CN111143954A - Manufacturing method of branched water pipe capable of effectively reducing local head loss - Google Patents
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Abstract
A manufacturing method of a branched water pipe capable of effectively reducing local head loss sequentially adopts a design model for constructing a branched structure of a water pipe network; calculating the structural parameters of the water pipe network bifurcation structure; defining the coverage area of a water delivery pipe network, planning the arrangement scheme of the water delivery pipe, and collecting flow data in the water delivery pipe; and guiding and designing the water pipe network bifurcation structures with different requirements by using the structural parameters according to the flow data in the water pipe. The invention obtains the structural parameters by establishing a design model of the bifurcation structure and calculating, thereby obtaining the bifurcation structure of the water pipe network, which can reduce the local head loss.
Description
Technical Field
The invention belongs to the field of design optimization of water pipes, and particularly relates to a manufacturing method of a forked water pipe capable of effectively reducing local head loss.
Background
In water delivery engineering, a bifurcation structure is often used to achieve the purpose of diversion so as to meet the requirements of multiple water supplies. According to engineering experience, after water flow passes through the bifurcation structure, local hydraulic loss is caused by changes of flow speed and direction; if a small bifurcation angle is used, the structure is not favorable for the water flow, and the bifurcation structure is difficult to manufacture due to an excessively small included angle. At present, aiming at the design defect that the bifurcation structure can not meet the hydraulic requirement and the structural requirement at the same time, a scientific calculation method is still lacked in the design specification, the specification generally suggests that the bifurcation angle of the traditional bifurcation structure is 90 degrees, the bifurcation angle of the branch pipe of the hydropower station is preferably 45-60 degrees according to the engineering experience, and the like. In addition, the water flow of the branch pipe after the flow division is obviously reduced, and the pipe diameter of the branch pipe is rarely and reasonably optimized in the specification or practical application, so that the water flow speed is reduced, and the hydraulic loss is caused.
If the optimal design method for the bifurcation structure of the water delivery pipe network can be provided, the reasonable range of the bifurcation angle and the relative value of the main pipe radius and the branch pipe radius are optimized, the effect of reducing the local head loss is achieved, the improvement of the water delivery efficiency is facilitated, and the engineering cost is reduced.
Disclosure of Invention
In view of the technical problems in the background art, the method for manufacturing the branched water pipe capable of effectively reducing the local head loss provided by the invention calculates the structural parameters of the branched water pipe by establishing a design model of the branched structure, so as to obtain the branched structure of the water pipe network capable of reducing the local head loss.
In order to solve the technical problems, the invention adopts the following technical scheme to realize:
a method for manufacturing a branched water pipe capable of effectively reducing local head loss comprises the following steps:
1) constructing a design model of a water pipe network bifurcation structure;
2) calculating the structural parameters of the water pipe network bifurcation structure;
3) defining the coverage area of a water delivery pipe network, planning the arrangement scheme of the water delivery pipe, and collecting flow data in the water delivery pipe;
4) and guiding and designing the water pipe network bifurcation structures with different requirements by using the structural parameters according to the flow data in the water pipe.
In a preferred embodiment, in step 1), before the model construction, an assumption is first made about the branching structure of the water pipe network, where the assumption mainly includes:
assuming that a bifurcation structure divides the water conveying pipe into two parts at a bifurcation node and distributes the two parts equally, and the two branch water pipes are symmetrically positioned on the same plane;
assume two, that the head loss of water flow on the pipe wall increases with the increase of the internal area and volume of the pipe wall; the thickness of the pipe is approximately proportional to the radius of the pipe;
assume three, that one follows the principle of head loss minimization in pipe and branch design.
In a preferred embodiment, when the design model of the water pipe network branching structure is established in step 1), the method comprises the following steps:
1) according to the motion characteristics of fluid in the rigid pipeline, the functional expression of the flow q in the pipeline, the radius r, the length l and the pressure difference delta p of the pipeline is obtained as
Obtaining that the flow q is in direct proportion to the fourth power of the radius r of the pipeline and the pressure difference delta p and in inverse proportion to the length l;
2) according to the second assumption, the water flow is obtained to overcome the head loss caused by cavitation in the pipeline
The internal surface area of the tube can be expressed as S-4 pi rl and the volume of the tube as V-pi (d)2+2rd) l, the head loss of the water flow on the pipe wall can be simplified and expressed as E2＝brαl, wherein b is a proportionality coefficient, and the value range of α is 1- α -2;
3) finally, the function relation of the total head loss of the bifurcation structure, the radius of the main pipeline, the radius of the branch pipeline and the bifurcation angle is obtained as E ═ kq (kq)2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1。
In a preferred embodiment, the drawing of the structure diagram of the branched water pipe yields a formula of L ═ L-H/tan θ, L1H/sin θ, and substituting the formula into E ═ kq2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1In the function expression;
thus, the function expression of the optimal design model is obtained as follows:
E(r,r1,θ)＝(kq2/r4+br4)(L-H/tanθ)+(kq1 2/r1 4+br1 4)2H/sinθ。
in a preferred embodiment, when calculating the structural parameter of the branched structure in step 2), the calculation process is to take the minimum total head loss as a target: firstly, making the partial derivative of the total water head loss to the radius of a main pipeline be 0; the partial derivative of the total head loss to the radius of the branch pipeline is 0; the partial derivative of the total head loss to the bifurcation angle is 0, and a differential equation set is established, namely
Then calculate to obtain
Instant game
The lambda is more than or equal to 1.26 and less than or equal to 1.32, and theta is more than or equal to 37 degrees and less than or equal to 49 degrees are obtained.
