CN114580124A

CN114580124A - Design method for variable-section uniform air supply pipeline of rail transit vehicle

Info

Publication number: CN114580124A
Application number: CN202210208696.1A
Authority: CN
Inventors: 王友君
Original assignee: Shanghai Ocean University
Current assignee: Shanghai Ocean University
Priority date: 2022-03-04
Filing date: 2022-03-04
Publication date: 2022-06-03
Anticipated expiration: 2042-03-04
Also published as: CN114580124B

Abstract

The invention discloses a method for designing a variable-section uniform air supply pipeline of a rail transit vehicle, which comprises the following steps of: s1, dividing air conditioner zones, and determining necessary parameters and limiting conditions for designing an air supply pipeline; s2, calculating the wind speed v of the minimum section wind pipe of the air supply pipeline_r(ii) a S3, setting the number of pipe sections divided by the variable cross-section air pipe to be n; s4, calculating the minimum width w of the air outlet_omin(ii) a S5, calculating the minimum sectional area S of the section 0 of the variable-section air pipe_0min(ii) a S6, calculating the minimum conveying power delta P of the air supply branch pipeline_emin(ii) a S7, calculating the width w of the air outlet_o(ii) a S8, calculating the sectional area S of each section of the variable-section air supply pipeline_iHeight H_iWidth W_i. The method can be used for not only designing the variable cross-section air supply pipeline of the vehicle ventilation air-conditioning system, but also evaluating the finished variable cross-section air supply pipeline of the vehicle ventilation air-conditioning system. The invention can also be used in other engineering fields.

Description

Design method for variable-section uniform air supply pipeline of rail transit vehicle

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-section uniform air supply pipeline of a rail transit vehicle.

Background

In the air conditioning system of the rail transit vehicle, an air supply pipeline is an intermediate link for connecting an air processing unit and a carriage passenger room. Whether the designed air output can be uniformly delivered into the passenger room or not is important for realizing reasonable air flow organization distribution of the passenger room and ensuring the air quality of the passenger room. With regard to the uniform air supply of rail transit vehicles, the technical results disclosed in foreign countries are relatively few, and china tries active research and development while introducing foreign technologies.

Document one (Chenjian cloud, zang subway train air conditioning uniform supply air duct overview [ J ] refrigeration, 2017, 36 (141): 53-59.) points out: at present, the air supply pipelines adopted by rail transit vehicles at home and abroad are mainly of 4 types: circular tube 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 tube type air supply pipeline is an air pipe which determines the pipe diameters of different pipe sections by carrying out detailed resistance calculation and test section by section so as to meet the air supply requirements of different positions. Document two (Longjing, King Shuao. subway vehicle air conditioning system air supply duct analysis [ J ]. electric locomotives and urban rail vehicles, 2004, 27 (4): 40-42.) states: this type of air duct is used in many foreign rail vehicles, for example: vienna subway, melbourne subway, newcastle subway, oslo subway. However, the whole design, manufacture and construction process of the subway train is more complicated, and domestic subways only adopt the air pipes of the type in individual lines, such as: guangzhou subway line III and Shanghai pearl line II.

(2) The large-section quasi-static-pressure air supply pipeline is an equal-section air pipe which can realize quasi-uniform air supply based on the principle that the cross-sectional area of the air pipe is large enough, the dynamic pressure in the air pipe is small, the static pressure is large and the change along the way is small. The large-section quasi-static pressure air supply pipeline is more suitable for vehicles with larger roof space, such as railway passenger cars and subway A-type vehicles. The structural characteristics and the design method of the air duct of the domestic A-type vehicle adopting the static pressure principle are introduced in the third document (Zhou-survivor, vehicle city sword, design analysis of the air duct of the domestic subway type vehicle air-conditioning system [ J ]. urban rail transit research, 2008, (9):36-39.), and further numerical simulation results show that: because of the limitation of the size of the A-type vehicle, the air duct is not static pressure in the complete sense, thereby having adverse effect on the uniformity of the outlet air.

(3) A strip slit type static pressure air supply pipeline is an improvement on a subway vehicle air supply pipeline by using the design idea of large-section quasi-static pressure air supply of a railway passenger car. The fourth document (Wang Shuao, talking over, development of air-conditioned passenger car uniform air supply duct [ J ]. railway vehicle, 1992, (8): 112- & 114 ]) states that: most of domestic subway vehicles generally adopt a strip-seam type static pressure air supply pipeline, such as: the subway train comprises subway vehicles in cities such as Changchun, Dalian, Beijing, Tianjin, Nanjing and Shanghai. The results of researches on the performance of the fifth document (Yang evening passenger car air conditioner static pressure uniform air supply duct and the development of an inducer [ D ]. Qingdao Islands: Qingdao institute of architecture engineering, 2002), the sixth document (Liuyang, Yikou, Li Yiming. design of air outlet uniformity of a subway vehicle air duct system [ J ]. electric locomotives and urban rail vehicles, 2011, 32 (1): 48-50.), and the seventh document (Yijiabi, Wangxiang, Shiyi, etc.. the uniform air supply duct for subway trains: CN201020298338.7[ P ].2011-07-20 ]) show that: due to the limitation of the size of an actual subway vehicle, the sectional area of an air duct cannot be large enough, and the air duct cannot realize static pressure air supply in the true sense. In practical engineering, the slit type static pressure air supply pipeline has to adopt a method of changing the shape and the size of an air outlet or arranging a block in an air duct to improve the air supply uniformity. Therefore, certain difficulties are brought to design, manufacture and construction.

(4) The novel variable cross-section air supply pipeline is an air pipe type which realizes uniform air supply by changing the sectional area of the air supply pipeline, enabling the dynamic pressure difference to overcome resistance and keeping the static pressure of the pipeline unchanged. 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 the CFD technology, research on variable-section air supply pipelines is carried out on eight documents (Wang Liu. air supply duct of subway coach air conditioner and airflow organization optimization research in passenger room [ D ]. Wuhan: China university of science and technology, 2008), nine documents (Mayinhong. air supply duct air outlet performance numerical simulation and optimization [ D ]. Wuhan: China university of science and technology, 2008.), ten documents (Suwei Hua, Wu V, Zhangliang, and the like. optimization research on the internal structure of variable-section air duct of subway train [ J ]. report on railroad science and engineering, 2021, 18 (8): 2137 + 2144.). However, the results of the past studies have had the following drawbacks: : (a) it is impossible to judge whether the air volume born by the air supply duct is reasonable. (b) The pipeline is still internally provided with baffles or flow deflectors and other barriers, and the advantage of uniform air supply with variable cross sections is not fully exerted. (c) The selection of the cross-sectional dimension and the change ratio is random and empirical, and a calculation method of the cross-sectional dimension and the change ratio cannot be given. (d) The past optimization scheme only aims at a specific engineering project, and when a new project and a new vehicle model meet the specific engineering project, a great amount of manpower and time are needed for scheme trial and comparison, so that the optimal design cannot be given in one step. (e) The CFD technology has high requirements on professional quality of designers, and the skilled application of the CFD technology needs to be proficient in the capabilities of high hydrodynamics, high heat transfer, computer programming and the like, so that the requirement on quick engineering design cannot be met.

In summary, the variable cross-section uniform air supply pipeline is an advanced concept, but a design method which meets the rapid engineering requirement is not provided.

