室内真空排污系统空化影响因素研究

Gas-Liquid-Solid Three Phase Flow in Cesspipe of Vacuum Toilet:A Simulation Study

为了研究不同的含气率和压强对室内真空排污系统管内的空化影响,采用流体仿真软件FLUENT对真空界面球阀在不同含气率和压强下进行数值模拟,基于多相流和流体力学的理论,完成真空管内气液两相流的数值模拟,得到流场内液态水空化后气体含量以及对污物的输送性能影响。将所得的数据进行数据的比较,找到最满足室内真空排泄系统的最佳含气率和压强。结果表明:改变管内的压强,空化现象不明显;随着含气率的增加,液相中逐渐加入气相,气相对液相的作用越强,空化作用得到了加强。空化现象在含气率40%-45%明显,在提高含气率空化反而减弱。将所模拟的结果在室内真空排泄系统设备内进行实验验证,结果与模拟数据相一致。

The gas-liquid-solid three-phase flow in the cess-pipe of vacuum toilet was empirically approximated,mathematically formulated in standard k-εturbulence model,theoretically analyzed,numerically simulated with FLUENT software and experimentally evaluated.The influence of the air volume-fraction and outlet pressure on cavitation of the simplified gas-liquid two-phase flow was investigated.The simulated results show that the air volume-fraction has a major impact.For example,as the air-content increases,the cavitation changes in an increase-decrease mode,maximizing at an air-content in 40%~45%range,possibly because of air-entrainment effect on cavitation alleviation;whereas an increase of the outlet pressure weakly affects the cavitation because a higher induced velocity markedly alleviate cavitation.The simulated and measured results were found to be in good agreement.We suggest that the optimized conditions may include an air-content of 45%and an outlet pressure of 65 kPa.