Internal flow field and hydraulic characteristics of two-stage liquid ring compressor
ZHANG Renhui1,2*, LIU Bowen1, GUO Guangqiang1,2, YU Shuainian1, ZHENG Zhi1,2
1. College of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China; 2. Key Laboratory of Fluid Machinery and Systems, Lanzhou University of Technology, Lanzhou, Gansu 730050, China
Abstract：By using a method that combines numerical simulation and testing, the internal flow field and hydraulic performance of a multi-stage liquid ring compressor under different working conditions as well as different impeller width ratios were compared and analyzed on the 2SY-6 two-stage liquid ring compressor. The analysis of the results shows that the blade load of the second-stage impeller is smaller than that of the primary impeller, so the gas-liquid interface at the outlet of the second-stage impeller is smoother than that of the primary impeller. The reflux intensity of the first-stage impeller suction port area is stronger than that of the second-stage impeller suction port area, and the turbulent kinetic energy of the first-stage impeller suction port area is obviously greater than that of the second-stage impeller. In the equal impeller outer diameter design, the compression ratio of the secondary impeller is far less than that of the primary impeller, and the power capacity of the secondary impeller is lower than that of the primary impeller. As the compression ratio of the inlet and outlet for the primary impeller is relatively large and located on the right side of the efficiency maximum point, the efficiency of the first-stage impeller gradually decreases with the increase of the pump compression ratio, while the compression ratio range of the second-stage impeller includes the maximum point, so its efficiency first increases and then decreases. With the increase of the width of the secondary impeller, the suction capacity gradually increases, and the flow rate of each condition also increases. The efficiency under low compression ratio conditions gradually increases with the decrease of the k value, and the efficiency under high compression ratio conditions increases first and then decreases with the decrease of the k value. The compression ratio of primary and secondary impellers increases with the increase of the pump outlet compression ratio. With the decrease of the width ratio of the primary and secondary impellers, the compression ratio curve of the secondary impeller gradually moves upward, while the compression ratio curve of the primary impeller gradually moves downward. With the increase of pump outlet pressure, the ratio value of the primary impeller compression ratio to the secondary impeller decline tends to flatten; and when the k value is 2.2, the ratio of the compression ratio of the two impellers tends to 1.1.