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 vehicles of various scales, avoid adding a resistor in the pipeline, reduce the conveying resistance and energy consumption, judge whether the maximum flow speed in the pipeline, the maximum layout area of an air outlet, the maximum layout area of a variable cross-section pipeline, the minimum conveying power of an air supply branch and even the air conditioner partition born by the air supply branch are reasonable or not, provide a calculation method of the cross-section dimension and the change proportion of the variable cross-section pipeline, realize the completely meaningful static pressure air supply and meet the requirement of rapid engineering design.

The invention is realized by the following technical scheme:

a method for designing a variable-section uniform air supply pipeline of a rail transit vehicle comprises the following steps:

s1, dividing air conditioner zones, and determining necessary parameters and limiting conditions for designing an air supply pipeline;

s2, calculating the wind speed v of the minimum section wind pipe of the air supply pipeline_rJudgment of v_rWhether the maximum allowable wind speed v is exceeded_rmax；

If v appears in step S2_r≤v_rmaxCarrying out the next step; if v is_r＞v_rmaxIf so, the branch is judged to bear too large air supply volume and the air conditioner is not reasonable in partition, and the step returns to the step S1;

s3, drawing the number of the pipe sections divided by the variable cross-section air pipe to be n, and calculating the air quantity Q of each cross section_iAnd length L of each pipe section_mAir volume Q_mSum air quantity Q_i-(i+1)；

S4, calculating the minimum width w of the air outlet_ominJudgment of w_ominWhether or not to exceed the maximum width w of the air outlet which can be arranged_ob；

If w appears in step S4_omin≤w_obCarrying out the next step; if w is_omin＞w_obIf so, the branch is judged to bear too large air supply volume and the air conditioner is not reasonable in partition, and the step returns to the step S1;

s5, calculating the minimum sectional area S of the section 0 of the variable-section air pipe_0min(ii) a Judgment S_0minWhether the maximum cross-sectional area S which can be arranged by the variable cross-section air pipe is exceeded_b；

If S appears in step S5_0min≤S_bCarrying out the next step; if S is_0min＞S_bIf so, the branch is judged to bear too large air supply volume and the air conditioner is not reasonable in partition, and the step returns to the step S1;

s6, calculating the minimum conveying power delta P of the air supply branch pipeline_eminJudgment of Δ P_eminWhether the maximum full pressure Δ P of the alternative power plant is exceeded_bmax；

If Δ P occurs in step S6_emin≤ΔP_bmaxCarrying out the next step; if Δ P_emin＞ΔP_bmaxIf the pressure is too high, the air conditioner is not reasonable in partition, and the process returns to step S1;

s7, calculating the width w of the air outlet_o；

S8, calculating the sectional area S of each section of the variable-section air supply pipeline_iHeight H_iWidth W_iThe ratio of change k in the height of the cross section of each pipe section_H[(i-(i+1)]And the variation ratio k of the cross-sectional width_W[(i-(i+1)]And the conveying power delta P of the air supply branch pipeline_e。

Preferably, the necessary parameters and the limiting conditions for designing the blowing duct in step S1 include the following: total air supply Q born by air supply pipeline and sectional area S of branch minimum section air pipe_rHigh H_rWidth W of_rAnd length L_rThe ratio of protrusion of the inlet of the minimum cross-section air duct C_tMaximum allowable wind speed v of air supply duct_rmaxMaximum sectional area S where variable cross-section air pipes can be arranged_bHigh H_bWidth W_bAnd length L_bPipe material for air supply duct, type of air outlet and maximum area f that can be arranged_obWidth w_obLength l, length l_obMaximum full pressure Δ P of optional power plant_bmax。

Preferably, v in the step S2_rThe calculation method comprises the following steps:

v_r＝Q/S_r

v_r-wind speed of the minimum cross section wind pipe, m/s;

q-total air supply volume, m, born by the air supply branch pipeline³/s；

S_r-cross-sectional area, m, of the minimum cross-sectional air duct of the air supply branch²。

Preferably, the method for determining the number of each section and each pipe section and the length L of each pipe section in the step S3_mAir volume Q_mSum air quantity Q_i-(i+1)And the air quantity Q of each section_iThe calculation method comprises the following steps:

s31, setting the number of pipe sections divided by the variable cross-section air pipe to be n, wherein the cross sections of the pipe sections from the head to the tail are 0, 1, 2, … … i … …, n-1 and n; the pipe sections are 0-1, 1-2, … … i- (1+1) … …, (n-1) -n;

s32, calculating the length L of each pipe section of the variable cross-section air pipe_m；

L_m＝L_b/n

L_m-the length, m, of each section of the variable cross-section air duct;

L_bthe maximum length, m, that the variable cross-section air duct can be arranged;

n is the number of the pipe sections divided by the wind pipe with the planned variable cross section;

s33, calculating the air output Q of each section of the variable cross-section air pipe_m；

Q_m＝Q/n

Q_mAir output of each section of the variable cross-section air pipe, m³/s；

S34, calculating air quantity Q of each section of the variable-section air pipe_iAnd the air quantity Q of each pipe section_i-(i+1)；

Q_i＝Q-Q_m×i

Q_i-(i+1)＝Q-Q_m×i

Q_iThe value range of the air volume of each section of the variable-section air pipe, i is 0 to n, m³/s；

Q_i-(i+1)The air volume m of each section of the variable cross-section air duct³/s。

Preferably, the minimum width w of the air outlet in the step S4_ominThe calculation method comprises the following steps:

s41, determining the maximum allowable flow velocity v of the air outlet of the passenger compartment of the carriage according to the air supply requirement of the passenger compartment of the carriage_omax；

S42, according to the maximum allowable flow velocity v of the air outlet_omaxCalculating the minimum area f of the air outlet_omin；

f_omin＝Q/v_omax

f_ominMinimum area of the outlet, m²；

v_omax-the maximum allowable flow velocity at the outlet, m/s;

s43, according to the minimum area f of the air outlet_ominAnd the air outlet can be arranged_obCalculating the minimum width w of the air outlet_omin；

w_omin＝f_omin/l_ob

w_omin-minimum width of the outlet, m;

l_obthe maximum length, m, that the air outlet can be arranged.

Preferably, the minimum cross-sectional area S of the section 0 in the step S5_0minThe calculation method comprises the following steps:

s51, setting up the maximum allowable flow velocity v of the air outlet_omax；

S52, drawing up the minimum outflow angle alpha of the air outlet_minDetermining the outflow coefficient mu;

s53, according to the maximum allowable flow velocity v of the air outlet_omaxAnd the outflow coefficient mu, calculating the maximum static pressure velocity v of the air outlet_jmax；

v_jmax＝v_omax/μ

v_jmax-the maximum static pressure velocity of the outlet, m/s;

mu-flow coefficient of the air outlet;

s54, according to the maximum static pressure velocity v of the air outlet_jmaxCalculating the maximum static pressure P of the air outlet_jmax；

P_jmax＝ρv_jmax ²/2

P_jmax-the maximum static pressure, Pa, of the air outlet;

rho-density of fluid transported in pipeline, kg/m³Air is 1.20kg/m³；

S55, according to the maximum static pressure velocity v of the air outlet_jmaxAnd a minimum outflow angle α_minCalculating the maximum dynamic pressure velocity v of the cross section 0_0dmax；

v_0dmax＝v_jmax/tan(α_min)

v_0dmax-maximum dynamic pressure velocity of section 0, m/s;

s56, according to the maximum dynamic pressure velocity v of the section 0_0dmaxCalculating the minimum cross-sectional area S of the cross-section 0_0min；

