Numerical Simulation of the Velocity Coefficient of Low-Flow Turbine Impeller

The work considers modern marine turbomachines, which differ in type, design, purpose, material, and working fluid. It is noted that this diversity is caused by modern computer technologies used from the stage of preliminary preparation of production to the release of final products. The paper considers the design stage of turbine units, taking into account the external characteristics of the turbine stage, specifically the power, rotation frequency, efficiency, shaft torque, etc. The effectiveness of the turbine stage is expressed by the efficiency, which is determined by the energy losses taking place in the stage. In turn, total losses are expressed by losses in each individual structural element of the turbine stage. Thus, the losses in the impeller include friction, lip, and end losses. The study object is the impeller of a low-flow inflow turbine, while the subject of the study is the velocity coefficient of the impeller of such a turbine. The purpose of the study is to compare the velocity coefficients of the impeller obtained during the physical experiment with the results of numerical simulation. The research method is based on numerical simulation of gas flow using computational fluid dynamics (CFD). The main objective of the study is to compare the velocity coefficient of the impeller obtained during a physical experiment with the results of numerical simulation of the impeller with subsonic (narrowing) channels. The conducted studies have shown that low-flow radial turbines are characterized by small dimensions that do not allow performing a physical experiment. The study presents a graph showing the dependence of the velocity coefficient of the impeller on the Mach number. A good agreement of the velocity coefficients of the impeller determined by the numerical simulation with the results of the physical experiment is achieved. The velocity fields of the flow part of the impeller are obtained in the range of the Mach number of 0.66–0.88. Conclusions are drawn about the possibility of using numerical simulation for this type of impellers.