A Preliminary Design Tradeoff Study for an Advanced Propulsion Technology Rotorcraft at Mission Level

This paper aims to present an integrated rotorcraft (RC) multidisciplinary simulation framework, deployed for the comprehensive assessment of combined RC–powerplant systems at mission level. The proposed methodology comprises a wide-range of individual modeling theories applicable to RC performance and flight dynamics, as well as the gas turbine engine performance. The overall methodology has been deployed to conduct a preliminary tradeoff study for a reference simple cycle (SC) and conceptual regenerative twin-engine-light (TEL) and twin-engine-medium (TEM) RC configurations, modeled after the Airbus Helicopters Bo105 and Aérospatiale SA330 models, simulated under the representative mission scenarios. The installed engines corresponding to both reference RC are notionally modified by incorporating a heat exchanger (HE), enabling heat transfer between the exhaust gas and the compressor delivery air to the combustion chamber. This process of preheating the compressor delivery air prior to combustion chamber leads to a lower fuel input requirements compared to the reference SC engine. The benefits arising from the adoption of the on-board HE are first presented by conducting part-load performance analysis against the reference SC engine. The acquired results suggest substantial reduction in specific fuel consumption (SFC) for a major part of the operating power range with respect to both RC configurations. The study is further extended to quantify mission fuel burn (MFB) saving limit by conducting an extensive HE tradeoff analyses at mission level. The optimum fuel burn saving limit resulting from the incorporation of on-board HEs is identified within realistically defined missions, corresponding to modern RC operations. The acquired results from the mission analyses tradeoff study suggest that the suboptimum regenerated RC configurations are capable of achieving significant reduction in MFB, while simultaneously maintaining the respective airworthiness requirements in terms of one-engine-inoperative. The proposed methodology can effectively be regarded as an enabling technology for the comprehensive assessment of conventional and conceptual RC–powerplant systems at mission level.