MODELLING, PERFORMANCE ASSESSMENT AND AERODYNAMIC OPTIMISATION OF A SUPERSONIC THROUGH-FLOW ROTOR

Civil supersonic transport represents the new aviation frontier. Noise regulations constitute the main obstacle to the born of such transport system. Many new engine concepts capable of overcoming such a constrain have been studied. Some preliminary studies suggested that an engine equipped with a fan capable of accepting supersonic inflow could be a suitable and competitive configuration for this market. A supersonic through-flow rotor has been tested by NASA in order to understand the main characteristics and limits of this peculiar concept. Aim of the thesis is to model and optimise the supersonic through-flow rotor focussing on the effects of geometry variations on performance. By using the experimental data released by NASA, a model of such rotor has been designed. The blade is modelled by setting both the blade angle and thickness distributions at three layers: 0%, 50% and 100% of the blade span. The full model is obtained by the interpolation of such distributions on the whole blade span. The model is validated by comparing computational fluid dynamics results with experimental data. Both the design and off-design flow characteristics are appropriately replicated, justifying when possible the rotor performance. At design point conditions, the rotor shows a total pressure ratio of 2.48 and an isentropic efficiency of 77.3%. Once validated, the rotor total pressure ratio and isentropic efficiency are enhanced by modifying both the original blade angle and thickness distributions. The optimisation method is carried out at design point conditions and uses a combination of response surface evaluations and genetic algorithms. The optimised blade shows a broader blade passage, a higher blade loading and a lower blade solidity. As a consequence, the work done on the flow is higher and the skin friction losses are lower. The optimised blade shows a total pressure ratio of 3.03 and an isentropic efficiency of 78.8% at design point conditions.