A Three-Dimensional Inverse Method based on Load Control for Radial Inflow Turbine Impeller

摘要

There are surprisingly a few inverse methods found in literature that are composed of clear and definite fluid flow physics. Within this paper one method is proposed to design three dimensional turbine blade shape of uniform thickness. Prescribed mean swirl distribution throughout the meridional flow path was used. Flow is considered inviscid and flow losses through blade passage are taken into account via entropy increase modeling. In order to avoid ambiguity in blade thickness distribution, uniform blade thickness is used to indicate its influence on the velocity field, which may be considerable accurate for impellers of radial inflow turbine. In order to obtain smooth mean swirl distribution, one Laplace equation is used to prescribe over the given flow path region. With given inlet and exit mean swirls of impeller together with possible slopes, mean swirl distribution along meridional surface can be varied freely which then provides further space to seek for optimized impeller geometry shaping. Method was used to design an impeller for a low speed radial inflow turbine as example to show its validity and feasibility.