Evaluation of the Fuel Saving Potential Regarding Recuperated Helicopter Flight Conditions

Incorporating recuperators into turbine engines which enables the heat transfer between exhaust gas and compressed air, indicates considerable potential for lower emissions and SFC (specific fuel consumption). However as a matter of fact, they have not yet found wide acceptance in aircraft applications. One of the main potential disadvantages is because in such situations system overall weight needs to be strictly controlled, and there are concerns that the beneficial fuel saving may not offset the additional bulk and weight of the recuperator. In this work, aimed at evaluating the performance of the recuperated rotorcraft and investigating the influence of a recupeator on the whole system, a comprehensive simulation framework has been developed which mainly contains three modules for various flight conditions: Helicopter performance module (HPM), GasTurb engine simulation module and the recuperator weight estimation. Specifically, HPM calculates the helicopter power requirement for different flight conditions (altitude, speed, etc.), and GasTurb is used to simulate the performance of conventional and recuperated turbine engine, and compute the corresponding engine operating point to meet the power demand. The recuperator weight estimation is mainly based on previous studies as a function of mass flow and effectiveness. The methodology is adopted for a typical twin engine light helicopter configuration. In comparison with the conventional non-recuperated cycle, the authors studied the fuel saving potential of the recuperated cycle for different recuperator effectiveness under various flight conditions, and a trade-off analysis was also conducted to identify the flight time required to compensate the additional recuperator weight. The obtained results suggested that the recuperated cycle possesses great potential, especially for long duration and large range mission, but it may not be necessarily suitable for all types of helicopter missions.