This study is concerned with a variable geometry inward flow radial turbine for turbocharging Diesel engines. A detailed theoretical and experimental investigation in both the stator and rotor is presented. The finite element method being applied for the flow analysis. The finite element procedure was initially developed by applying it to an isolated aerofoil prior to the further application to cover a circular cascade of blades as encountered in the volute-nozzle assembly. In the rotor, only the hub-shroud analysis was carried out and the results compared with an existing streamline curvature technique. It was shown that the finite element method required less computaional time and was more generally applicable to complex geometric configurations than the streamline curvature technique. Experimentally, the turbine performance was evaluated with and without exhaust diffusers and with a number of nozzle rings with different restrictions. It was shown that the maximum restriction resulted in high losses due to the flow mismatching at nozzle inlet because of the sudden area change, and relatively low efficiencies resulted. The effect of swirl, resulting from off-design operation, on the diffusers was analysed with three conical diffusers. The results show that low swirls of the order of 10%, has a beneficial effect on the pressure recovery coefficient for wide angle diffuser.
|Date of Award||1983|