S_0min＝Q/v_0dmax

S_0minMinimum cross-sectional area of section 0, m²。

Preferably, Δ P in step S6_eminThe calculation method comprises the following steps:

s601. according to the height H of the air pipe with the minimum section_rAnd width W_rCalculating the flow equivalent diameter D of the branch minimum section air pipe_r；

D_rFlow velocity equivalent diameter, m, of the smallest cross section air duct (flexible coupling duct);

W_r-flexible jointThe width of the air receiving pipe is m;

H_r-height, m, of the flexible connecting duct;

s602. according to the air quantity Q and the flow equivalent diameter D of the flexible connecting air pipe_rChecking the specific friction resistance R of the flexible connecting air pipe_r；

S603, according to the specific friction resistance R of the flexible connection air pipe_rAnd length L_rCalculating the on-way resistance delta P of the flexible connecting air pipe_ry；

ΔP_ry＝R_r×L_r

ΔP_ryThe on-way resistance of the flexible connecting air pipe is Pa/m;

R_rthe specific friction resistance of the flexible connecting air pipe is Pa/m;

L_r-length of flexible coupling duct, m;

s604, according to the wind speed v of the flexible connection air pipe_rCalculating the dynamic pressure P of the flexible connecting air pipe_rd；

P_rd＝ρv_r ²/2

P_rd-dynamic pressure, Pa, of the flexible connecting duct;

s605. according to the sudden shrinkage ratio C of the inlet of the flexible connecting air pipe_tsChecking the local resistance system epsilon of the sudden shrinkage of the inlet of the flexible connecting air pipe_rCounting;

s606, according to the local resistance system epsilon of the flexible connection air pipe inlet sudden shrinkage_rNumber and dynamic pressure P_rdCalculating the local resistance delta P of the flexible connecting air pipe_rj；

ΔP_rj＝ε_r×P_rd

ΔP_rj-local resistance, Pa, of the flexible connecting duct;

ε_r-a local resistance system of the flexible connection air duct for the sudden contraction of the inlet;

s607, according to the on-way resistance delta P of the flexible connecting air pipe_ryAnd local resistance Δ P_rjCalculating the total resistance delta P of the flexible connecting air pipe_r；

ΔP_r＝ΔP_ry+ΔP_rj

ΔP_r-the total resistance of the flexible connecting duct, Pa;

s608, according to the air quantity Q of the section 0 of the variable-section air pipe₀And a maximum cross-sectional area S that can be arranged_bCalculating the minimum dynamic pressure velocity v of the cross section 0_0dmin；

v_0dmin＝Q/S_b

v_0dmin-minimum dynamic pressure velocity of section 0, m/s;

s609, according to the minimum dynamic pressure velocity v of the section 0_0dminCalculating the minimum dynamic pressure P of the cross section 0_0dmin；

P_0dmin＝ρv_0dmin ²/2

P_0dmin-minimum dynamic pressure, Pa, of section 0;

s610, according to the minimum outflow angle alpha of the air outlet of the pipe section 0-1_minDetermining the outflow coefficient mu of the air outlet of the pipe section 0-1;

s611, according to the minimum dynamic pressure velocity v of the section 0_0dminAnd the minimum outflow angle alpha of the air outlet_minCalculating the minimum hydrostatic velocity v_jmin；

v_jmin＝v_0dmin×tan(α_min)

v_jmin-minimum static pressure velocity, m/s, of the pipe section 0-1 air outlet;

s612, according to the minimum static pressure velocity v of the air outlet_jminCalculating the minimum static pressure P of the air outlet_jmin；

P_jmin＝ρv_jmin ²/2

P_jmin-minimum static pressure, Pa, of the air outlet;

s613, calculating sudden expansion ratio C of section 0 inlet (soft connection outlet)_tk；

C_tk＝A₀/A₁

A₀The cross-sectional area, m, of the small-section pipe at the sudden expansion or contraction²；

A₁The cross-sectional area, m, of the large-section pipe at the sudden expansion or contraction²；

S614, according to the sudden expansion ratio C of the section 0 inlet (soft connection outlet)_tkChecking the local resistance system epsilon of the section 0₀Counting;

s615, according to the local resistance system epsilon of the section 0₀Number and minimum dynamic pressure P_0dminCalculating the minimum local resistance DeltaP of the section 0_0jmin；

ΔP_0jmin＝ε₀×P_0dmin

ΔP_0jmin-minimum local resistance of section 0, Pa;

ε₀-local drag coefficient of section 0;

s616, according to the minimum dynamic pressure P of the section 0_0dminMinimum local resistance Δ P_0jminAnd minimum static pressure P of air outlet_jminAnd, calculating the minimum total pressure P of the section 0_0qmin；

P_0qmin＝P_0dmin+ΔP_0jmin+P_jmin

P_0qmin-minimum total pressure, Pa, of section 0;

s617, determining resistance delta P of other irregular local resistance components_x；

S618, determining the minimum margin K of the conveying power of the air supply branch_min；

S619, according to the total resistance delta P of the flexible connection air pipe_rMinimum total pressure P of section 0_0qminResistance Δ P of other irregular local resistance members_xAnd a minimum margin K of power delivered_minCalculating the minimum conveying power delta P of the air supply branch_emin；

ΔP_emin＝(1+K_min)×(ΔP_r+P_0qmin+ΔP_x)

ΔP_emin-minimum delivery power, Pa, of the air supply branch;

K_min-the minimum richness of the delivery power of the air supply branch;

ΔP_x-the resistance, Pa, of other irregular local resistance members.

Preferably, the width w of the air outlet in the step S7_oThe calculation method comprises the following steps:

s71, drawing up an average outflow speed v of an air outlet according to the requirement of a passenger compartment of a carriage on an air supply speed_o；

S72, setting the average outflow speed v of the air outlet according to the drawing_oCalculating the total area f of the air outlet_o；

f_o＝Q/v_o

f_oTotal area of the outlet, m²；

v_o-drawing up the average outflow speed of the air outlet in m/s;

s73, setting up the length l of the air outlet_o；

S74, according to the total area f of the air outlet_oAnd a proposed length l_oCalculating the width w of the air outlet_o；

w_o＝f_o/l_o

w_oWidth of the outlet, m.

Preferably, in the step S8, the sectional area S of each section of the variable-section blowing duct_iHeight H_iWidth W_iThe ratio of change k in the height of the cross section of each pipe section_H[(i-(i+1)]And the variation ratio k of the cross-sectional width_W[(i-(i+1)]And the conveying power delta P of the air supply branch pipeline_eThe calculation method comprises the following steps:

s801, drawing up the outlet flow speed v of the air outlet according to the air supply requirement of the passenger room_o；

S802, calculating the relative flow Q of the air outlet of the pipe section 0-1_m-0A ratio;

Q_m-0＝Q_m/Q_0-1

Q_m-0-relative flow of the pipe segment 0-1 outlet;

Q_0-1air volume of pipe section 0-1, m³/s；

S803, drawing up an air outlet outflow angle alpha according to the air supply requirement of the passenger room;

s804, according to the relative flow Q of the air outlet of the pipe section 0-1_m-0And angle of outflowAlpha, determining the outflow coefficient mu;

s805, according to the outflow speed v of the air outlet_oAnd the outflow coefficient mu, calculating the static pressure velocity v of the air outlet_j；

v_j＝v_o/μ

v_j-the static pressure velocity of the outlet, m/s;

mu-outflow coefficient of the air outlet;

v_o-drawing up the outflow speed of the air outlet in m/s;

s806. according to the static pressure velocity v of the air outlet_jCalculating the static pressure P of the tuyere_j；

