Experimental Investigation and Numerical Validation of a Roots Pump’s Performance Operating with Gas-Liquid Mixtures

To facilitate the high operating pressure of a novel underwater power cycle, the potential of Roots pumps for pressurizing gas-liquid mixtures is experimentally investigated in this paper. The experimental facility is constructed, and the effects of inlet gas volume fractions and rotational speeds on the pump performance are discussed. The results show that the increased inlet gas volume fraction is beneficial to increasing the pump efficiency. This is associated with the increased pressure ratio and the gas-liquid mixture compressibility. In addition, the increases in rotational speed and liquid phase volume fraction negatively affect the pump’s efficiency. These phenomena are caused by the resulting high pressure difference and subsequently the back-flow from the pump outlet, thereby increasing the gap leakage and decreasing the Roots pump’s operating efficiency. The numerical model is further compared against experimental resultsk and the maximum difference is found to be less than 7.53%. This paper experimentally tests the potential of Roots pumps for pressurizing gas-liquid mixtures.