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NASA NTRS · 20140017731

Time-Spectral Rotorcraft Simulations on Overset Grids

Leffell, Joshua I.·Murman, Scott M.·Pulliam, Thomas H.
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Abstract

The Time-Spectral method is derived as a Fourier collocation scheme and applied to NASA's overset Reynolds-averaged Navier-Stokes (RANS) solver OVERFLOW. The paper outlines the Time-Spectral OVERFLOWimplementation. Successful low-speed laminar plunging NACA 0012 airfoil simulations demonstrate the capability of the Time-Spectral method to resolve the highly-vortical wakes typical of more expensive three-dimensional rotorcraft configurations. Dealiasing, in the form of spectral vanishing viscosity (SVV), facilitates the convergence of Time-Spectral calculations of high-frequency flows. Finally, simulations of the isolated V-22 Osprey tiltrotor for both hover and forward (edgewise) flight validate the three-dimensional Time-Spectral OVERFLOW implementation. The Time-Spectral hover simulation matches the time-accurate calculation using a single harmonic. Significantly more temporal modes and SVV are required to accurately compute the forward flight case because of its more active, high-frequency wake.

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Leffell, Joshua I., Murman, Scott M., Pulliam, Thomas H.. 2014-06-16. Time-Spectral Rotorcraft Simulations on Overset Grids. https://ntrs.nasa.gov/citations/20140017731

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