P_j＝ρv_j ²/2

P_j-static pressure, Pa, of the air outlet;

s807. according to the static pressure velocity v of the air outlet_jAnd drawing up the outflow angle alpha to calculate the dynamic pressure velocity v of the cross section 0_0d；

v_0d＝v_j/tanα

v_0d-dynamic pressure velocity of section 0, m/s;

alpha-drawing up an outflow angle alpha of the air outlet;

s808, dynamic pressure velocity v according to section 0_0dSum flow rate Q₀Calculating the sectional area S of the section 0₀Judgment S₀And S_bThe relative size of (d);

S₀＝Q₀/v_0d

S₀section area of section 0, m²；

If S in step S808₀≤S_bCarrying out the next step; if S is₀＞S_bReturning to step S801;

s809, drawing up the height H of the section 0₀；

S810, according to the height H of the planned section 0₀And cross-sectional area S₀Calculating the width W of the cross section 0₀；

W₀＝S₀/H₀

W₀Width of section 0, m;

S₀area of cross-section 0, m²；

H₀Height of section 0, m;

s811 dynamic pressure velocity v according to section 0_0dCalculating dynamic pressure P of section 0_0d；

P_0d＝ρv_0d ²/2

P_0d-dynamic pressure, Pa, of section 0;

s812, calculating sudden expansion ratio C of inlet (soft connection outlet) of section 0_tk；

C_tk＝A₀/A₁

S813, according to the sudden expansion ratio C of the inlet (soft connection outlet) of the section 0_tkChecking the sudden expansion local resistance system epsilon of the section 0₀Counting;

s814, sudden expansion local resistance system epsilon according to section 0₀Number and dynamic pressure P_0dCalculating the sudden expansion local resistance P of the section 0_0j；

P_0j＝ε₀×P_0d

P_0j-sudden local resistance, Pa, of section 0;

ε₀-sudden expansion local drag coefficient of section 0;

s815. dynamic pressure P according to section 0_0dStatic pressure P_jAnd sudden local resistance P_0jCalculating the total pressure P of the cross section 0_0q；

P_0q＝P_j+P_0d+P_0j

P_0q-full pressure, Pa, of section 0;

s816, determining the resistance delta P of other irregular local resistance components_x；

S817, determining the abundance K of the conveying power of the air supply branch;

s818, according to total resistance delta P of the flexible connection air pipe_rFull pressure P of section 0_0qResistance Δ P of other irregular local resistance members_xAnd the margin K of the conveying power, and calculating the conveying power delta P of the air supply branch_eJudgment of Δ P_eWhether the judgment is reasonable or not;

ΔP_e＝(1+K)×(ΔP_r+P_0q+ΔP_x)

ΔP_ethe conveying power Pa of the air supply branch;

k is the margin of the power delivered by the air supply branch;

ΔP_x-the resistance of other irregular local resistance members, Pa;

if Δ P in step S818_e≤ΔP_bmaxThe design is reasonable, and the next step is carried out; if Δ P_e＞ΔP_bmaxIf the design is not reasonable, go back to step S801;

s819. Width W according to section 0₀And high H₀Calculating the flow equivalent diameter D of the cross section 0₀；

D₀Flow equivalent diameter, m, of section 0;

W₀width of section 0, m;

H₀height of section 0, m;

s820, according to air quantity Q of pipe section 0-1_0-1Flow equivalent diameter D of section 0₀For an approximation of the pipe section 0-1, the specific friction resistance R of the pipe section 0-1 is examined_(0-1)；

S821. according to the specific friction resistance R of the pipe section 0-1_(0-1)And length L_mCalculating the on-way resistance delta P of the pipe section 0-1_(0-1)y；

ΔP_(0-1)y＝R_(0-1)×L_m

ΔP_(0-1)yBy the path of the pipe section 0-1Resistance, Pa;

R_(0-1)-specific friction resistance of pipe section 0-1, Pa/m;

s822, according to the relative flow Q of the air outlet of the pipe section 0-1_m-0Checking the local drag coefficient epsilon of the 0-1 straight-through part of the pipe section_(0-1)；

S823. dynamic pressure P according to section 0_0dAnd the local drag coefficient epsilon of the 0-1 through part of the pipe section_(0-1)Calculating the local resistance delta P of the pipe section 0-1_(0-1)j；

ΔP_(0-1)j＝ε_(0-1)×P_0d

ΔP_(0-1)j-local resistance, Pa, of the pipe section 0-1;

ε_(0-1)-local drag coefficient of pipe section 0-1;

s824, total pressure P according to section 0_0qOn-way resistance delta P of pipe section 0-1_(0-1)yAnd local resistance Δ P_(0-1)jCalculating the total pressure P of the section 1_1q；

P_1q＝P_0q-(ΔP_(0-1)y+ΔP_(0-1)j)

P_1q-full pressure, Pa, of section 1;

s825. according to the total pressure P of the section 1_1qAnd static pressure P for keeping air supply from the air outlet uniform_jCalculating the dynamic pressure P of the section 1_1dJudgment of P_1dWhether the judgment is reasonable or not;

P_1d＝P_1q-P_j

P_1d-dynamic pressure, Pa, of section 1;

if P is in step S825_1dThe design is reasonable, and the next step is carried out; if P is_1dIf not more than 0, the design returns to step S801;

s826. dynamic pressure P according to section 1_1dCalculating the dynamic pressure velocity v of the cross section 1_1d；

v_1d-dynamic pressure velocity of section 1, m/s;

s827. dynamic pressure velocity v according to section 1_1dSum air quantity Q₁Calculating the sectional area S of the section 1₁；

S₁＝Q₁/v_1d

S₁Section area of section 1, m²；

S828, drawing up the height H of the section 1₁；

S829, cross-sectional area S according to section 1₁And a predetermined height H₁Calculating the width W of the cross section 1₁；

W₁＝S₁/H₁

H₁Height of section 1, m;

W₁width of section 1, m;

s830, according to the height H of the section 0₀And height H of cross section 1₁Calculating the change ratio k of the section height of 0-1 of the pipe section_H(0-1)；

k_H(0-1)＝H_1/H₀

k_H(0-1)-the ratio of the variation of the height of the section 0-1 of the pipe section;

s831. according to the width W of the section 0₀And the width W of the cross section 1₁Calculating the variation ratio k of the section width of 0-1 of the pipe section_W(0-1)；

k_W(0-1)＝W_1/W₀

k_W(0-1)-the ratio of variation of the section width of the pipe section 0-1;

s832, repeating the steps S819-S831 to calculate the height H of the subsequent section_iAnd width W_iThe ratio k of the change in the cross-sectional height of the subsequent tube section_H[i-(i+1)]And the variation ratio k of the cross-sectional width_W[i-(i+1)]；

If the subsequent tube section employs the same ratio of change in cross-sectional height and change in cross-sectional width as the preceding adjacent tube section, then, in some cases,

H_i＝H_(i-1)×k_H[(i-1)-i]

W_i＝W_(i-1)×k_W[(i-1)-i]

H_i-height of section i, m;

k_H[(i-1)-i]tube section [ (i-1) -i)]The cross-sectional height variation ratio of (a);

W_ithe width of the section i, m;

k_W[(i-1)-i]tube section [ (i-1) -i)]The cross-sectional width change ratio of (a).

