Numerical Simulation Of Flow Field In Partially Intake Turbine

If the full-circumference air intake is used to do work on the short-sized blades in the underwater low-speed vehicle power system,the size of the beveled nozzle will be too small,so that the nozzle design difficulty and flow loss will be increased.Therefore,the partial intake turbines have become a common power unit for such low-speed vehicles.The internal flow of the partial intake turbines is very complicated.the interference effects of the inlet shock wave and the blade boundary layer and local secondary flows and leakage flows due to the gas viscosity causes the property of 3-D and rotation in the cascade flow channel.Geometric factors and aerodynamic factors have a great impact on the flow in the turbine.Thus it is necessary to investigate the influence of such factors to provide some reference for improving the turbine working efficiency.Firstly,one-dimensional thermodynamic calculation and three-simulation for micro-experimental turbines in the literature is performed.The results verify the rationality of thermal calculations and simulations.Then,the conventional 3-dimensional partial intake turbine is modeled.The static blade adopts a Laval nozzle;the moving blade adopts an impulsive blade,and the intake mode is partial intake.Through the combination of one-dimensional thermodynamic calculation and three-dimensional simulation,the rationality of the model and calculation method is verified,and the flow field inhomogeneity and the shock wave phenomenon in the moving blade domain are analyzed briefly.Secondly,the effect of changes in local structure on power is discussed.By changing model dimensions of the blade partial inlet,axial clearance,radial clearance and nozzle expansion angle,the variation of flow loss in the turbine is analyzed.The effects of end loss,nozzle energy loss,moving blade energy loss and air loss are mainly studied.From the point of the blade component torque and the moving blade pressure coefficient,the reasons that affecting the total torque of the turbine are analyzed.Finally,the flow characteristics of the turbine under non-design conditions are numerically simulated to analyze the changes in the entropy efficiency of the turbine.By changing the inlet temperature,the variation law of nozzle and moving blade enthalpy drop distribution is studied.By changing the inlet total pressure,the change law of the energy lossof the moving blade is mainly investigated.By changing the rotate speed,the inlet velocity triangle of the moving blade is also studied.At last,the conclusion is drawn that the design efficiency is the highest.