Rapid evaluation method for hydraulic friction resistance of pipelines

A technology of hydraulic friction resistance and evaluation method, which is applied in special data processing applications, instruments, electrical digital data processing, etc. The effect of improving engineering quality, measurement and calculation convenience

Inactive Publication Date: 2017-05-31
CHINA INST OF WATER RESOURCES & HYDROPOWER RES
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Equivalent roughness in Korotkoff formula k It comprehensively reflects the influence of coarse particles on the inner wall of the pipeline and various factors on the loss along the pipeline. The fluid test has been used to measure the pipeline loss along the pipeline at high Reynolds numbers, and the hydraulic friction coefficient lambda Converted to the rough grain height of the Nicholas rough pipe with the same diameter, it is considered that the rough grain height is close to the average size of the irregular rough microelements on the inner wall of the pipe, which is the equivalent roughness k , but the fluid test requires a fixed test site and test platform, and consumes a lot of time and cost, so it is not suitable for the test of large-diameter pipelines

Method used

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  • Rapid evaluation method for hydraulic friction resistance of pipelines
  • Rapid evaluation method for hydraulic friction resistance of pipelines
  • Rapid evaluation method for hydraulic friction resistance of pipelines

Examples

Experimental program
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Effect test

Embodiment 1

[0046] This embodiment is a rapid evaluation method for pipeline hydraulic friction. The basic idea of ​​the method is to introduce the (machined) surface roughness in machining into the detection of the inner wall surface of the water conservancy pipeline as the hydraulic friction coefficient of the pipeline k use.

[0047] The existing method is based on R q The values ​​represent equivalent roughness values ​​and give k ≈5 R q , k ≈3 R q , k ≈1.6 R q and other calculation methods.

[0048] In this example, the maximum height value of the roughness profile is used R z ,Make R z ≈ k . Table 1 gives R a , R z , R q The experimental results are compared. It can be seen from the 1-5 sets of data in the table that, R z ≈ k , with 5 R q compared to, R z value closer to k value, and R z The definition and equivalent roughness k The physical meaning of is closer, and it can better represent the influence of the roughness of the inner wall of the pi...

Embodiment 2

[0087] This embodiment is an improvement of the first embodiment, and it is about the sampling length of the first embodiment lr or measure length ln Corresponding R a and R z refinement of the range. The sampling length described in this example lr or measure length ln Corresponding R a and R z The ranges are as follows:

[0088] R a ≤10 microns, lr 2.5mm, ln 12.5 mm; 10 microns R a ≤80 microns, lr 8mm, ln is 40mm;

[0089] R z ≤50 microns, lr 2.5mm, ln 12.5 mm; 50 microns R z ≤200 microns, lr 8mm, ln is 40mm.

[0090] Expressed in form as:

[0091] Table 2 R a Roughness sample length of value

[0092]

[0093] table 3 R z Roughness sample length of value

[0094]

[0095] Table 4 and Table 5 are the specifications of machining surface roughness, and the roughness sampling length recommended in the Chinese National Standard (GB / T 10610 2009). The selection of sampling length has a great influence on the measurement results of roughness...

Embodiment 3

[0101] This embodiment is an improvement of the above-mentioned embodiment, which is calculated by using the above-mentioned embodiment R a , R z The method for evaluating the quality of the inner wall of the pipeline, the process is shown in image 3 Shown:

[0102] Set after the step of calculating the average value: the step of calculating the standard deviation and the step of judging the quality of the pipeline:

[0103] Steps to calculate standard deviation:

[0104] ,

[0105] ;

[0106] Steps for Judging Pipeline Quality: Used to calculate by formula R a and R z coefficient of dispersion cv Ra , cv Rz :

[0107] ,

[0108] ;

[0109] and judge cv Ra , cv Rz Is it less than the discrete coefficient cv If it is "Yes", it means that the measured pipe is uniform, otherwise it means that the measured pipe fittings are not lined with the same material, or the production quality of some pipe fittings is not up to standard.

[0110] In this ...

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Abstract

The invention relates to a rapid evaluation method for hydraulic friction resistance of pipelines. The rapid evaluation method comprises the steps of preliminary estimating; selecting an evaluation sampling length and an evaluation rated length; evaluation detecting; evaluating whether or not the sampling length is in a proper range; selecting a shorter sampling length; determining the sampling length; regular measuring; calculating the average value; calculating a coefficient of the hydraulic friction resistance. According to the method, a measuring instrument for surface roughness in existing machining is used for repeatedly adjusting measuring length, and the maximum height of a surface roughness profile (i)R( / i)(i)z( / i) can be used as an equivalent roughness (i)k( / i), which is taken into Colebrook - White equation to calculate the coefficient of the hydraulic friction resistance (i) lambda ( / i). The rapid evaluation method for the hydraulic friction resistance of pipes makes the measurement and calculation of the coefficient of the hydraulic friction resistance more convenient, faster, and simpler, improves the quality of pipeline construction, and reduces the operation cost of pipeline projects.

Description

technical field [0001] The invention relates to a rapid evaluation method for pipeline hydraulic friction, which is a method for evaluating hydraulic parameters and a method for evaluating internal friction of hydraulic pipelines. Background technique [0002] Pipeline hydraulic friction coefficient is one of the important technical parameters of fluid transportation engineering design, and the result of its value directly affects the accuracy of hydraulic calculation results. The accurate measurement and reasonable value of the hydraulic friction coefficient are very important for the overall layout, design scale, equipment selection, operation management, energy saving and reduction of pipeline projects such as long-distance water supply projects, urban water supply and drainage projects, agricultural irrigation projects, and oil transportation row is of great significance. [0003] The hydraulic calculation formula commonly used in engineering is the Darcy-Weisbach (Darc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50
CPCG06F30/20G06F2119/06
Inventor 刘之平郭永鑫杨开林郭新蕾付辉李甲振王涛夏庆福
Owner CHINA INST OF WATER RESOURCES & HYDROPOWER RES
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