Numerical calculation of pressure fluctuation in contra-rotating axial flow waterjet pump
WANG Xuebao1, PAN Zhongyong1, HUANG Dan2, ZHANG Xiao1, HUANG Zhenjie1
1.National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2.Xi′an Aerospace Propulsion Institute, Xi′an, Shaanxi 710100, China
Abstract:The unsteady pressure fluctuations in an optimally designed contra-rotating waterjet axial flow pump are identified by using unsteady numerical simulation under design condition based on CFD method with the SST k-ω turbulence model. A mesh independence analysis shows that the calculated power and head are well consistent with the design data. The monitoring points are mounted at the inlet of front impeller, in the tip region of front and rear impellers, in the axial clearances and at the diffuser inlet. The time domain pressure fluctuation data are recorded at each monitoring point, meanwhile the pressure fluctuation characteristics are analyzed and compared in both time and frequency domains. The simulation results indicate that pressure fluctuation is mainly affected by blade passing frequency, however, the fluctuation in the tip region of the front and rear impellers depend on the number of blades and impellers. Influenced by reverse rotation of the two stage impellers, the pressure fluctuation amplitude in the axial clearance between the front impeller and the rear impeller is the maximum. The pressure fluctuations at the rear impeller outlet and diffuser inlet are mainly influenced by reverse flow from the diffuser.
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