In a preferred scheme, in the step 3), area division is carried out according to the coverage area of the water conveying pipe network, the total quantity of the area water demand is measured, and a corresponding branch pipe radius r is designed1The value of the main pipe radius r can be obtained according to the value of λ, and the bifurcation angle θ is within the above range.
In a preferred scheme, the step 4) adopts branch structures with different specifications and branch modes as required; the bifurcation mode mainly comprises the following two modes:
1) the first water delivery pipe network bifurcation structure is in a Y-shaped bifurcation mode and consists of a main pipeline and two symmetrical branch pipelines with the same pipe diameter, and the bifurcation mode has the advantages of symmetrical and uniform water flow distribution;
2) the bifurcation mode of the bifurcation structure of the second water delivery pipe network is a halberd bifurcation mode, namely, the bifurcation angle of any one of the two branch pipes is changed into 0, so that the branch pipe and the main pipe are kept consistent, and the bifurcation mode has the advantage that bifurcation sections are short when bifurcation nodes are more.
This patent can reach following beneficial effect:
the invention designs the optimal design method and the structural design parameters of the water pipe network bifurcation structure, which can effectively reduce the local head loss, and adjusts the relative values of the bifurcation angle of the water pipe network bifurcation structure, the main pipe radius and the main pipe radius according to the structural design parameters, thereby being beneficial to reducing subjective experience errors during the design.
The invention can effectively reduce the local head loss, improve the water delivery efficiency and reduce the hydraulic erosion harm. Compared with the traditional bifurcation structure, the invention provides the optimized range of the ratio of the bifurcation angle to the pipeline radius, improves the utilization rate of the branch water pipeline, reduces the diameter of the branch pipe, reduces the use amount of the pipe and lowers the engineering cost.
The bifurcation structure can be applied to various water delivery projects, such as optimization of a branch pipe of a hydropower station, a bifurcation structure of an urban water supply pipeline, a water supply network for irrigation and water conservancy in a farmland and the like.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
FIG. 1 is a design model of a water pipe network bifurcation structure according to the present invention;
FIG. 2 shows a Y-branch pattern according to the present invention;
FIG. 3 shows a Bu-type bifurcation method according to the present invention.
In the figure: main pipe radius r, branch pipe radius r1Main pipe length l, branch pipe length l1The included angle theta between the main pipe and the branch pipe axis, the main pipe flow q and the branch pipe flow q1The distance H between the central axis of the branch pipe and the central axis of the main pipe, and the total length L of the bifurcation structure.
Detailed Description
A preferred scheme is as shown in fig. 1 to 3, a method for manufacturing a bifurcated water pipe capable of effectively reducing local head loss, when designing and applying a bifurcated structure to connect a water pipe, comprises the following steps:
before model construction, firstly, an assumption is made on a water pipe network branching structure, and the assumption mainly comprises the following steps:
assuming that a bifurcation structure divides the water conveying pipe into two parts at a bifurcation node and distributes the two parts equally, and the two branch water pipes are symmetrically positioned on the same plane;
assume two, that the head loss of water flow on the pipe wall increases with the increase of the internal area and volume of the pipe wall; the thickness of the pipe is approximately proportional to the radius of the pipe;
assume three, that one follows the principle of head loss minimization in pipe and branch design.