Has the advantages that: compared with the traditional equal-section conveying pipeline, the pipeline can adapt to vehicles with various scales; compared with the traditional variable cross-section air supply pipeline, the variable cross-section air supply pipeline has the advantages that 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 pipeline, the static pressure uniform air supply can be realized; compared with a CFD simulation method, the method can adapt to the requirement of rapid engineering;

in addition, the invention also provides a calculation method for judging whether the maximum flow velocity in the pipeline, the maximum layout area of the air outlet, the maximum layout sectional area of the variable-section pipeline, the minimum conveying power of the air supply branch and even the air conditioner subareas borne by the air supply branch are reasonable or not and the section scale and the change proportion of the variable-section pipeline, thereby avoiding the blindness and the heuristics of the past design method, saving the material cost and the time cost required by the test, and providing an optimization scheme with uniform air supply and low operation energy consumption;

the method can be used for not only designing the variable cross-section air supply pipeline of the vehicle ventilation air-conditioning system, but also evaluating the finished variable cross-section air supply pipeline of the vehicle ventilation air-conditioning system. The invention can also be used for the design and evaluation of uniform and non-uniform outflow ducts for other vehicles, other spaces, other equipment, other fluids, other engineering fields, other outlet types.

Drawings

FIG. 1 is a schematic view of a No. 1 branch variable cross-section air supply pipeline of an air conditioning system of a certain subway train in Shanghai, which is designed by the invention.

Fig. 2 is a general technical route diagram of the present invention.

FIG. 3 is a technical schematic diagram of step S3 according to the present invention.

FIG. 4 is a technical scheme of step S4 according to the present invention.

FIG. 5 is a technical schematic diagram of step S5 according to the present invention.

FIG. 6 is a technical schematic diagram of step S6 according to the present invention.

FIG. 7 is a technical schematic diagram of step S7 according to the present invention.

FIG. 8 is a technical schematic diagram of step S8 according to the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

As shown in fig. 1-8:

example I, design of No. 1 branch variable cross-section air supply pipeline of air conditioning system of Shanghai subway train

the total air supply quantity Q born by the No. 1 branch air supply pipeline of the air conditioning system of a certain subway train of Shanghai subway is 800m³/h(0.22m³S); cross-sectional area S of branch minimum cross-section air pipe (i.e. flexible connection air pipe, uniform cross-section)_r＝0.03m²High H_r0.10m wide W_r0.30m and length L_r2.00m, the projecting and shrinking ratio C of the inlet of the air pipe with the minimum section_ts0.4; maximum allowable wind speed v_rmaxMaximum section area S which can be arranged in the variable section air pipe of 10m/S_b＝0.12m²High H_b0.15m, width W_b0.80m and length L_b4.60 m; the pipes of the air supply pipeline are made of common galvanized steel sheets; the air outlet is strip-shaped, and the maximum area f of the air outlet can be arranged_ob＝1.38m²Width w_ob0.30m long_ob4.60 m; maximum full pressure Δ P for alternative power plants_bmax＝100pa；

v_r＝Q/S_r＝0.22÷0.03＝7.33m/s

v_r-wind speed of the minimum cross section wind pipe, m/s;

q-total air supply volume, m, born by the air supply branch pipeline³/s；

S_r-cross-sectional area, m, of the minimum cross-sectional air duct of the air supply branch²；

(v_r＝7.33m/s)＜(v_rmax10m/s), the next step is carried out;

s3, setting the number of the pipe sections divided by the variable cross-section air pipe to be n, and calculating the air quantity Q of each cross section_iAnd length L of each pipe section_mAir output Q_mSum air quantity Q_i-(i+1)；

S31, setting the number of pipe sections divided by the designed variable-section air pipe to be n-2, wherein the sections of the pipe from the head to the tail are 0, 1 and 2, and the pipe sections are 0-1 and 1-2;

L_m＝L_b/n＝4.6/2＝2.3m

L_m-the length, m, of each section of the variable cross-section air duct;

L_b-the maximum length, m, that the variable cross-section air duct can be arranged;

Q_m＝Q/n＝0.22/2＝0.11m³/s

Q_mAir output of each section of the variable cross-section air duct, m³/s；

Q₀＝Q＝0.22m³/s

Q₁＝Q-Q_m×i＝0.22-0.11×1＝0.11m³/s

Q₂＝Q-Q_m×i＝0.22-0.11×2＝0m³/s

Q_0-1＝Q＝0.22m³/s

Q_1-2＝Q-Q_m×i＝0.22-0.11×1＝0.11m³/s

Q_i-(i+1)The air volume m of each section of the variable cross-section air duct³/s；

S41, determining the maximum allowable flow velocity v of an air outlet of a carriage passenger room according to the air supply requirement of the carriage passenger room_omax＝2.0m/s；；

f_omin＝Q/v_omax＝0.22/2.0＝0.11m²

f_ominMinimum area of the outlet, m²；

v_omax-the maximum allowable flow velocity at the outlet, m/s;

w_omin＝f_omin/l_ob＝0.11/4.6＝0.02m

w_omin-minimum width of the outlet, m;

l_obthe maximum length, m, at which the outlet can be arranged;

(w_omin0.02m)＜(w_ob0.30m), the next step was performed;

s5, calculating the minimum sectional area of the section 0 of the variable-section air pipeS_0min(ii) a Judgment S_0minWhether the maximum sectional area S of the variable-section air pipe which can be arranged is exceeded_b；

S51, setting up the maximum allowable flow velocity v of the air outlet_omax＝2.00m/s；

S52, drawing up the minimum outflow angle alpha of the air outlet_minDetermining an outflow coefficient mu;

setting the minimum outflow angle alpha of the air outlet_min60 degrees, investigate the outflow coefficient of sharp-edged orifice in fig. 4-1-6, compiled by xiaoyun encourage (fourth edition), fluid distribution network (fluid distribution network), to obtain μ 0.6;

v_jmax＝v_omax/μ＝2.00/0.6＝3.33m/s

v_jmax-the maximum static pressure velocity of the outlet, m/s;

mu-flow coefficient of the air outlet;

P_jmax＝ρv_jmax ²/2＝1.20×(3.33m/s)²/2＝6.65Pa

P_jmax-the maximum static pressure, Pa, of the air outlet;

rho-density of fluid transported in pipeline, kg/m³Air is 1.20kg/m³；

v_0dmax＝v_jmax/tan(α_min)＝3.33/1.73＝1.92m/s

v_0dmax-maximum dynamic pressure velocity of section 0, m/s;

S_0min＝Q/v_0dmax＝0.22/1.92＝0.11m²

S_0minMinimum cross-sectional area of section 0, m²；

(S_0min＝0.11m²)＜(S_b＝0.12m²) Carrying out the next step;

W_r-the width of the flexible connecting duct, m;

H_r-height of the flexible connecting duct, m;

According to the air quantity Q of the flexible connecting air pipe is 0.22m³S and flow equivalent diameter D_r0.26m, encourage Xiaoyi folk editors (fourth edition) in the section of fluid distribution pipe network (3-6-1), R can be known as the linear calculation of frictional resistance per unit length of ventilation duct_r＝1.05Pa/m；

ΔP_ry＝R_r×L_r＝1.05Pa/m×2.0m＝2.10Pa

ΔP_ryThe on-way resistance of the flexible connecting air pipe is Pa/m;

L_r-length of the flexible connecting duct, m;

