct, pa/m;
r r -the specific friction of the flexible connection air pipe, pa/m;
L r, the length of the flexible connection air pipe, m;
S604, calculating dynamic pressure P rd of the flexible connecting air pipe according to the wind speed v r of the flexible connecting air pipe;
Prd＝ρvr 2/2＝1.20kg/m3×(7.33m/s)2＝64.47Pa
p rd, dynamic pressure of flexible connection air pipe, pa;
S605, checking the number of local resistance systems epsilon r of the soft connecting air pipe inlet sudden shrinkage according to the sudden shrinkage ratio C ts of the soft connecting air pipe inlet;
When the sudden shrinkage ratio of the inlet of the soft connecting air pipe is C ts =0.4, cha Fuxiang is used for weaving a local resistance coefficient table of a fluid delivery and distribution pipe network (third edition) of the folk owner, so that the local resistance coefficient epsilon r of the sudden shrinkage of the inlet of the soft connecting air pipe is 0.34;
S606, calculating local resistance delta P rj of the flexible connecting air pipe according to the number of the local resistance system epsilon r of the sudden shrinkage of the inlet of the flexible connecting air pipe and the dynamic pressure P rd;
ΔPrj＝εr×Prd＝0.34×64.47Pa＝21.92Pa
ΔP rj —local resistance of flexible connection air duct, pa;
epsilon r -a local resistance system of the soft connecting air pipe inlet bursting;
S607, calculating total resistance delta P r of the flexible connecting air pipe according to the on-way resistance delta P ry and the local resistance delta P rj of the flexible connecting air pipe;
ΔPr＝ΔPry+ΔPrj＝2.10Pa+21.92Pa＝24.02Pa
ΔP r -total resistance of flexible connection duct, pa;
S608, calculating the minimum dynamic pressure velocity v 0dmin of the section 0 according to the air quantity Q 0 of the section 0 of the variable-section air pipe and the arrangeable maximum section area S b;
v0dmin＝Q/Sb＝0.22m3/s÷0.12m2＝1.83m/s
v 0dmin -minimum dynamic pressure velocity of section 0, m/s;
S609, calculating the minimum dynamic pressure P 0dmin of the section 0 according to the minimum dynamic pressure speed v 0dmin of the section 0;
P0dmin＝ρv0dmin 2/2＝1.2kg/m3×(1.83m/s)2÷2＝2.01Pa
p 0dmin, the minimum dynamic pressure of section 0, pa;
S610, determining an outflow coefficient mu of the air outlet of the pipe section 0-1 according to a minimum outflow angle alpha min of the air outlet of the pipe section 0-1;
according to the minimum outflow angle alpha min =60° of the air outlet, the outflow coefficient of the sharp-edged orifice in fig. 4-1-6 of a fluid delivery network (fourth edition) which is mainly compiled by Cha Fuxiang Zhaoxiaomin for people, and the mu=0.6 is obtained;
s611, calculating a minimum static pressure speed v jmin according to a minimum dynamic pressure speed v 0dmin of the section 0 and a minimum outflow angle alpha min of an air outlet;
vjmin＝v0dmin×tan(αmin)＝v0dmin×1.73＝1.83m/s×1.73＝3.17m/s
v jmin -minimum static pressure speed of pipe section 0-1 air outlet, m/s;
S612, calculating the minimum static pressure P jmin of the air outlet according to the minimum static pressure speed v jmin of the air outlet;
Pjmin＝ρvjmin 2/2＝1.2kg/m3×(3.17m/s)2÷2＝6.02Pa
P jmin -minimum static pressure of air outlet, pa;
s613, calculating a sudden expansion ratio C tk of a section 0 inlet (soft connection outlet);
Ctk＝A0/A1＝0.03m2/0.12m2＝0.25
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S614, checking the number of the local resistance system epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet (soft connection outlet) of the section 0;
When the sudden expansion ratio of the inlet with the section 0 is C tk =0.25, the local resistance coefficient table of the Cha Fuxiang cross-country code fluid transmission and distribution network (third edition) annex of the Chinese zodiac beneficial people is adopted, and the local resistance coefficient epsilon 0 is 0.57;
S615, calculating the minimum local resistance delta P 0jmin of the section 0 according to the number of the local resistance system epsilon 0 of the section 0 and the minimum dynamic pressure P 0dmin;
ΔP0jmin＝ε0×P0dmin＝0.57×2.01Pa＝1.15Pa
Δp 0jmin —minimum local resistance of section 0, pa;
Epsilon 0 -local drag coefficient of section 0;
S616, calculating the minimum full pressure P 0qmin of the section 0 according to the minimum dynamic pressure P 0dmin, the minimum local resistance delta P 0jmin of the section 0 and the minimum static pressure P jmin of the air outlet;
