Computational investigation of a boundary-layer-ingestion propulsion system

The present paper examines the potential propulsive and aerodynamic benefits of integrating a boundary-layer ingestion propulsion system into the Common Research Model geometry and the NASA tetrahedral unstructured software system. The numerical propulsion system simulation environment is used to generate engine conditions for computational fluid dynamics analyses. Improvements to the boundary-layer ingestion geometry are made using the constrained direct iterative surface curvature design method. The potential benefits of the boundary-layer ingestion system relating to cruise propulsive power are quantified using a power balance method, and a comparison to the baseline case is made. Iterations of the boundary-layer ingestion geometric design are shown, and improvements between subsequent boundary-layer ingestion designs are presented. Simulations are conducted for a cruise flight condition of Mach 0.85 at an altitude of 38,500 ft, with a Reynolds number of 40 million based on the mean aerodynamic chord and an angle of attack of 2 deg for all geometries. The results indicate an 8% reduction in engine power requirements at cruise for the boundary-layer ingestion configuration as compared to the baseline geometry. Small geometric alterations of the aft portion of the fuselage using constrained direct iterative surface curvature are shown to marginally increase the benefit from boundary-layer ingestion further, resulting in an 8.7% reduction in power requirements for cruise, as well as a drag reduction of approximately 12 counts over the baseline geometry.