12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
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 stan-dards 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 vari-able geometry problems. Some complementary elements about the dimensionless meth-ods 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.