P0qmin＝P0dmin+ΔP0jmin+Pjmin＝2.01Pa+1.15Pa+6.02Pa＝9.18Pa
p 0qmin -minimum full pressure of section 0, pa;
S617, determining the resistance delta P x of other irregular local resistance components;
No other resistance of the branch, Δp x =0pa;
S618, determining a minimum richness K min of the conveying power of the air supply branch;
Taking K min = 10%;
s619, calculating the minimum conveying power delta P emin of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the minimum total pressure P 0qmin of the section 0, the resistance delta P x of other irregular local resistance components and the minimum richness K min of the conveying power;
ΔPemin＝(1+Kmin)×(ΔPr+P0qmin+ΔPx)＝(1+10％)×(24.02Pa+9.18Pa+0Pa)＝36.52Pa
Δp emin —minimum delivery power of the air supply branch, pa;
K min —minimum enrichment of the air supply branch conveying power;
Δp x —resistance of other irregular local resistance member, pa;
(Δp emin＝36.52Pa)＜(ΔPbmax =100 Pa) for the next step;
S7, calculating the width w o of the air outlet;
s71, according to the requirement of a carriage passenger room on the air supply speed, the average outflow speed v o = 1.00m/s of an air port is calculated;
S72, calculating the total area f o of the air outlet according to the average outflow speed v o of the air outlet;
fo＝Q/vo＝0.22m3/s÷1.00m/s＝0.22m2
f o, the total area of the air outlet, m 2;
v o -the average outflow speed of the tuyere, m/s;
s73, drawing out the length l o of the tuyere;
the maximum arrangeable length of the air outlet is the length of the air outlet, and l o＝lob = 4.6m;
S74, calculating the width w o of the air outlet according to the total area f o and the planned length l o of the air outlet;
wo＝fo/lo＝0.22m2÷4.6＝0.05m
w o, the width of the air outlet, m;
S8, calculating the sectional area S i, the height H i and the width W i of each section of the variable-section air supply pipeline, the variation ratio k H[(i-(i+1)] of the sectional height and the variation ratio k W[(i-(i+1)] of the sectional width of each pipe section and the conveying power delta P e of the air supply branch pipeline;
s801, according to the air supply requirement of a passenger room, the outflow speed v o of an air port is drawn;
According to the passenger room air supply requirement, v o = 1.92m/s is formulated;
S802, calculating the ratio of the relative flow Q m-0 of the air outlet of the pipe section 0-1;
Qm-0＝Qm/Q0-1＝0.11m3/s÷0.22m3/s＝0.5；
Q m-0 -relative flow of pipe section 0-1 air outlet;
Q 0-1 -air quantity of pipe section 0-1, m 3/s;
s803, according to the air supply requirement of the passenger room, an air outlet angle alpha is drawn out;
according to the passenger room air supply requirement, alpha=60 degrees is formulated;
S804, determining an outflow coefficient mu according to the relative flow Q m-0 and the outflow angle alpha of the air outlet of the pipe section 0-1;
according to the outflow coefficient of the orifice with sharp edges of figures 2-3-9 in fluid delivery network (third edition) of the national institute of Mitsui, cha Fuxiang, with Q m-0 =0.5 and outflow angle α=60°, μ=0.6;
S805, calculating the static pressure velocity v j of the air outlet according to the outflow velocity v o and the outflow coefficient mu of the air outlet;
vj＝vo/μ＝1.92m/s÷0.6＝3.20m/s
v j -static pressure speed of air outlet, m/s;
Mu-the outflow coefficient of the air outlet;
v o -the outflow speed of the tuyere, m/s;
S806, calculating a static pressure P j of the air outlet according to a static pressure speed v j of the air outlet;
Pj＝ρvj 2/2＝1.2kg/m3×(3.20m/s)2÷2＝6.14Pa
P j -static pressure of air outlet, pa;
S807, calculating the dynamic pressure velocity v 0d of the section 0 according to the static pressure velocity v j of the air outlet and the planned outflow angle alpha;
v0d＝vj/tanα＝3.20m/s÷tan60＝1.85m/s
v 0d -dynamic pressure velocity of section 0, m/s;
Alpha-the outlet angle alpha of the air outlet is drawn;
S808, calculating the sectional area S 0 of the section 0 according to the dynamic pressure speed v 0d and the flow Q 0 of the section 0, and judging the relative sizes of S 0 and S b;
S0＝Q0/v0d＝0.22m3/s÷1.85m/s＝0.12m2
S 0, the sectional area of section 0, m 2;
(S 0＝0.12m2)＝(Sb＝0.12m2) performing the next step;