Step one, constructing a design model of a water pipe network bifurcation structure;
when a design model of a water pipe network branched structure is established, the design model is carried out according to the following steps, and a simplified model diagram is shown in fig. 1:
① according to the motion characteristics of fluid in rigid pipe, the functional expression of flow q in pipe, radius r, length l and pressure difference Δ p is obtained
Obtaining that the flow q is in direct proportion to the fourth power of the radius r of the pipeline and the pressure difference delta p and in inverse proportion to the length l;
② according to the second assumption, the water flow is obtained to overcome the head loss caused by cavitation in the pipeline
The internal surface area of the tube can be expressed as S-4 pi rl and the volume of the tube as V-pi (d)2+2rd) l, the head loss of the water flow on the pipe wall can be simplified and expressed as E2＝brαl, wherein b is a proportionality coefficient, and the value range of α is 1- α -2;
③, obtaining the function relationship of total head loss of the bifurcation structure and the radius of the main pipeline, the radius of the branch pipeline and the bifurcation angle as E ═ kq (kq)2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1。
Further, a structure of the branched water pipe is drawn, and as can be seen from fig. 1, L ═ L-H/tan θ, L1H/sin θ, and substituting the formula into E ═ kq2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1In the function expression;
thus, the function expression of the optimal design model is obtained as follows:
E(r,r1,θ)＝(kq2/r4+br4)(L-H/tanθ)+(kq1 2/r1 4+br1 4)2H/sinθ。
step two, calculating the structural parameters of the water pipe network bifurcation structure;
when the structural parameter of the bifurcation structure is calculated, the minimum total head loss is taken as a target, and the specific calculation process is as follows: firstly, making the partial derivative of the total water head loss to the radius of a main pipeline be 0; the partial derivative of the total head loss to the radius of the branch pipeline is 0; the partial derivative of the total head loss to the bifurcation angle is 0, and a differential equation set is established, namely
Then calculate to obtain
Instant game
The lambda is more than or equal to 1.26 and less than or equal to 1.32, and theta is more than or equal to 37 degrees and less than or equal to 49 degrees are obtained.
Step three, defining the coverage area of the water delivery pipe network, planning the arrangement scheme of the water delivery pipe, and collecting flow data in the water delivery pipe;
the method specifically comprises the following steps: in the step 3), area division is carried out according to the coverage area of the water delivery pipe network, the total quantity of the area water demand is measured, and the corresponding branch pipe radius r is designed1The value of the main pipe radius r can be obtained according to the value of λ, and the bifurcation angle θ is within the above range.
And step four, guiding and designing the water pipe network bifurcation structures with different requirements by using the structural parameters according to the flow data in the water pipe.
The method specifically comprises the following steps: the method comprises the following steps of adopting bifurcation structures with different specifications and bifurcation modes according to requirements; the bifurcation mode mainly comprises the following two modes:
① the first water delivery pipe network bifurcation structure has Y-shaped bifurcation mode, and comprises a main pipe and two symmetrical branch pipes with the same pipe diameter, and the bifurcation mode has the advantages of symmetrical and uniform water flow distribution;
② the second water pipe network branching structure has a branching mode of Bu type, that is, the branching angle of any one of the two branch pipes is changed to 0, so that the branch pipe and the main pipe are consistent.
The structural parameters of the water pipe network bifurcation structure obtained by the optimization method can effectively reduce the water head loss, and in practical application, the bifurcation angle of the water pipe network bifurcation structure is generally 90 degrees, theta of the hydropower station bifurcation is generally equal to or more than 45 degrees and equal to or less than 60 degrees according to experience, and theta of the bifurcation structure after optimization is equal to or more than 37 degrees and equal to or less than 49 degrees.
From the above model E (r, r)1,θ)＝(kq2/r4+br4)(L-H/tanθ)+(kq1 2/r1 4+br1 4)2H/sin θ shows that:
the bifurcation angle has a certain influence on the head loss, and it can be calculated that E is 0.34 when θ is 37 °, E is 0.41 when θ is 45 °, E is 0.47 when θ is 49 °, E is 0.58 when θ is 60 °, and E is 1 when θ is 90 °, it can be seen that the head loss is larger as the bifurcation angle is larger, and a bifurcation structure having a bifurcation angle of 90 ° is obtained, and the optimized bifurcation structure head loss reduction rate is 53% or more and β or less and 66%, wherein
The reasonable range of the relative values of the main pipe radius and the branch pipe radius and the bifurcation angle obtained by optimizing the model makes up the defect that the bifurcation angle of the bifurcation pipe is selected according to engineering experience in the design specification of the pressure steel pipe of the hydropower station, can provide reference for the aspect of structural design, and is favorable for improving the reasonability of the structure.
Claims (7)
1. A method for manufacturing a branched water pipe capable of effectively reducing local head loss is characterized by comprising the following steps:
1) constructing a design model of a water pipe network bifurcation structure;
2) calculating the structural parameters of the water pipe network bifurcation structure;
3) defining the coverage area of a water delivery pipe network, planning the arrangement scheme of the water delivery pipe, and collecting flow data in the water delivery pipe;
4) and guiding and designing the water pipe network bifurcation structures with different requirements by using the structural parameters according to the flow data in the water pipe.
