Flow characteristics of roots pumps operating with gas-liquid mixtures

The research article 'Numerical Investigation and Performance Enhancement of Roots Pumps Operating with Gas-Liquid Mixtures' has been published in Elsevier journal Vacuum.

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.

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