Quick filling vertical pipeline simulation method considering intercepted air energy dissipation

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...

AI Technical Summary

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

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