Experimental and numerical investigation on overall performance of a radial inflow turbine for 100kW microturbine

This paper describes a study on overall performance of the radial inflow turbine for a 100kW microturbine by means of experimental and numerical investigations. All tests are performed with a turbine inlet temperature of 773K and an atmospheric exit pressure, and the rotor rotational speed is ranged from 20000 to 50000 rpm. In addition, the overall performance and the energy loss characteristics for each component of the radial inflow turbine are investigated by 3D Reynolds-averaged Navier-Stokes solutions. The volute, the whole passages of nozzle vanes and rotor, and the exhaust diffuser are meshed with multi-block structured grid. The results of numerical simulation agreed well, as a whole, with that of the experiment both for stage mass flow rate and stage total-static efficiency, which achieved the desired requirements of the design. Based on the results of numerical simulation, the losses of components and exit velocity are analyzed respectively at the off-design conditions. At turbine design point, the losses of volute, nozzle, rotor, exit velocity and exhaust diffuser are about 1.5%, 25%, 43%, 19.5%, 11% of the total loss, respectively, and the rotor incidence angle is basically at optimized value of -23.6° . The losses of rotor and exit velocity change significantly when stage expansion ratio or the rotational speed of rotor altered. In addition, the loss of volute is relative small in the nozzled radial inflow turbine, and then the effect of volute can be neglected in the process of thermal aerodynamic design.