s809, drawing up the height H 0 of the section 0;
Let H 0 = 0.15m;
S810, calculating the width W 0 of the section 0 according to the height H 0 and the sectional area S 0 of the section 0;
W0＝S0/H0＝0.12m2÷0.15m＝0.80m
W 0 -width of section 0, m;
s 0, the area of section 0, m 2;
H 0, the height of the section 0, m;
S811, calculating dynamic pressure P 0d of the section 0 according to dynamic pressure speed v 0d of the section 0;
P0d＝ρv0d 2/2＝1.2kg/m3×(1.85m/s)2÷2＝2.05Pa
P 0d, dynamic pressure of section 0, pa;
s812, calculating a sudden expansion ratio C tk of a section 0 inlet (soft connection outlet);
Ctk＝A0/A1＝0.03m2/0.12m2＝0.25
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S813, checking the number of the sudden expansion local resistance system epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet (soft connection outlet) of the section 0;
When the sudden expansion ratio of the inlet with the section 0 is C tk =0.25, the local resistance coefficient table of the Cha Fuxiang cross-country code fluid transmission and distribution network (third edition) annex of the Chinese zodiac beneficial people is adopted, and the local resistance coefficient epsilon 0 is 0.57;
S814, calculating the sudden expansion local resistance P 0j of the section 0 according to the sudden expansion local resistance system epsilon 0 number of the section 0 and the dynamic pressure P 0d;
P0j＝ε0×P0d＝0.57×2.05Pa＝1.17Pa
p 0j, the sudden expansion local resistance of the section 0, pa;
epsilon 0 -the sudden expansion local resistance coefficient of section 0;
S815, calculating the total pressure P 0q of the section 0 according to the dynamic pressure P 0d, the static pressure P j and the sudden expansion local resistance P 0j of the section 0;
P0q＝Pj+P0d+P0j＝6.14Pa+2.05Pa+1.17Pa＝9.36Pa
P 0q -full pressure of section 0, pa;
S816, determining the resistance delta P x of other irregular local resistance components;
No other resistance of the branch, Δp x =0pa;
S817, determining the degree of abundance K of the conveying power of the air supply branch;
taking k=15%;
S818, calculating the conveying power delta P e of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the total pressure P 0q of the section 0, the resistance delta P x of other irregular local resistance components and the richness K of the conveying power, and judging whether delta P e is reasonable or not;
ΔPe＝(1+K)×(ΔPr+P0q+ΔPx)＝(1+15％)×(24.02Pa+9.36Pa+0Pa)＝38.39
Δp e —the power of the air supply branch, pa;
k, the richness of the power delivered by the air supply branch;
Δp x —resistance of other irregular local resistance member, pa;
(Δp e＝38.39Pa)＜(ΔPbmax =100 Pa) and proceeding to the next step;
s819, calculating the flow equivalent diameter D 0 of the section 0 according to the width W 0 and the height H 0 of the section 0;
d 0 —flow equivalent diameter of section 0, m;
W 0 -width of section 0, m;
H 0, the height of the section 0, m;
S820, checking the specific friction R (0-1) of the pipe section 0-1 by taking the flow equivalent diameter D 0 of the section 0 as the approximate value of the pipe section 0-1 according to the air quantity Q 0-1 of the pipe section 0-1;
According to the air quantity Q 0-1＝0.22m3/s of the pipe section 0-1 and the flow equivalent diameter D 0 =0.36 m of the section 0, cha Fuxiang, which is the friction resistance line calculation chart of the ventilation pipeline unit length of the ventilation pipeline of the figure 3-6-1 in the fluid transmission and distribution pipe network (fourth edition) of the Shaoyi Ministry, R (0-1) =0.18 Pa/m is known;
S821, calculating the on-way resistance delta P (0-1)y of the pipe section 0-1 according to the specific friction R (0-1) and the length L m of the pipe section 0-1;
ΔP(0-1)y＝R(0-1)×Lm＝0.18Pa/m×2.30m＝0.41Pa
ΔP (0-1)y -the resistance of the pipe section 0-1 in the path, pa;
R (0-1) -the specific friction of the pipe section 0-1, pa/m;
S822, checking a local resistance coefficient epsilon (0-1) of a straight-through part of the pipe section 0-1 according to the relative flow Q m-0 of the air outlet of the pipe section 0-1;
According to the relative flow rate Q m-0 =0.50 of the air outlet of the pipe section 0-1, cha Fuxiang is used for weaving the local resistance coefficient of the straight-through part of the side hole of the fluid delivery pipe network (third edition) in the table 2-3-6, so as to obtain the local resistance system epsilon (0-1) =0.07 of the straight-through part of the pipe section 0-1;
