Abstract The suitability of Roots pumps operating with gas-liquid mixture is investigated. The computational fluid dynamics method is employed and validated against experimental results. To highlight flow characteristics of Roots pumps operating with gas-liquid mixtures, the Roots pumps operating with pure gas and liquid are included as the reference case. A pump efficiency of 48% is attained for the gas-liquid mixture at the volume ratio of 4:1, while the efficiency of 59% for gas and 80% for liquid are achieved, respectively. The reduced pre-compression effects and the resulting high-pressure difference between the outlet and the working chamber are found to be reason for low efficiency. To enhance performance, increasing the gap between the rotor and casing is utilized. It is demonstrated that the flow efficiency is increased, while the volumetric efficiency cannot be maintained due to the increased leakage through the gap between two rotors. Alternatively, the configuration with the gradually varied gap near the pump outlet is employed. The pump efficiency is significantly enhanced due to increased pre-compression effects, while the high volumetric efficiency can also be maintained. The work provides the insight into flow characteristics of Roots pump operating with gas-liquid mixture.

中文翻译：

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气液混合气罗茨泵数值研究及性能提升

摘要 研究了气液混合气罗茨泵的适用性。采用计算流体动力学方法并根据实验结果进行验证。为了突出使用气液混合物运行的罗茨泵的流动特性，将使用纯气体和液体运行的罗茨泵作为参考案例包括在内。体积比为 4:1 的气液混合物的泵效率为 48%，而气体的效率为 59%，液体的效率分别为 80%。降低的预压缩效果和由此产生的出口和工作腔之间的高压差被认为是低效率的原因。为了提高性能，增加了转子和外壳之间的间隙。结果表明，流动效率提高，而由于两个转子之间的间隙泄漏增加，容积效率无法保持。或者，采用在泵出口附近具有逐渐变化的间隙的构造。由于增加了预压缩效应，泵效率显着提高，同时也可以保持高容积效率。这项工作提供了对使用气液混合物运行的罗茨泵的流动特性的深入了解。