Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Calculation method of transient pressure of trapped air mass in pipe impinged by water flow

A technology of water impact and calculation method, applied in calculation, computer-aided design, design optimization/simulation, etc., can solve problems such as model deviation, imperfection, difficulty, etc., to ensure safe operation of the project, reduce project cost, and optimize the project The effect of the design

Active Publication Date: 2019-07-02
XINJIANG AGRI UNIV
View PDF4 Cites 0 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Affected by the incomplete similarity theory and similarity criterion of transient flow models, it is difficult to obtain reliable transient pressure values ​​of prototype pipelines through experimental research methods
In terms of numerical calculation methods, researchers ignore the elasticity of water and pipe walls and analyze according to rigid theory, and establish a one-dimensional rigid mathematical model; consider the elasticity of water body and pipeline, and establish a one-dimensional elastic water model, rigid plug, virtual plug, etc. Elastic mathematical models, but these equations themselves cannot directly obtain analytical solutions, only approximate solutions can be obtained by numerical integration, which involves complex graphic methods and programming, and it is difficult for engineers and technicians to use this method to calculate and predict pipeline internal transients. Transient pressure peaks that may be generated by variable flow and pressure variation with time
In addition, the study found that both rigid and elastic models have large deviations when the trapped air mass in the pipeline is small
Based on the above reasons, some researchers have also carried out the research on the approximate analytical solution of the maximum pressure of the water flow impacting the air mass, but the analytical solution expression of the maximum pressure generated by the impacting air mass and the oscillation period given by the researchers contains an unknown functional relationship, resulting in the air mass The maximum pressure and period cannot be directly calculated, and engineers and technicians cannot directly apply the formula to actual engineering

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Calculation method of transient pressure of trapped air mass in pipe impinged by water flow
  • Calculation method of transient pressure of trapped air mass in pipe impinged by water flow
  • Calculation method of transient pressure of trapped air mass in pipe impinged by water flow

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0032] Embodiment: this embodiment is applied to figure 1 Calculation of the transient pressure of the trapped air mass impacted by the water flow in the pressurized pipeline shown. figure 1 Medium, the length of the pressurized water pipeline L =10m, pipe diameter D =35mm, pipe inlet pressure p 0 =304 kPa, the end of the pipe is closed, no gas leakage, the length of the initially retained air bag L a0 = 5m, X= 2.5m, k = 1.4, p a = 98kPa. Substituting these data into formula (8), the pressure transient process produced when the water flow hits the air mass is calculated. The calculated results and the measured data are simultaneously plotted on the figure 2 middle.

[0033] (8)

[0034] Depend on figure 2 It can be seen that the relative errors of the calculated value and the measured value of the formula (8) with respect to the peak pressure, the moment when the peak pressure appears, and the oscillation period of the pressure over time are 2.5%, 13% an...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention provides a method for calculate transient pressure of retained air mass in pipeline impinge by water flow. The equations of motion of water column and the instantaneous equations of gaspressure are established by taking the horizontal pressurized transmission / drainage pipeline with retained air mass as the center. The second-order nonlinear differential equations are obtained by simultaneous equations with the transient flow pressure of pipeline as the strain value and the instantaneous displacement of water column as the independent variable. The equation is subjected to linearization so as to obtain the calculation formula of air-water transient pressure of retained air mass in pipeline impinge by water flow, which takes into account the effects of time, local atmosphericpressure, gas state index, water flow density, inlet pressure, pipe length, and retained air mass length. The invention provides a tool for calculation of the peak value of air-water hammer pressure and oscillation period produced by the transient flow phenomenon that the water flow impinges on a retained air mass in a pressurized pipe, and provides theoretical basis for optimizing the engineeringdesign of the pressurized transmission / drainage pipeline, reducing the engineering cost and ensuring the safe operation of the engineering calculation.

Description

technical field [0001] The invention relates to the calculation of the water-gas transient flow process of a pressure transmission / drainage pipeline system, and belongs to the technical field of numerical calculation of air-water hammer pressure generated by a pressure transmission / drainage pipeline. Background technique [0002] In the pressurized water pipeline system, there is trapped air mass due to poor exhaust in some high-convex parts or closed ends of the pipeline. The gas-water hammer pressure generated by the variable flow phenomenon will be much greater than the general water hammer pressure, which is the main reason for the pipe burst. [0003] It has been one of the important subjects in the study of transient flow to solve the transient flow pressure generated by the water flow impacting the air mass in the water pipeline. At present, experimental research and numerical calculation models are mainly used for measurement and calculation analysis. [0004] Affe...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50
CPCG06F30/20G06F2113/14G06F2119/06
Inventor 李琳石铁玉靳晟张小莹谭义海
Owner XINJIANG AGRI UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com