S823, calculating the local resistance delta P (0-1)j of the pipe section 0-1 according to the dynamic pressure P 0d of the section 0 and the local resistance coefficient epsilon (0-1) of the straight-through part of the pipe section 0-1;
ΔP(0-1)j＝ε(0-1)×P0d＝0.07×2.05Pa＝0.14Pa
ΔP (0-1)j -the local resistance of the pipe section 0-1, pa;
epsilon (0-1) -the local drag coefficient of pipe segment 0-1;
S824, calculating the full pressure P 1q of the section 1 according to the full pressure P 0q of the section 0, the on-way resistance delta P (0-1)y and the local resistance delta P (0-1)j of the pipe section 0-1;
P1q＝P0q-(ΔP(0-1)y+ΔP(0-1)j)＝9.36Pa-(0.41Pa+0.14Pa)＝8.81Pa
p 1q -full pressure of section 1, pa;
S825, calculating dynamic pressure P 1d of the section 1 according to the full pressure P 1q of the section 1 and the static pressure P j for keeping the air outlet uniformly supplying air, and judging whether P 1d is reasonable or not;
P1d＝P1q-Pj＝8.81Pa-6.14Pa＝2.67Pa
p 1d, dynamic pressure of section 1, pa;
(P 1d =2.67 Pa) > 0, reasonable design, and performing the next step;
s826, calculating the dynamic pressure speed v 1d of the section 1 according to the dynamic pressure P 1d of the section 1;
v 1d -dynamic pressure velocity of section 1, m/s;
S827, calculating the sectional area S 1 of the section 1 according to the dynamic pressure speed v 1d and the wind quantity Q 1 of the section 1;
S1＝Q1/v1d＝0.11m3/s÷2.11m/s＝0.052m2
S 1, the sectional area of section 1, m 2;
S828, the height H 1 of the section 1 is calculated;
The height H 1 of the section 1 is assumed to be 0.10m;
S829, calculating the width W 1 of the section 1 according to the sectional area S 1 and the planned height H 1 of the section 1;
W1＝S1/H1＝0.052m2÷0.10m＝0.52m
H 1, the height of the section 1, m;
W 1 -width of section 1, m;
S830, calculating the change ratio k H(0-1) of the section heights of the pipe sections 0-1 according to the height H 0 of the section 0 and the height H 1 of the section 1;
kH(0-1)＝H1/H0＝0.10m÷0.15m＝0.67
k H(0-1) -the variation ratio of the section height of the pipe section 0-1;
S831, calculating the change ratio k W(0-1) of the section width of the pipe section 0-1 according to the width W 0 of the section 0 and the width W 1 of the section 1;
kW(0-1)＝W1/W0＝0.52m÷0.80m＝0.65
k W(0-1) -the ratio of the variation of the section width of the tube section 0-1;
S832, repeating the steps from S819 to S831, and the height H i and the width W i of the subsequent section, the variation ratio k H[i-(i+1)] of the section height of the subsequent section and the variation ratio k W[i-(i+1)] of the section width can be calculated;
The same ratio of section height variation and section width variation is used for the tube 1-2 and the tube 0-1, and as such,
H2＝H1×kH(0-1)＝0.1×0.67＝0.07m
W2＝W1×kW(0-1)＝0.52×0.65＝0.34m
Example two, the total air supply quantity Q=1200m 3/h(0.33m3/s born by the air supply pipeline, and other conditions are the same as those of example one
When the process goes to S2, v r＝Q/Sr＝0.33÷0.03＝11m/s,(vr＝7.33m/s)＞(vrmax = 10m/S appears, the air area of the air conditioner is unreasonable, the branch bears the excessively large air supply quantity, the process needs to return to the step S1, and the air conditioner partition is carried out again;
Example three, the maximum cross-sectional area S b＝0.08m2, the height H b =0.10m, the other conditions and design process are the same as example one
When the process goes to the step S56, the occurrence of the phenomenon (S 0min＝0.11m2)＞(Sb＝0.08m2) occurs, the air area of the air conditioner is unreasonable, the branch bears the excessively large air supply quantity, and the process needs to return to the step S1 to carry out air conditioning partition again;
The design method of the variable cross-section uniform air supply pipeline of the rail transit vehicle can be also applied to the design of other vehicles, other spaces, equipment and other fluids; the device can also be applied to the design of a uniform section air supply pipeline, a non-strip air outlet and a non-uniform air supply pipeline; the method can also be applied to the design of exhaust pipelines; or to the evaluation of designed variable cross-section supply ducts.
