Numerical Simulation And Application Research Of Fuel Vapor Core Pump With Straight Radial Blades

The outstanding flow governing makes VCP(Vapor Core Pump) possible to have prospective application in the fuel system of aircraft engines. Clearly recognizing VCP’s working mechanism and improving its design technique, as well as developing the VCP prototype, have great significance to the development of fuel pumps used in domestic aircraft engines.According to the structure and size of the prototype, the geometric model of the whole VCP was built including the pump inlet channel, the inlet throttle device, the enclosed impeller with radial straight blades, the spiral volute, the conical diffuser and the pump outlet. High quality mesh model was obtained by using the pre-processing software ICEM CFD. Unsteady numerical simulation on VCP with vapor-liquid two-phase cavitation model was carried out with ANSYS FLUENT, a commercial CFD software tool. The accuracy of numerical model was verified by comparing with the pump prototype testing results.The reasonable scope of vapor core region was obtained according to the numerical analysis on the influence of its morphology on pump performance under small inlet valve opening conditions, based on RNG k-epsilon turbulence model and Zwart-Gerber-Belamri cavitation model. Analysis on the vapor core morphology and the pump performance under different inlet pressure indicates that, when not approaching the blade outlet edge, the vapor core had little influence on the pump performance. In contrast, the pump efficiency rapidly falls off. Therefore, the VCP should be avoided operating on the condition that the vapor core region approaches the blade outlet edge.In order to obtain the optimal number of blades, numerical simulation on VCP with 20, 18, 15, 12, 9 and 6 blades was carried out, respectively. The results show that when the number of blades decreases from 20 to 9, pump head has a slight rise and pump efficiency changes little. Compared with 20 blades, the impeller with 9 blades can have about 20% reduction in weight. And amplitude of the pressure pulsation at the outlet of the 9-blade pump is within 2.5% but 8% for the 6-blade pump.Study on the pressure pulsation and flow behavior of the 9-blade VCP show that the static pressure increases first from the volute tongue and then decreases and rises again along the volute circumferential direction. The blade passing frequency has much influence on the pump pressure pulsation. Volute tongue is one of the main reasons for vortex generation and the vortex mainly distributes in the blade passages near the volute tongue.