Preliminary design considerations for variable geometry radial turbines with multi-points specifications

Abstract

Radial turbines preliminary designs are usually carried out through some dimensionless approaches, such as the loading-to-flow-diagram and/or the blade speed ratio. In case of variable nozzle radial turbines, multi-points specifications must be considered, associated to the improvement of the operating range. As preliminary design correlations and standards usually taken into consideration arise from fixed nominal geometry radial turbines studies, they need to be updated with regard to nozzle off-design opening configurations. This paper provides some theoretical basics in order to help designers considering variable geometry problems. Some complementary elements about the dimensionless methods are given by taking into account the nozzle opening effect. Then useful considerations are brought regarding the preliminary design of variable geometry radial turbines with multi-points specifications.