The invention is not only used in the field of vehicle engineering, but also suitable for the engineering fields of construction, chemical industry, environment, medicine, mine, electronics, livestock and the like which need uniform fluid delivery and distribution, and has the same application principle and design method.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (4)
1. The design method of the variable cross-section uniform air supply pipeline of the rail transit vehicle is characterized by comprising the following steps of:
s1, dividing air conditioner partitions, and determining necessary parameters and limiting conditions of air supply pipeline design;
S2, calculating the wind speed v r of a wind pipe with the smallest section of the air supply pipeline, and judging whether v r exceeds the maximum allowable wind speed v rmax;
If v r≤vrmax appears in the step S2, carrying out the next step; if v r＞vrmax, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
S3, the number of pipe sections divided by the variable-section air pipe is assumed to be n, and the air quantity Q i of each section, the length L m of each pipe section, the air quantity Q m and the air quantity Q i-(i+1) are calculated;
S4, calculating the minimum width w omin of the air outlet, and judging whether w omin exceeds the maximum width w ob of the air outlet which can be arranged;
If w omin≤wob appears in the step S4, the next step is carried out; if w omin＞wob, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
s5, calculating the minimum sectional area S 0min of the variable-section air pipe section 0; judging whether S 0min exceeds the maximum cross-sectional area S b of the variable cross-section air pipe which can be arranged;
If S 0min≤Sb occurs in the step S5, the next step is carried out; if S 0min＞Sb, the air supply amount born by the branch is too large, the air conditioner partition is unreasonable, and the step S1 is returned;
S6, calculating the minimum conveying power delta P emin of the air supply branch pipeline, and judging whether delta P emin exceeds the maximum full pressure delta P bmax of the optional power equipment;
If ΔP emin≤ΔPbmax appears in the step S6, the next step is carried out; if the delta P emin＞ΔPbmax indicates that the conveying pressure of the branch is too high, the air conditioner is unreasonable in partition, and the step S1 is returned;
S7, calculating the width w o of the air outlet;
S8, calculating the sectional area S i, the height H i and the width W i of each section of the variable-section air supply pipeline, the variation ratio k H[(i-(i+1)] of the sectional height and the variation ratio k W[(i-(i+1)] of the sectional width of each pipe section and the conveying power delta P e of the air supply branch pipeline;
the method for calculating the minimum width w omin of the air outlet in the step S4 comprises the following steps:
s41, determining the maximum allowable flow velocity v omax of an air outlet of the passenger compartment according to the air supply requirement of the passenger compartment;
S42, calculating the minimum area f omin of the air outlet according to the maximum allowable flow velocity v omax of the air outlet;
fomin＝Q/vomax
f omin -the minimum area of the air outlet, m 2;
v omax -maximum allowable flow rate of air outlet, m/s;
S43, calculating the minimum width w omin of the air outlet according to the minimum area f omin of the air outlet and the arrangeable l ob of the air outlet;
womin＝fomin/lob
w omin, the minimum width of the air outlet, m;
l ob, the maximum length of the air outlet which can be arranged, m;
the method for calculating the minimum sectional area S 0min of the interrupt surface 0 in the step S5 comprises the following steps:
s51, drawing out a maximum allowable flow velocity v omax of the tuyere;
s52, drawing out a minimum outflow angle alpha min of the tuyere, and determining an outflow coefficient mu;
s53, calculating the maximum static pressure velocity v jmax of the air outlet according to the maximum allowable flow velocity v omax and the outflow coefficient mu of the air outlet;
vjmax＝vomax/μ
v jmax -maximum static pressure velocity of air outlet, m/s;
mu-flow coefficient of air outlet;
S54, calculating the maximum static pressure P jmax of the air outlet according to the maximum static pressure speed v jmax of the air outlet;
Pjmax＝ρvjmax 2/2
P jmax -the maximum static pressure of the air outlet, pa;
ρ -density of the pipeline transport fluid, kg/m 3, air taken 1.20kg/m 3;
S55, calculating the maximum dynamic pressure velocity v 0dmax of the section 0 according to the maximum static pressure velocity v jmax and the minimum outflow angle alpha min of the air outlet;
v0dmax＝vjmax/tan(αmin)
v 0dmax -maximum dynamic pressure velocity of section 0, m/s;
S56, calculating the minimum sectional area S 0min of the section 0 according to the maximum dynamic pressure speed v 0dmax of the section 0;
S0min＝Q/v0dmax
s 0min -minimum cross-sectional area of section 0, m 2;
The method for calculating Δp emin in step S6 includes the following steps:
S601, calculating the flow equivalent diameter D r of the air pipe with the minimum section of the branch according to the height H r and the width W r of the air pipe with the minimum section;
d r —flow velocity equivalent diameter of minimum section air pipe, m;
W r, the width of the flexible connection air pipe, m;
H r, the height of the flexible connection air pipe, m;
