| The fuel pump is the core component of the aircraft system in the aerospace industry and the power plant of the overall system.In practical engineering applications,the operating environment of fuel pump is very complex,and the impeller blade is prone to cavitation.In this paper,the structure optimization and three-dimensional model construction of the impeller blade of a spiral centrifugal fuel pump are carried out.Based on the cavitation flow characteristics of fuel pump,a mathematical model between the necessary cavitation quantity and dimensionless blade geometry parameters is established.Based on RNG k-εturbulence model and Zwart cavitation model,the cavitation numerical simulation of fuel pump is realized.The cavitation performance of fuel pump was analyzed by combining experimental verification with numerical simulation.The definite flow traits of the fuel pump were acquired,and the effect of the impeller vane architecture on the cavitation identity of the fuel pump was surveyed.The relationship between the head,efficiency,pressure and necessary cavitation allowance of the fuel pump with the blad e sweep angleθand the inlet position coefficientλis analyzed.Obtain impeller blades with high cavitation resistance,so as to achieve the purpose of improving the cavitation performance of the fuel pump.The specific research conclusions are as follow s:(1)The original model of fuel pump was verified by experiments and numerical simulation,and the cavitation characteristics of fuel pump were analyzed.The numerical calculation of the fuel pump shows that the NPSH_r of the fuel pump is 2.97m under 0.6Q_d working condition,while the NPSH_rincreases by 2.36m from 0.6Q_d to1.2Q_d working condition.The pressure,GVF distribution and cavitation development in the impeller channel were observed.It was found that the cavitation resistance of the fuel pump under small flow condition was stronger than that under large flow condition.(2)The models with swept angles of 20°,40°,60°,80°and 100°were designed for the impeller blades of the fuel pump and compared with the original model.The relationship between the external characteristics,cavitation characteristics and cavitation flow field of the fuel pump under these six schemes is analyzed.In ord er to study the relationship between the sweep angle and the necessary cavitation allowance NPSH_r,a correlation function was established.With the increase of the sweep angle,the relative cavitation coefficient decreases from 1 to 0.79 in the range of 0°to 60°;when the sweep angle increases from 60°to 100°,it increases to 1.29.It can be seen that the NPSH_r of the fuel pump with the blade swept back 60°is the smallest,and the cavitation performance of this model is the best.(3)Based on the model of blade swept 60°with the best cavitation performance,the fuel pump impellers with inlet setting coefficientsλof 0.2,0.4,0.6,0.8 and 1 were designed and compared with the original model.The functional relationship between the relative cavitation coefficient and the inlet position coefficientλis established.When the inlet position coefficientλincreases to 0.8,it decreases from 1 to 0.64,and the cavitation property of the fuel pump is progressively heightened;the inlet position coefficientλincreases from 0.8 to 0.64.When it is 1,it increases to 0.75 instead,and the cavitation performance is weakened at this time.When the position coefficient of the inlet edge of the fuel pump blade isλ=0.8,the minimum cavitation allowance must be 3.26m,and the cavitation performance is the best.In summary,the anti-cavitation performance of the fuel pump blade was significantly improved after the modification design of the swept angle and position of the inlet edge.It is of great significance to improve the cavitation performance of fuel pump by optimizing the structure design.The modification design of fuel pump impeller in this paper provides corresponding theoretical support and technical support for practical engineering applications. |
PDF Full Text Request