Aerodynamic Design of a Radial Inlet Air Turbine Stage

The customer, one of the leading suppliers for aerospace companies, asked ADT to carry out the complete aerodynamic design of a radial inflow turbine stage using inverse design approach available through the TURBOdesign Suite software. The turbine is to be used for expanding air to drop its temperature to very low value for a high altitude testing.

The turbine had to be point designed to deliver the right mass flow at right temperature for the given pressure ratio with a limited power delivery. The rated rotational speed is also specified. This represents a closed set of performance constraints.

Fig. 1: Meridional geometry of the rotor and nozzle from TURBOdesign Pre.

Turbine Design

The aim of the project was to design a single stage radial inlet air turbine for high altitude test application. Turbine is expected to deliver the required mass flow of air at a required temperature keeping the power within limits at the given expansion ratio. The single stage turbine meeting the specifications within the allowed margin was delivered on time along with the performance map.

The inverse design approach ensured that the performance requirements are met with in a couple of design iterations. Even though each component is designed separately, TURBOdesign1 ensured proper matching between the components since it uses the outflow conditions of each component as the inflow boundary conditions for the following one. 

Fig. 2: Velocity streamlines through the turbine stage.

Inlet volute is designed using TURBOdesign Volute which is also an inverse design software. This inverse design approach produced a properly sized volute for the turbine. Fig. 2. above shows the streamlines through the turbine. CFD analysis of the final design showed that the required mass flow, temperature and power specifications are met.