S602, checking the specific friction R r of the flexible connecting air pipe according to the air quantity Q and the flow equivalent diameter D r of the flexible connecting air pipe;
S603, calculating the on-way resistance delta P ry of the flexible connecting air pipe according to the specific friction R r and the length L r of the flexible connecting air pipe;
ΔPry＝Rr×Lr
ΔP ry -the resistance along the way of the flexible connection duct, pa/m;
r r -the specific friction of the flexible connection air pipe, pa/m;
L r, the length of the flexible connection air pipe, m;
S604, calculating dynamic pressure P rd of the flexible connecting air pipe according to the wind speed v r of the flexible connecting air pipe;
Prd＝ρvr 2/2
p rd, dynamic pressure of flexible connection air pipe, pa;
S605, checking the number of local resistance systems epsilon r of the soft connecting air pipe inlet sudden shrinkage according to the sudden shrinkage ratio C ts of the soft connecting air pipe inlet;
S606, calculating local resistance delta P rj of the flexible connecting air pipe according to the number of the local resistance system epsilon r of the sudden shrinkage of the inlet of the flexible connecting air pipe and the dynamic pressure P rd;
ΔPrj＝εr×Prd
ΔP rj —local resistance of flexible connection air duct, pa;
epsilon r -a local resistance system of the soft connecting air pipe inlet bursting;
S607, calculating total resistance delta P r of the flexible connecting air pipe according to the on-way resistance delta P ry and the local resistance delta P rj of the flexible connecting air pipe;
ΔPr＝ΔPry+ΔPrj
ΔP r -total resistance of flexible connection duct, pa;
S608, calculating the minimum dynamic pressure velocity v 0dmin of the section 0 according to the air quantity Q 0 of the section 0 of the variable-section air pipe and the arrangeable maximum section area S b;
v0dmin＝Q/Sb
v 0dmin -minimum dynamic pressure velocity of section 0, m/s;
S609, calculating the minimum dynamic pressure P 0dmin of the section 0 according to the minimum dynamic pressure speed v 0dmin of the section 0;
P0dmin＝ρv0dmin 2/2
p 0dmin, the minimum dynamic pressure of section 0, pa;
S610, determining an outflow coefficient mu of the air outlet of the pipe section 0-1 according to a minimum outflow angle alpha min of the air outlet of the pipe section 0-1;
s611, calculating a minimum static pressure speed v jmin according to a minimum dynamic pressure speed v 0dmin of the section 0 and a minimum outflow angle alpha min of an air outlet;
vjmin＝v0dmin×tan(αmin)
v jmin -minimum static pressure speed of pipe section 0-1 air outlet, m/s;
S612, calculating the minimum static pressure P jmin of the air outlet according to the minimum static pressure speed v jmin of the air outlet;
Pjmin＝ρvjmin 2/2
P jmin -minimum static pressure of air outlet, pa;
S613, calculating a sudden expansion ratio C tk of an inlet of the section 0;
Ctk＝A0/A1
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S614, checking the number of the local resistance system epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet of the section 0;
S615, calculating the minimum local resistance delta P 0jmin of the section 0 according to the number of the local resistance system epsilon 0 of the section 0 and the minimum dynamic pressure P 0dmin;
ΔP0jmin＝ε0×P0dmin
Δp 0jmin —minimum local resistance of section 0, pa;
Epsilon 0 -local drag coefficient of section 0;
S616, calculating the minimum full pressure P 0qmin of the section 0 according to the minimum dynamic pressure P 0dmin, the minimum local resistance delta P 0jmin of the section 0 and the minimum static pressure P jmin of the air outlet;
P0qmin＝P0dmin+ΔP0jmin+Pjmin
p 0qmin -minimum full pressure of section 0, pa;
S617, determining the resistance delta P x of other irregular local resistance components;
S618, determining a minimum richness K min of the conveying power of the air supply branch;
s619, calculating the minimum conveying power delta P emin of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the minimum total pressure P 0qmin of the section 0, the resistance delta P x of other irregular local resistance components and the minimum richness K min of the conveying power;
ΔPemin＝(1+Kmin)×(ΔPr+P0qmin+ΔPx)
Δp emin —minimum delivery power of the air supply branch, pa;
K min —minimum enrichment of the air supply branch conveying power;
Δp x —resistance of other irregular local resistance member, pa;
The method for calculating the width w o of the air outlet in the step S7 comprises the following steps:
S71, according to the requirement of a carriage passenger room on the air supply speed, the average outflow speed v o of an air port is worked out;
S72, calculating the total area f o of the air outlet according to the average outflow speed v o of the air outlet;
fo＝Q/vo
f o, the total area of the air outlet, m 2;
v o -the average outflow speed of the tuyere, m/s;
s73, drawing out the length l o of the tuyere;
S74, calculating the width w o of the air outlet according to the total area f o and the planned length l o of the air outlet;
wo＝fo/lo
w o, the width of the air outlet, m;
In the step S8, the calculation method of the cross-sectional area S i, the height H i, the width W i of each section of the variable cross-section air supply pipeline, the variation ratio k H[(i-(i+1)] of the cross-sectional height and the variation ratio k W[(i-(i+1)] of the cross-sectional width of each pipe section, and the conveying power Δp e of the air supply branch pipeline includes the following steps:
s801, according to the air supply requirement of a passenger room, the outflow speed v o of an air port is drawn;
