Preliminary Design Considerations for Variable Geometry Radial Turbines with Multi-Points Specifications

Pierre-Thomas Lauriau,Xavier Carbonneau,Mathieu Roumeas,Nicolas Binder,Sandrine Cros

doi:10.3390/ijtpp3040022

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, related to the improvement of the operating range. As preliminary design correlations and standards usually taken into consideration arise from studies dedicated to fixed geometry radial turbines, 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.

Highlights

Radial inflow turbines are currently employed in many industrial applications, such as automotive turbochargers, cryogenics or air-conditioning systems
It makes the design more challenging because the variable geometry turbine stage efficiency must be acceptable for a wide operating range
This paper provides some theoretical basics in order to help designers considering variable geometry problems

Summary

Introduction

Radial inflow turbines are currently employed in many industrial applications, such as automotive turbochargers, cryogenics or air-conditioning systems. In addition to their relatively low-cost manufacturing and compactness, they provide a specific mass flow and a rotational speed for a given pressure expansion. The improvement of the operating range provided by this technology forecasts the development of a new architecture of Environmental Control Systems (electrical system). It makes the design more challenging because the variable geometry turbine stage efficiency must be acceptable for a wide operating range. The turbine stage should be designed directly from a multi-points specification, for which the first order information is sometimes difficult to extract

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