2. The method for manufacturing the branched water delivery pipe capable of effectively reducing the local head loss according to claim 1, is characterized in that: in step 1), before model construction, an assumption is first made on a water pipe network branching structure, and the assumption mainly includes:
assuming that a bifurcation structure divides the water conveying pipe into two parts at a bifurcation node and distributes the two parts equally, and the two branch water pipes are symmetrically positioned on the same plane;
assume two, that the head loss of water flow on the pipe wall increases with the increase of the internal area and volume of the pipe wall; the thickness of the pipe is approximately proportional to the radius of the pipe;
assume three, that one follows the principle of head loss minimization in pipe and branch design.
3. The method for manufacturing the branched water delivery pipe capable of effectively reducing the local head loss according to claim 2, is characterized in that: when the design model of the water pipe network bifurcation structure is established in the step 1), the design method comprises the following steps:
1) according to the motion characteristics of fluid in the rigid pipeline, the functional expression of the flow q in the pipeline, the radius r, the length l and the pressure difference delta p of the pipeline is obtained as
Obtaining that the flow q is in direct proportion to the fourth power of the radius r of the pipeline and the pressure difference delta p and in inverse proportion to the length l;
2) according to the second assumption, the water flow is obtained to overcome the head loss caused by cavitation in the pipeline
The internal surface area of the tube can be expressed as S-4 pi rl and the volume of the tube as V-pi (d)2+2rd) l, the head loss of the water flow on the pipe wall can be simplified and expressed as E2＝brαl, wherein b is a proportionality coefficient, and the value range of α is 1- α -2;
3) finally, the function relation of the total head loss of the bifurcation structure, the radius of the main pipeline, the radius of the branch pipeline and the bifurcation angle is obtained as E ═ kq (kq)2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1。
4. The method for manufacturing the branched water delivery pipe capable of effectively reducing the local head loss according to claim 3, is characterized in that: drawing a structure diagram of the branched water pipe to obtain a formula L which is L-H/tan theta, L1H/sin θ, and substituting the formula into E ═ kq2/r4+br4)l+(kq1 2/r1 4+br1 4)2l1In the function expression;
thus, the function expression of the optimal design model is obtained as follows:
E(r,r1,θ)＝(kq2/r4+br4)(L-H/tanθ)+(kq1 2/r1 4+br1 4)2H/sinθ。
5. the method for manufacturing the branched water delivery pipe capable of effectively reducing the local head loss according to claim 1, is characterized in that: in the step 2), when calculating the structural parameters of the bifurcation structure, the method aims at the minimum total head loss, and comprises the following specific calculation processes: firstly, making the partial derivative of the total water head loss to the radius of a main pipeline be 0; the partial derivative of the total head loss to the radius of the branch pipeline is 0; the partial derivative of the total head loss to the bifurcation angle is 0, and a differential equation set is established, namely
Then calculate to obtain
Instant game
The lambda is more than or equal to 1.26 and less than or equal to 1.32, and theta is more than or equal to 37 degrees and less than or equal to 49 degrees are obtained.
6. According to the claimsSolving 1 the manufacturing method of the branched water pipe capable of effectively reducing the local head loss is characterized in that: in the step 3), area division is carried out according to the coverage area of the water delivery pipe network, the total quantity of the area water demand is measured, and the corresponding branch pipe radius r is designed1The value of the main pipe radius r can be obtained according to the value of λ, and the bifurcation angle θ is within the above range.
7. The method for manufacturing the branched water delivery pipe capable of effectively reducing the local head loss according to claim 1, is characterized in that: step 4), adopting bifurcation structures with different specifications and bifurcation modes according to requirements; the bifurcation mode mainly comprises the following two modes:
1) the first water delivery pipe network bifurcation structure is in a Y-shaped bifurcation mode and consists of a main pipeline and two symmetrical branch pipelines with the same pipe diameter, and the bifurcation mode has the advantages of symmetrical and uniform water flow distribution;
2) the bifurcation mode of the bifurcation structure of the second water delivery pipe network is a halberd bifurcation mode, namely, the bifurcation angle of any one of the two branch pipes is changed into 0, so that the branch pipe and the main pipe are kept consistent, and the bifurcation mode has the advantage that bifurcation sections are short when bifurcation nodes are more.
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Cited By (3)
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| CN112594470A (en) * | 2020-12-16 | 2021-04-02 | 中国电建集团昆明勘测设计研究院有限公司 | Method for arranging crescent rib bifurcated pipe stiffening beam |
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| GB2598488A (en) * | 2020-06-18 | 2022-03-02 | China Three Gorges Corp | Method for calculating head loss coefficient and branch pipe flow distribution of multi-point water intake |
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