S802, calculating the ratio of the relative flow Q m-0 of the air outlet of the pipe section 0-1;
Qm-0＝Qm/Q0-1
Q m-0 -relative flow of pipe section 0-1 air outlet;
Q 0-1 -air quantity of pipe section 0-1, m 3/s;
s803, according to the air supply requirement of the passenger room, an air outlet angle alpha is drawn out;
S804, determining an outflow coefficient mu according to the relative flow Q m-0 and the outflow angle alpha of the air outlet of the pipe section 0-1;
S805, calculating the static pressure velocity v j of the air outlet according to the outflow velocity v o and the outflow coefficient mu of the air outlet;
vj＝vo/μ
v j -static pressure speed of air outlet, m/s;
Mu-the outflow coefficient of the air outlet;
v o -the outflow speed of the tuyere, m/s;
S806, calculating a static pressure P j of the air outlet according to a static pressure speed v j of the air outlet;
Pj＝ρvj 2/2
P j -static pressure of air outlet, pa;
S807, calculating the dynamic pressure velocity v 0d of the section 0 according to the static pressure velocity v j of the air outlet and the planned outflow angle alpha;
v0d＝vj/tanα
v 0d -dynamic pressure velocity of section 0, m/s;
Alpha-the outlet angle alpha of the air outlet is drawn;
S808, calculating the sectional area S 0 of the section 0 according to the dynamic pressure speed v 0d and the flow Q 0 of the section 0, and judging the relative sizes of S 0 and S b;
S0＝Q0/v0d
S 0, the sectional area of section 0, m 2;
If S 0≤Sb in the step S808, the next step is performed; if S 0＞Sb, returning to step S801;
s809, drawing up the height H 0 of the section 0;
S810, calculating the width W 0 of the section 0 according to the height H 0 and the sectional area S 0 of the section 0;
W0＝S0/H0
W 0 -width of section 0, m;
s 0, the area of section 0, m 2;
H 0, the height of the section 0, m;
S811, calculating dynamic pressure P 0d of the section 0 according to dynamic pressure speed v 0d of the section 0;
P0d＝ρv0d 2/2
P 0d, dynamic pressure of section 0, pa;
S812, calculating the sudden expansion ratio C tk of the inlet of the section 0;
Ctk＝A0/A1
A 0 -the cross-sectional area of a small section pipeline at the sudden expansion or contraction, m 2;
A 1 -the sectional area of a large section pipeline at the sudden expansion or contraction position, m 2;
S813, checking the number of the sudden expansion local resistance systems epsilon 0 of the section 0 according to the sudden expansion ratio C tk of the inlet of the section 0;
S814, calculating the sudden expansion local resistance P 0j of the section 0 according to the sudden expansion local resistance system epsilon 0 number of the section 0 and the dynamic pressure P 0d;
P0j＝ε0×P0d
p 0j, the sudden expansion local resistance of the section 0, pa;
epsilon 0 -the sudden expansion local resistance coefficient of section 0;
S815, calculating the total pressure P 0q of the section 0 according to the dynamic pressure P 0d, the static pressure P j and the sudden expansion local resistance P 0j of the section 0;
P0q＝Pj+P0d+P0j
P 0q -full pressure of section 0, pa;
S816, determining the resistance delta P x of other irregular local resistance components;
S817, determining the degree of abundance K of the conveying power of the air supply branch;
S818, calculating the conveying power delta P e of the air supply branch according to the total resistance delta P r of the flexible connecting air pipe, the total pressure P 0q of the section 0, the resistance delta P x of other irregular local resistance components and the richness K of the conveying power, and judging whether delta P e is reasonable or not;
ΔPe＝(1+K)×(ΔPr+P0q+ΔPx)
Δp e —the power of the air supply branch, pa;
k, the richness of the power delivered by the air supply branch;
Δp x —resistance of other irregular local resistance member, pa;
If ΔP e≤ΔPbmax in step S818, the design is reasonable, and the next step is performed; if ΔP e＞ΔPbmax is not reasonable, returning to step S801;
s819, calculating the flow equivalent diameter D 0 of the section 0 according to the width W 0 and the height H 0 of the section 0;
d 0 —flow equivalent diameter of section 0, m;
W 0 -width of section 0, m;
H 0, the height of the section 0, m;
S820, checking the specific friction R (0-1) of the pipe section 0-1 by taking the flow equivalent diameter D 0 of the section 0 as the approximate value of the pipe section 0-1 according to the air quantity Q 0-1 of the pipe section 0-1;
S821, calculating the on-way resistance delta P (0-1)y of the pipe section 0-1 according to the specific friction R (0-1) and the length L m of the pipe section 0-1;
ΔP(0-1)y＝R(0-1)×Lm
ΔP (0-1)y -the resistance of the pipe section 0-1 in the path, pa;
R (0-1) -the specific friction of the pipe section 0-1, pa/m;
S822, checking a local resistance coefficient epsilon (0-1) of a straight-through part of the pipe section 0-1 according to the relative flow Q m-0 of the air outlet of the pipe section 0-1;
S823, calculating the local resistance delta P (0-1)j of the pipe section 0-1 according to the dynamic pressure P 0d of the section 0 and the local resistance coefficient epsilon (0-1) of the straight-through part of the pipe section 0-1;
ΔP(0-1)j＝ε(0-1)×P0d
ΔP (0-1)j -the local resistance of the pipe section 0-1, pa;
epsilon (0-1) -the local drag coefficient of pipe segment 0-1;
S824, calculating the full pressure P 1q of the section 1 according to the full pressure P 0q of the section 0, the on-way resistance delta P (0-1)y and the local resistance delta P (0-1)j of the pipe section 0-1;