P_rd＝ρv_r ²/2＝1.20kg/m³×(7.33m/s)²＝64.47Pa

P_rd-dynamic pressure, Pa, of the flexible coupling duct;

s605, according to the sudden shrinkage ratio C of the inlet of the flexible connecting air pipe_tsChecking the local resistance system epsilon of the sudden shrinkage of the inlet of the flexible connecting air pipe_rCounting;

the protruding shrinkage ratio of the inlet of the flexible connecting air pipe is C_tsWhen the local resistance coefficient epsilon is 0.4, the local resistance coefficient epsilon of the sudden contraction of the inlet of the flexible connecting air pipe is obtained by looking up an appendix local resistance coefficient table of < fluid transmission and distribution pipe network (third edition) > in the auspicious encourage showy folk_rIs 0.34;

ΔP_rj＝ε_r×P_rd＝0.34×64.47Pa＝21.92Pa

ΔP_rj-local resistance, Pa, of the flexible connecting duct;

ΔP_r＝ΔP_ry+ΔP_rj＝2.10Pa+21.92Pa＝24.02Pa

ΔP_r-the total resistance of the flexible connecting duct, Pa;

v_0dmin＝Q/S_b＝0.22m³/s÷0.12m²＝1.83m/s

v_0dmin-minimum dynamic pressure velocity of section 0, m/s;

P_0dmin＝ρv_0dmin ²/2＝1.2kg/m³×(1.83m/s)²÷2＝2.01Pa

P_0dmin-minimum dynamic pressure, Pa, of section 0;

according to the minimum outflow angle alpha of the air outlet_min60 degrees, find out and pay encourage shu yi shi mai compiled "fluid distribution network (fourth edition)" fig. 4-1-6 sharp edge orifice outflow coefficient, get μ 0.6;

v_jmin＝v_0dmin×tan(α_min)＝v_0dmin×1.73＝1.83m/s×1.73＝3.17m/s

P_jmin＝ρv_jmin ²/2＝1.2kg/m³×(3.17m/s)²÷2＝6.02Pa

P_jmin-minimum static pressure, Pa, of the air outlet;

C_tk＝A₀/A₁＝0.03m²/0.12m²＝0.25

sudden expansion ratio C of section 0 entrance_tkWhen 0.25, the inventor consults encourage Biaoyi Bianzhi (third edition) annex local resistance coefficient table to obtain local resistance coefficient epsilon₀Is 0.57;

ΔP_0jmin＝ε₀×P_0dmin＝0.57×2.01Pa＝1.15Pa

ΔP_0jmin-minimum local resistance of section 0, Pa;

ε₀-local drag coefficient of section 0;

P_0qmin＝P_0dmin+ΔP_0jmin+P_jmin＝2.01Pa+1.15Pa+6.02Pa＝9.18Pa

P_0qmin-minimum total pressure, Pa, of section 0;

Without other resistance, Δ P, in the branch_x＝0Pa；

Get K_min＝10％；

S619, according to the total resistance delta P of the flexible connection air pipe_rMinimum total pressure P of section 0_0qminResistance Δ P of other irregular local resistance members_xAnd a minimum margin K of power delivered_minCalculating the air supply branchMinimum conveying power DeltaP of road_emin；

ΔP_emin＝(1+K_min)×(ΔP_r+P_0qmin+ΔP_x)＝(1+10％)×(24.02Pa+9.18Pa+0Pa)＝36.52Pa

ΔP_emin-the minimum delivery power, Pa, of the air supply branch;

K_min-the minimum richness of the delivery power of the air supply branch;

ΔP_x-the resistance of other irregular local resistance members, Pa;

(ΔP_emin＝36.52Pa)＜(ΔP_bmax100Pa), the next step is performed;

s7, calculating the width w of the air outlet_o；

S71, drawing up an average outflow speed v of an air outlet according to the requirement of a passenger compartment of a carriage on an air supply speed_o＝1.00m/s；

f_o＝Q/v_o＝0.22m³/s÷1.00m/s＝0.22m²

f_oTotal area of the outlet, m²；

v_o-drawing up the average outflow speed of the air outlet in m/s;

s73, setting up the length l of the air outlet_o；

The maximum arrangeable length of the air outlet is taken as the length of the air outlet,/_o＝l_ob＝4.6m；

w_o＝f_o/l_o＝0.22m²÷4.6＝0.05m

w_o-width of the outlet, m;

s8, calculating the sectional area S of each section of the variable-section air supply pipeline_iHeight H_iWidth W_iSection of each pipe sectionVariation ratio k of surface height_H[(i-(i+1)]And the variation ratio k of the cross-sectional width_W[(i-(i+1)]And the conveying power delta P of the air supply branch pipeline_e；

S801, drawing up the outflow speed v of an air outlet according to the air supply requirement of a passenger room_o；

Drawing up v according to the air supply requirement of passenger room_o＝1.92m/s；

Q_m-0＝Q_m/Q_0-1＝0.11m³/s÷0.22m³/s＝0.5；

Q_m-0-relative flow at the outlet of the pipe section 0-1;

Q_0-1air volume of pipe section 0-1, m³/s；

according to the air supply requirement of the passenger room, setting alpha as 60 degrees;

s804, according to the relative flow Q of the air outlet of the pipe section 0-1_m-0And an outflow angle alpha, determining an outflow coefficient mu;

according to Q_m-00.5 and an outflow angle α of 60 °, investigating encourage the outflow coefficients of sharp-edged orifices in fig. 2-3-9 in "fluid distribution network (third edition)" by showy folks, to obtain μ of 0.6;

v_j＝v_o/μ＝1.92m/s÷0.6＝3.20m/s

v_j-the static pressure velocity of the outlet, m/s;

mu-outflow coefficient of the air outlet;

v_o-drawing up the outflow speed of the air outlet in m/s;

P_j＝ρv_j ²/2＝1.2kg/m³×(3.20m/s)²÷2＝6.14Pa

P_j-static pressure, Pa, of the air outlet;

s807, according to the static pressure velocity v of the air outlet_jAnd drawing out the flow angle alpha to calculate the dynamic pressure velocity v of the cross section 0_0d；

v_0d＝v_j/tanα＝3.20m/s÷tan60＝1.85m/s

v_0d-dynamic pressure velocity of section 0, m/s;

alpha-drawing up an outflow angle alpha of the air outlet;

S₀＝Q₀/v_0d＝0.22m3/s÷1.85m/s＝0.12m²

S₀cross section 0 cross section area, m²；

(S₀＝0.12m²)＝(S_b＝0.12m²) Carrying out the next step;

s809, drawing up the height H of the section 0₀；

Synthesis of H₀＝0.15m；

W_0＝S₀/H₀＝0.12m²÷0.15m＝0.80m

W₀Width of section 0, m;

S₀area of cross-section 0, m²；

H₀Height of section 0, m;

P_0d＝ρv_0d ²/2＝1.2kg/m³×(1.85m/s)²÷2＝2.05Pa

P_0dSection 0The dynamic pressure of (a), Pa;

C_tk＝A₀/A₁＝0.03m²/0.12m²＝0.25

P_0j＝ε₀×P_0d＝0.57×2.05Pa＝1.17Pa

P_0j-sudden local resistance, Pa, of section 0;

ε₀-sudden expansion local drag coefficient of section 0;

s815. dynamic pressure P according to section 0_0dStatic pressure P_jAnd sudden local resistance P_0jCalculating the total pressure P of the section 0_0q；

P_0q＝P_j+P_0d+P_0j＝6.14Pa+2.05Pa+1.17Pa＝9.36Pa

P_0q-total pressure of section 0, Pa;

