Enhanced High-Order Scheme for High-Resolution Rotorcraft Flowfield Analysis

Abstract

The recent growing interest in urban air mobility (UAM) worldwide has led to the demand for physical analyses of the aerodynamic performance and aeroacoustic characteristics of electric vertical takeoff and landing (eVTOL) rotorcraft. In a UAM eVTOL rotorcraft, the smaller vortices generated from multiple propulsors interact with lifting surfaces such as wings, fuselage, and propellers in a complex manner. Therefore, to accurately predict the performance and noise of UAM eVTOL rotorcraft, vortices should be preserved with little dissipation; and their interactions must be modeled precisely. These requirements need a numerical algorithm with a refined resolution than that allowed by conventional schemes. This paper proposes a newly modified enhanced multidimensional limiting process (eMLP) for vorticity conservation (eMLP-VC), which improves the original eMLP by accounting for the fact that most rotorcraft flowfields are vortex dominated and subsonic. For advanced capability in preserving vortices, the distinguishing criterion was modified through vortex profile analysis, and low-Mach-number adjustment was performed by reconstructing the interpolated primitive variables. The proposed scheme was applied to wave propagation, shock discontinuity, double Mach reflection, propeller–wing interaction, and Second Higher-Harmonic Control Aeroacoustic Rotor Test problems. The computed results confirmed that eMLP-VC exhibits superior resolution, numerical stability, and computational time efficiency as compared to the multidimensional limiting process, eMLP, and weighted essentially nonoscillatory methods.