Publications

Over-wing nacelle (OWN) configurations have two advantages over the traditional under-wing nacelle (UWN) configurations: 1. they make it easier to integrate high bypass ratio (BPR) and ultra-high BPR engines by removing ground clearance concerns, and 2. they significantly reduce noise because the wing blocks the noise of the fan and the jet. Despite their benefits, OWN technology is not widely used in real aircraft designs because of the challenges and lack of research in aeropropulsive integration of the propulsion system. In this work, we present multipoint aeropropulsive design optimizations of an OWN configuration to address several scenarios. To effectively design the propulsor in OWN, we consider on-design and off-design formulations of engine design concepts. In this work, we present one single-point optimization and three multipoint optimizations. In the multipoint optimizations, the objective is to minimize the shaft power at cruise conditions subject to constraints. To compare the performance degradation of single-point optimization, we performed several sub-optimizations to reflect the multipoint cases. The single-point optimal design required additional 0.4% shaft power across the cruise conditions when compared to the multipoint optimization with 3 cruise points. In addition, distortion-constrained and distortion-unconstrained optimizations were performed at the take-off scenario. By modifying the inlet shape of the nacelle, the distortion-constrained optimization effectively reduces the distortion in the take-off scenario at the outermost radial ring over the fan by penalizing the cruise performance. The multipoint optimizations in this work highlight a number of significant design effects. An effective design is produced by including the required flight conditions and specifying the proper objective and constraints in the OWN multipoint problem. These design optimization capabilities will be crucial in determining the viability of novel propulsion concepts for next-generation OWN aircraft.