The branch having no other resistance, Δ P_x＝0Pa；

taking K as 15%;

ΔP_e＝(1+K)×(ΔP_r+P_0q+ΔP_x)＝(1+15％)×(24.02Pa+9.36Pa+0Pa)＝38.39

ΔP_e-the delivery power of the air supply branch Pa;

k is the margin of the power delivered by the air supply branch;

ΔP_x-the resistance of other irregular local resistance members, Pa;

(ΔP_e＝38.39Pa)＜(ΔP_bmax100Pa), the next step is performed;

D₀Flow equivalent diameter, m, of section 0;

W₀width of section 0, m;

H₀height of section 0, m;

According to the air quantity Q of the pipe section 0-1_0-1＝0.22m³Flow equivalent diameter D of/s and section 0₀0.36m, Zhenxiang encourage Xiaoyi folk, in the section "fluid distribution pipe network (fourth edition)" in fig. 3-6-1, the graphic for calculating the frictional resistance per unit length of ventilation duct is known as R_(0-1)＝0.18Pa/m；

ΔP_(0-1)y＝R_(0-1)×L_m＝0.18Pa/m×2.30m＝0.41Pa

ΔP_(0-1)y-on-way resistance, Pa, of the pipe section 0-1;

R_(0-1)-specific friction resistance of pipe section 0-1, Pa/m;

According to the relative flow Q of the air outlet of the pipe section 0-1_m-00.50, the local resistance coefficient of air flowing through the straight-through part of the side hole in Table 2-3-6 compiled by Shoudu encourage Shoudu (third edition) was investigated to obtain the local resistance coefficient epsilon of the straight-through part of the pipe section 0-1_(0-1)＝0.07；

ΔP_(0-1)j＝ε_(0-1)×P_0d＝0.07×2.05Pa＝0.14Pa

ΔP_(0-1)j-local resistance, Pa, of the pipe section 0-1;

ε_(0-1)-local drag coefficient of pipe section 0-1;

P_1q＝P_0q-(ΔP_(0-1)y+ΔP_(0-1)j)＝9.36Pa-(0.41Pa+0.14Pa)＝8.81Pa

P_1q-full pressure, Pa, of section 1;

s825. according to the total pressure P of the section 1_1qAnd static pressure P for keeping air supply from the air outlet uniform_jCalculating the dynamic pressure P of the cross section 1_1dJudgment of P_1dWhether the judgment is reasonable or not;

P_1d＝P_1q-P_j＝8.81Pa-6.14Pa＝2.67Pa

P_1d-dynamic pressure, Pa, of section 1;

(P_1d2.67Pa) > 0, the design is reasonable, and the next step is carried out;

v_1d-dynamic pressure velocity of section 1, m/s;

S₁＝Q₁/v_1d＝0.11m³/s÷2.11m/s＝0.052m²

S₁Section area of section 1, m²；

S828, drawing up the height H of the section 1₁；

Defining a height H of the cross-section 1₁＝0.10m；

W₁＝S₁/H₁＝0.052m²÷0.10m＝0.52m

H₁Height of section 1, m;

W₁width of section 1, m;

k_H(0-1)＝H_1/H₀＝0.10m÷0.15m＝0.67

k_W(0-1)＝W_1/W₀＝0.52m÷0.80m＝0.65

k_W(0-1)-the ratio of variation of the section width of the pipe section 0-1;

s832, repeating the steps S819-S831 to calculate the height H of the subsequent section_iAnd width W_iThe ratio of change k in the cross-sectional height of the subsequent pipe section_H[i-(i+1)]And the variation ratio k of the cross-sectional width_W[i-(i+1)]；

The same ratio of change in the height of the cross section and the same ratio of change in the width of the cross section are used for the pipe 1-2 and the pipe 0-1, and then,

H₂＝H₁×k_H(0-1)＝0.1×0.67＝0.07m

W₂＝W₁×k_W(0-1)＝0.52×0.65＝0.34m

example two, the total air supply Q carried by the air supply duct is 1200m³/h(0.33m³S), other conditions are the same as in example one

Proceeding to S2, v will appear_r＝Q/S_r＝0.33÷0.03＝11m/s，(v_r＝7.33m/s)＞(v_rmax10m/S), the air-conditioning air area is unreasonable, the branch bears the overlarge air supply amount, and the step S1 needs to be returned to perform air-conditioning partition again;

example three, the maximum sectional area S that the variable cross section air pipe can be arranged_b＝0.08m²High H_b0.10m, other conditions and design procedure were the same as in example one

Proceeding to S56, it will appear (S)_0min＝0.11m²)＞(S_b＝0.08m²) If the air-conditioning air area is unreasonable, the branch bears overlarge air supply amount, and the step S1 is required to be returned to perform air-conditioning partition again;

the method for designing the variable-section uniform air supply pipeline of the rail transit vehicle can be applied to the design of other vehicles, other spaces, equipment and other fluids; the method can also be applied to the design of an equal-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 an exhaust pipeline; or to the evaluation of designed variable-section supply ducts.

The invention is not only used in the field of vehicle engineering, but also applicable in the engineering fields of construction, chemical engineering, environment, medicine, mine, electronics, animal husbandry and the like which need uniform fluid transportation and distribution, and the application principle and the design method are the same.

The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A method for designing a variable-section uniform air supply pipeline of a rail transit vehicle is characterized by comprising the following steps of:

s3, drawing the number of the pipe sections divided by the variable cross-section air pipe to be n, and calculating the air quantity Q of each cross section_iAnd length L of each pipe section_mAir volume Q_mAnd the air quantity Q_i-(i+1)；

If w appears in step S4_omin≤w_obProceed to the next stepA step of; if w is_omin＞w_obIf so, the branch is judged to bear too large air supply volume and the air conditioner is not reasonable in partition, and the step returns to the step S1;

s7, calculating the width w of the air outlet_o；

2. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein the step S1 includes the following steps: determining total air supply quantity Q born by air supply pipeline and sectional area S of branch minimum section air pipe_rHigh H_rWidth W of_rAnd length L_rThe ratio of protrusion of the inlet of the minimum cross-section air duct C_tMaximum allowable wind speed v of air supply duct_rmaxMaximum sectional area S where variable cross-section air pipes can be arranged_bHigh H_bWidth W_bAnd a length L_bPipe material of air supply pipeline and air outletType and maximum area f that can be arranged_obWidth w_obLength l, length l_obMaximum full pressure Δ P of optional power plant_bmax。

3. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein v in the step S2_rThe calculation method comprises the following steps:

v_r＝Q/S_r

v_r-wind speed of the minimum cross section wind pipe, m/s;

q-total air supply volume, m, born by the air supply branch pipeline³/s；

4. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein the method for determining the number of each section and each pipe section and the length L of each pipe section in the step S3_mAir volume Q_mSum air quantity Q_i-(i+1)And the air quantity Q of each section_iThe calculation method comprises the following steps:

L_m＝L_b/n

L_m-the length, m, of each section of the variable cross-section air duct;

Q_m＝Q/n

Q_m-variable cross-section air ducts eachAir output of pipe section, m³/s；

Q_i＝Q-Q_m×i

Q_i-(i+1)＝Q-Q_m×i

5. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein the minimum width w of the air outlet in the step S4_ominThe calculation method comprises the following steps:

s41, determining the maximum allowable flow velocity v of an air outlet of a carriage passenger room according to the air supply requirement of the carriage passenger room_omax；

f_omin＝Q/v_omax

f_ominMinimum area of air outlet, m²；

v_omax-the maximum allowable flow velocity at the outlet, m/s;

w_omin＝f_omin/l_ob

w_omin-minimum width of the outlet, m;

l_obthe maximum length, m, that the air outlet can be arranged.

6. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein in the step S5Minimum cross-sectional area S of cross-section 0_0minThe calculation method comprises the following steps:

s51, drawing up the maximum allowable flow velocity v of the air outlet_omax；

v_jmax＝v_omax/μ

v_jmax-the maximum static pressure velocity of the outlet, m/s;

mu-flow coefficient of the air outlet;

P_jmax＝ρv_jmax ²/2

P_jmax-the maximum static pressure, Pa, of the air outlet;

rho-density of fluid transported in pipeline, kg/m³Air is 1.20kg/m³；

v_0dmax＝v_jmax/tan(α_min)

v_0dmax-maximum dynamic pressure velocity of section 0, m/s;

S_0min＝Q/v_0dmax

S_0minMinimum cross-sectional area of section 0, m²。

7. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein Δ P in the step S6_eminIs calculated byThe method comprises the following steps:

W_r-the width of the flexible connecting duct, m;

H_r-height of the flexible connecting duct, m;

ΔP_ry＝R_r×L_r

ΔP_ryThe on-way resistance of the flexible connecting air pipe is Pa/m;

L_r-length of the flexible connecting duct, m;

P_rd＝ρv_r ²/2

P_rd-dynamic pressure, Pa, of the flexible connecting duct;

ΔP_rj＝ε_r×P_rd

ΔP_rj-local resistance, Pa, of the flexible connecting duct;

ΔP_r＝ΔP_ry+ΔP_rj

ΔP_r-the total resistance of the flexible connecting duct, Pa;

v_0dmin＝Q/S_b

v_0dmin-minimum dynamic pressure velocity of section 0, m/s;

P_0dmin＝ρv_0dmin ²/2

P_0dmin-minimum dynamic pressure, Pa, of section 0;

v_jmin＝v_0dmin×tan(α_min)

P_jmin＝ρv_jmin ²/2

P_jmin-minimum static pressure, Pa, of the air outlet;

C_tk＝A₀/A₁

ΔP_0jmin＝ε₀×P_0dmin

ΔP_0jmin-minimum local resistance of section 0, Pa;

ε₀-local drag coefficient of section 0;

P_0qmin＝P_0dmin+ΔP_0jmin+P_jmin

P_0qmin-minimum total pressure of section 0, Pa;

ΔP_emin＝(1+K_min)×(ΔP_r+P_0qmin+ΔP_x)

ΔP_emin-the minimum delivery power, Pa, of the air supply branch;

K_min-the minimum richness of the delivery power of the air supply branch;

ΔP_x-the resistance, Pa, of the other irregular local resistance members.

8. The method for designing the variable-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein the width w of the air outlet in the step S7_oThe calculation method comprises the following steps:

S72, according to the average outflow speed v of the drawn air outlet_oCalculating the total area f of the air outlet_o；

f_o＝Q/v_o

f_oTotal area of the outlet, m²；

v_o-drawing up the average outflow speed of the air outlet in m/s;

s73, drawing up the length l of the air outlet_o；

w_o＝f_o/l_o

w_oWidth of the outlet, m.

9. The method for designing the variable cross-section uniform air supply pipeline of the rail transit vehicle as claimed in claim 1, wherein the cross-sectional area S of each cross-section of the variable cross-section air supply pipeline in the step S8_iHeight H_iWidth W_iThe ratio of change k in the height of the cross section of each pipe section_H[(i-(i+1)]And the variation ratio k of the cross-sectional width_W[(i-(i+1)]And air supply branch pipeRoad transport power Δ P_eThe calculation method comprises the following steps:

Q_m-0＝Q_m/Q_0-1

Q_m-0-relative flow at the outlet of the pipe section 0-1;

Q_0-1air volume of pipe section 0-1, m³/s；

v_j＝v_o/μ

v_j-the static pressure velocity of the outlet, m/s;

mu is the outflow coefficient of the air outlet;

v_o-drawing up the outflow speed of the air outlet in m/s;

P_j＝ρv_j ²/2

P_j-static pressure, Pa, of the outlet;

v_0d＝v_j/tanα

v_0d-dynamic pressure velocity of section 0, m/s;

alpha-drawing up an outflow angle alpha of the air outlet;

s808, dynamic pressure velocity v according to section 0_0dSum flow rate Q₀Calculating the sectional area S of the section 0₀Judgment S₀And S_bRelative size of (a);

S₀＝Q₀/v_0d

S₀section area of section 0, m²；

s809, drawing up the height H of the section 0₀；

W₀＝S₀/H₀

W₀The width of section 0, m;

S₀area of cross-section 0, m²；

H₀Height of section 0, m;

P_0d＝ρv_0d ²/2

P_0d-dynamic pressure, Pa, of section 0;

C_tk＝A₀/A₁

S813, according to the sudden expansion ratio C of the inlet (soft connection outlet) of the section 0_tkChecking the sudden local resistance system epsilon of the section 0₀Counting;

P_0j＝ε₀×P_0d

P_0j-sudden local resistance, Pa, of section 0;

ε₀-sudden expansion local drag coefficient of section 0;

P_0q＝P_j+P_0d+P_0j

P_0q-full pressure, Pa, of section 0;

ΔP_e＝(1+K)×(ΔP_r+P_0q+ΔP_x)

ΔP_ethe conveying power Pa of the air supply branch;

k is the richness of the power transmitted by the air supply branch;

ΔP_x-the resistance, Pa, of the other irregular local resistance members;

D₀Flow equivalent diameter, m, of section 0;

W₀width of section 0, m;

H₀height of section 0, m;

S821, according to the specific friction resistance R of the pipe section 0-1_(0-1)And length L_mCalculating the on-way resistance delta P of the pipe section 0-1_(0-1)y；

ΔP_(0-1)y＝R_(0-1)×L_m

ΔP_(0-1)y-on-way resistance, Pa, of the pipe section 0-1;

R_(0-1)-specific friction resistance of pipe section 0-1, Pa/m;

ΔP_(0-1)j＝ε_(0-1)×P_0d

ΔP_(0-1)j-local resistance, Pa, of the pipe section 0-1;

ε_(0-1)-local drag coefficient of pipe section 0-1;

P_1q＝P_0q-(ΔP_(0-1)y+ΔP_(0-1)j)

P_1q-full pressure, Pa, of section 1;

P_1d＝P_1q-P_j

P_1d-dynamic pressure, Pa, of section 1;

v_1d-dynamic pressure velocity of section 1, m/s;

S₁＝Q₁/v_1d

S₁Section area of section 1, m²；

S828, drawing up the height H of the section 1₁；

S829, cross-sectional area S according to section 1₁And defining a height H₁Calculating the width W of the cross section 1₁；

W₁＝S₁/H₁

H₁Height of section 1, m;

W₁width of section 1, m;

k_H(0-1)＝H_1/H₀

k_H(0-1)-the ratio of the variation of the section height of the pipe section 0-1;

k_W(0-1)＝W_1/W₀

k_W(0-1)-the ratio of variation of the section width of the pipe section 0-1;

H_i＝H_(i-1)×k_H[(i-1)-i]

W_i＝W_(i-1)×k_W[(i-1)-i]

H_i-height of section i, m;

W_ithe width of the section i, m;