A procedure for the design of radial cascade diffusers based on the maximum ratio between flow deflection and total pressure loss coefficient

Abstract

A design procedure of radial cascade diffusers for incompressible flow, based on the maximum ratio between the flow deflection and the total pressure loss coefficient, is proposed. To achieve such a result, numerical investigations were carried out on several different diffusers at design and off-design operating conditions. Four space chord ratios, with seven blades and nine outlet flow angles were considered. For each diffuser, the optimum performance parameters were correlated to the incoming flow angle and the design variables of the aerofoil cascade. Reynolds number and mean camberline influence were also analysed. Design charts were then produced in order to attain an efficient preliminary design of aerodynamic diffusers without resorting to time-consuming approaches. Finally, auxiliary charts were proposed for predicting the diffuser performance at off-design operating conditions.