| Cavitation process includes vapor from initial generation,development to collapse,especially in the process of vapor collapse,this process will lead to some harmful phenomena in the hydraulic machinery,such as pressure fluctuation and high-frequency noise,affecting the stability and safe operation of the machine set.The cavitation will lead to the deterioration of the external characteristics of the centrifugal pump,as well as the vibration and noise.The pressure impact caused by vapor collapse will cause the erosion damage to the solid wall of the flow passage parts of the fluid machinery,that is,cavitation erosion.High-speed fuel pump as an important fuel supply part of aeroengine,it’s cavitation performance is the key point to ensure its reliability.Adding inducer is the most effective measure to improve the cavitation performance of centrifugal pump,so it is of great significance to study the influence of inducer on the cavitation performance of high-speed fuel pump.In this paper,Based on the numerical calculation,the key hydraulic components of the high-speed fuel pump variable pitch inducer as the research object.The influence of the tip clearance of inducer and the change of bl ade axial section angle on the cavitation performance of high-speed fuel pump is studied.The specific research contents are as follows:1.The cavitation development process of high-speed fuel pump and the cavitation performance under different flow rates are studied.The head of high-speed fuel pump decreases with the increase of flow,and the efficiency increases with the increase of flow because the impeller is of low specific speed.Combined with the cavitation performance curve,the cavitation evolution of inducer and impeller cascade and the distribution of vapor in the passage,the cavitation performance of high-speed fuel pump under different working conditions,with the increase of flow rate,the vapor in the passage increases rapidly,the number o f fracture cavitation of high-speed fuel pump increases,the position of cavitation fracture of fuel pump moves forward,and the head drops earlier.2.The effect of tip clearance of inducer on cavitation performance of high-speed fuel pump was studied.With the increase of tip clearance of inducer,the critical cavitation number and fracture cavitation number in cavitation performance curve of high-speed fuel pump increase,and the cavitation performance becomes worse.The interaction between the tip clearance flow and the main flow forms a shear flow region at the upstream of the inducer.The region with large velocity and small pressure and large energy loss caused by the vortex in the region is the place where cavitation is easy to occur.When cavitation occurs,it is easy to form asymmetric spiral vortex cavitation.When the tip clearance of the inducer increases,the influence of the clearance flow on the shear layer flow increases,and the vortex at the upstream of the inducer increases.The increase of vapor leads to the deterioration of flow condition in the channel.3.The influence of the change of the angle of the blade section of the variable pitch inducer on the cavitation performance of the high-speed fuel pump was studied.The cavitation performance of the high-speed fuel pump will be improved when the pitch of the blade changes within a certain range.However,when the angle is too large,the flow separation will be intensified,which will aggravate the cavitation development of the high-speed fuel pump.In this study,the high-speed fuel pump obtains the best cavitation performance when the angle of the axial section of the induce r blade section is θ = 2 °.The change of the caster angle of the inducer blade section on the axial surface can fine tune the blade angle of the inducer inlet edge and the hub.When the angle of the blade section is changed,the inlet blade angle at the inducer edge will be increased,the matching of the liquid flow angle and the blade angle will be improved,and the flow separation will be reduced,so that the cavitation performance of the inducer will be better.However,when the angle exceeds a certain range,the negative impact angle will be increased.The cavitation performance is poor due to severe flow separation. |