P1q＝P0q-(ΔP(0-1)y+ΔP(0-1)j)
p 1q -full pressure of section 1, pa;
S825, calculating dynamic pressure P 1d of the section 1 according to the full pressure P 1q of the section 1 and the static pressure P j for keeping the air outlet uniformly supplying air, and judging whether P 1d is reasonable or not;
P1d＝P1q-Pj
p 1d, dynamic pressure of section 1, pa;
If P 1d in the step S825 is more than or equal to 0, the design is reasonable, and the next step is carried out; if P 1d is less than 0, the design is unreasonable to return to the step S801;
s826, calculating the dynamic pressure speed v 1d of the section 1 according to the dynamic pressure P 1d of the section 1;
v 1d -dynamic pressure velocity of section 1, m/s;
S827, calculating the sectional area S 1 of the section 1 according to the dynamic pressure speed v 1d and the wind quantity Q 1 of the section 1;
S1＝Q1/v1d
S 1, the sectional area of section 1, m 2;
S828, the height H 1 of the section 1 is calculated;
S829, calculating the width W 1 of the section 1 according to the sectional area S 1 and the planned height H 1 of the section 1;
W1＝S1/H1
H 1, the height of the section 1, m;
W 1 -width of section 1, m;
S830, calculating the change ratio k H(0-1) of the section heights of the pipe sections 0-1 according to the height H 0 of the section 0 and the height H 1 of the section 1;
kH(0-1)＝H1/H0
k H(0-1) -the variation ratio of the section height of the pipe section 0-1;
S831, calculating the change ratio k W(0-1) of the section width of the pipe section 0-1 according to the width W 0 of the section 0 and the width W 1 of the section 1;
kW(0-1)＝W1/W0
k W(0-1) -the ratio of the variation of the section width of the tube section 0-1;
S832, repeating the steps from S819 to S831, and the height H i and the width W i of the subsequent section, the variation ratio k H[i-(i+1)] of the section height of the subsequent section and the variation ratio k W[i-(i+1)] of the section width can be calculated;
If the subsequent tube segment uses the same ratio of variation in section height and the same ratio of variation in section width as the preceding proximal tube segment, then there is,
Hi＝H(i-1)×kH[(i-1)-i]
Wi＝W(i-1)×kW[(i-1)-i]
H i, the height of the section i, m;
H i, the height of the section i, m;
k H[(i-1)-i] -the ratio of the section height changes of the tube sections [ (i-1) -i ];
W i -width of section i, m;
W i -width of section i, m;
k W[(i-1)-i] -the ratio of the cross-sectional width changes of the tube sections [ (i-1) -i ].
2. The method for designing the variable cross-section uniform air supply pipeline of the rail transit vehicle according to claim 1, wherein the step S1 comprises the following steps: the total air supply quantity Q born by an air supply pipeline, the sectional area S r, the height H r, the width W r and the length L r of an air pipe with the smallest section are determined, the shrinkage ratio C t of an inlet of the air pipe with the smallest section, the maximum allowable air speed v rmax of the air supply pipeline, the maximum sectional area S b, the height H b, the width W b and the length L b of the variable-section air pipe, the pipe material of the air supply pipeline, the type of an air outlet, the maximum area f ob, the width W ob and the length L ob of the variable-section air pipe which can be arranged, and the maximum full pressure delta P bmax of optional power equipment.
3. The method for designing the variable cross-section uniform air supply pipeline of the rail transit vehicle according to claim 1, wherein the method for calculating v r in the step S2 comprises the following steps:
vr＝Q/Sr
v r -wind speed of the air pipe with the smallest section, m/s;
Q-the total air supply quantity borne by the air supply branch pipeline, m 3/s;
s r, the cross section of the air pipe with the smallest cross section of the air supply branch, and m 2.
4. The method for designing the variable cross-section uniform air supply pipeline of the rail transit vehicle according to claim 1, wherein the method for determining the number of each cross section and each pipe section in the step S3 and the method for calculating the length L m, the air output Q m, the air output Q i-(i+1) and the air output Q i of each cross section of each pipe section comprise the following steps:
S31, the number of pipe sections divided by the variable cross section air pipe is assumed to be n, and the cross sections from the head to the tail pipe are 0, 1,2, … … i … …, n-1, n; the pipe sections are 0-1, 1-2 and … … i- (1+1) … …, (n-1) -n;
s32, calculating the length L m of each pipe section of the variable cross-section air pipe;
Lm＝Lb/n
L m, the length of each pipe section of the variable cross-section air pipe, m;
L b, the maximum length of the variable cross-section air pipe which can be arranged, m;
n-the number of pipe sections divided by the variable cross section air pipe is planned;
s33, calculating the air output Q m of each pipe section of the variable cross-section air pipe;
Qm＝Q/n
Q m -the air output of each pipe section of the variable cross-section air pipe, m 3/s;
S34, calculating the air quantity Q i of each section of the variable-section air pipe and the air quantity Q i-(i+1) of each pipe section;
Qi＝Q-Qm×i
Qi-(i+1)＝Q-Qm×i
Q i -the air quantity of each section of the variable-section air pipe, wherein the value range of i is 0 to n, m 3/s;
Q i-(i+1) -the air quantity of each pipe section of the variable cross-section air pipe, m 3/s.
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