Quick filling vertical pipeline simulation method considering intercepted air energy dissipation

A technology of trapping air and dissipating energy, applied in CAD numerical modeling, instrumentation, design optimization/simulation, etc., can solve the problem of not considering the heat transfer energy loss of trapped cavitation, unable to explain the phenomenon of white fog and heat pipe wall, underestimating Problems such as pressure decay rate to achieve the effect of solving transient simulation problems

Pending Publication Date: 2022-04-29
HOHAI UNIV
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Problems solved by technology

This method suffers from the following drawbacks: 1) it underestimates the pressure decay rates, although they are usually a good predictor of the first cycle - the air compression-expansion cycle; White mist and heat pipe wall phenomenon; 3) Heat transfer of trapped air pockets and energy loss due to severe air-water interaction are not considered
These facts imply that, during the rapid filling process, both heat transfer from trapped air pockets and vigorous air-water interactions lead to important energy losses, factors that are rarely considered in existing 1D models

Method used

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  • Quick filling vertical pipeline simulation method considering intercepted air energy dissipation
  • Quick filling vertical pipeline simulation method considering intercepted air energy dissipation
  • Quick filling vertical pipeline simulation method considering intercepted air energy dissipation

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0120] The experimental data measured in a vertical pipeline with a clear air-water interface in the pipeline hydraulic transient experimental device system designed and built by Zhou in 2018 is selected to verify the effectiveness of the method for simulating the pressure oscillation in a fast-filling pipeline with an interception airbag.

[0121] In this embodiment, the upstream pressure vessel (relative pressure Pr) is connected to an 8.862m long, 4cm inner diameter pipe at the end, which is composed of an 8.382m long horizontal pipe and a 0.48m long terminal vertical pipe. At first, the control valve is completely closed, and the trapped air pocket La0 is at atmospheric pressure, and the valve opens instantly.

[0122] Comparing the simulation results of the method of the present invention with the above simulation results, we can get the results as follows Figure 4 The pressure curve shown by Figure 4 It can be seen that the heat transfer model considering steady friction, un...

Embodiment 2

[0124] The simulation results of the model with traditional empirical multi-party relationship are selected to verify the effectiveness of the new heat transfer model to simulate energy dissipation.

[0125] In this example, the constant polytropic index m of adiabatic process (without heat transfer) is m＝1.4, and TVB turbulence model is used to simulate the unsteady friction.

[0126] Comparing the simulation results of the method of the present invention with the above simulation results, we can get the results as follows Figure 5 The pressure curve shown by Figure 5 It can be seen that the heat transfer model provided by the invention can accurately simulate the energy dissipation of the system; However, the empirical multi-party relationship method with adiabatic hypothesis can only accurately reproduce the pressure and temperature during the first two oscillations of the system test, and with the rapid filling event advancing, the oscillation peak value and time will be great...

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Abstract

The invention discloses a rapid vertical pipeline filling simulation method considering trapped air energy dissipation. The method comprises the steps that a continuity equation and a pressure balance equation of a moving air-water interface are established; constructing a heat transfer model by taking a water hammer theory as a basis and combining a heat transfer principle of a closed air bag and an equation of ideal gas; a first-order local MOC interpolation interface tracking method is adopted to solve the filling water column control equation and the air heat transfer equation considering the unsteady friction, and the air pressure, the speed and the position of the moving air-water interface are obtained through calculation; solving by using a Runge-Kutta four-order numerical integration method; and performing simulation according to the solving result to obtain a simulation result. The heat transfer model considering trapped air energy dissipation is researched, rime fog and heat pipe wall phenomena of related experiments can be explained, the accuracy problem of a traditional model is solved, and the method has important significance on heat transfer of trapped air pockets in actual rapid filling vertical pipelines and energy consumption simulation of violent air-water interaction.

Description

Technical field [0001] The invention belongs to the technical field of hydraulic numerical simulation calculation of hydropower stations (pumping stations), and in particular relates to a simulation method of fast filling vertical pipelines considering the energy dissipation of trapped air. technical background [0002] Trapped air pockets in pressurized water supply and urban sewer systems may cause serious operational challenges, and may even lead to the formation of geysers or damage to system components. Recently, a series of experiments have been conducted to carefully study the interaction between fluid transients and air pockets, such as the dynamic behavior of online and offline air pockets in horizontal pipelines, the transient pressure caused by confined air pockets and air discharge during rapid filling, and the dynamic mechanism and air-water interaction during geysers. These latest studies further reveal the danger and complexity of transient flow with cavitation. Im...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/28G06F113/08G06F119/08G06F119/14G06F111/10
CPCG06F30/28G06F2113/08G06F2119/14G06F2119/08G06F2111/10
Inventor 周领陆燕清李赟杰胡垠盈方浩宇薛子剑刘德有
Owner HOHAI UNIV
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