Powered turbofan effects on aircraft aerodynamics at high-lift: A study on the NASA CRM-HL

High-lift operating conditions of aircraft are known to comprise a series of complex physical features, making the three-dimensional flow difficult to discern and analyse. In such scenario, the effect of underwing engine installation, especially in the case of large-diameter ultra-high bypass ratio turbofans, has been little investigated. In this paper, we present a numerical study on the NASA High-Lift Common Research Model aircraft with powered turbofan engines, focused on the effect of propulsion system integration. A validated Computational Fluid Dynamics model is first employed to analyse the aerodynamics along the wing polar, at an angle of attack up to , close to near stall. The flow field on the suction side of aerodynamic surfaces is qualitatively similar to previous results obtained at lower Reynolds number for a throughflow nacelle, whereas on the pressure side a relevant distortion is present near the stall. The same case is simulated again by using a fully coupled Body Force Model fan stage representation, further inspecting the flow past the nacelle, the distribution of the propulsive forces, and the sensitivity of the fan working point to the operating incidence. The analysis reveals the complexity of the three-dimensional flow and the large azimuthal redistribution occurring on the nacelle, relative to an isolated configuration.