Analysis Of Flow-induced Noise Characteristics Of The Screw Mixed-flow Jet Propulsion Pump

The first half of the screw mixed-flow pump is similar to the screw pump,and the second half is similar to the mixed-flow pump,The structure of the mixed-flow pump is an organic integration of the two kind of those impellers.When it works,the propeller has positive displacement characteristics so that it can provide thrust that similar to the propeller,The last part can get thrust through the jet.so the screw mixed-flow pump has a huge application space in the field of water jet propulsion.The research on it Included thrust performance,propulsion efficiency and cavitation characteristics,but there are little related to the field of noise.In this paper,the noise characteristics and distribution of single-blade,splitter-blade and two-blade types of the screw mixed-flow water jet propulsion were analyzed,to learn the noise occurrence law.Then,based on the research above,the noise law of each part of screw mixed-flow water jet propeller under different blade numbers were analyzed in the whole basin.The specific work is as follows:(1)To get the push-drag data by flume test,then complete the design of screw mixed-flow water jet propulsion pump and establish the model set,ICEM was used for grid generation in computational domain,CFX was used to calculate the flow field,by comparing several turbulence models,to select the appropriate boundary conditions,turbulence models and convergence conditions.The calculation results of the flow field are introduced into the sound field,and the sound field is calculated,to analyze the calculation results.(2)The RNG k-e model was used to calculate the constant value of the flow field under different blade numbers,to analyze the influence of different blade numbers on the performance characteristics of screw mixed-flow pump.Taking the steady calculation results as the initial conditions,the unsteady calculation was carried out by using DES model,and the variation law of pressure pulsation on impeller and guide vane surface were monitored by monitoring points under different operating conditions was established,The characteristics of pressure pulsation on the surface of impeller and guide vane in screw mixed-flow pump were analyzed and correlated with the subsequent acoustic calculation results.(3)The unsteady calculation results of flow field are introduced into Virtual lab.The noise characteristics of each flow passage component in the screw mixed-flow pump with different number of blades are calculated by using FEM,to learn the noise variation law of each flow passage component under different flow conditions and the influence of the number of blades on the noise characteristics of the screw mixed-flowpump.(4)The screw mixed-flow pump was used as a power device in the water-jet propulsion system,to learn the influence of different numbers on the thrust performance and operation performance.Then the unsteady calculation was carried out that to analyze the pressure pulsation law of the pump-jet propulsion system corresponding to different revs.(5)The noise characteristics of each flow passage components in the screw mixed-flow water-jet propeller were analyzed.The variation of the noise of the flow passage components at different revs and the influence on the external noise characteristics and distribution were contrasted.