| The hydrogen fuel turbine range extender is composed of a compressor,a combustion chamber,and a turbo expander.It uses hydrogen as energy and can effectively improve energy utilization.The turboexpander is an important part of the hydrogen fuel turbo range extender,and its efficiency directly affects the overall efficiency,so it is necessary to carry out design research and performance analysis on it.The main research contents of this paper are as follows:The one-dimensional design theory of the turboexpander is introduced,the key design parameters are selected,the thermal calculation of the centripetal turbine is carried out through the key parameters,and the aerodynamic parameters of the volute,the vane and the impeller are determined.Use ANSYS to process its geometric structure and perform numerical simulation to analyze the internal flow characteristics of the turboexpander.Numerical simulation results show that the thermal calculation results of the centripetal turbine are basically consistent with the simulation results,verifying the feasibility of the one-dimensional design method,and the isentropic efficiency of the centripetal turbine can reach 92.56%.The overall performance of the centripetal turbine is better,the pressure drop distribution and streamline distribution are more reasonable,and there is no obvious secondary flow and backflow area in the flow channel area.Study the flow characteristics of the radial turbine volute under design conditions and the flow characteristics under non-design conditions.The results show that the flow lines inside the volute are smoothly distributed and the pressure drop is uniform;the flow and velocity of the fluid inside the volute are different,so the flow lines move in a spiral motion;the internal losses of the volute are mainly concentrated on the inner wall of the volute and the throat area;The shell has good applicability under non-design conditions.Investigate the influence of different speeds on the impeller configuration and internal flow characteristics.The results show that under the same initial parameters,the lower the speed,the greater the curvature of the impeller blades,the overall flatness of the impeller and the lower the efficiency of the turbine;the lower the speed of the same turbine at different speeds,the more obvious the vortex return at the impeller inlet.Produce a larger back pressure area,causing greater losses.In response to this phenomenon,the use of circular inlet impeller blades will reduce the vortex return area and increase the turbine efficiency.The loss of fluid in the guide vane area was studied.The results show that the fluid in the guide vane channel area is basically smooth,and there is no channel vortex.The main loss is that the fluid forms a wake flow in the exit area of the blade.The wake flow is generated because the fluids with different flow speeds and directions at the two ends of the blade meet.Explore the influence of the tip clearance in the impeller area on the mainstream.The results show that the influence of the tip clearance on the fluid inside the turbine is mainly concentrated in the rear half of the impeller.The larger the tip clearance in this part,the more obvious the leakage will be,and the leakage will form a leakage vortex here.By reducing the gap in this area,leakage can be effectively suppressed and the efficiency of the turbine can be improved. |
