Date of Award
Master of Science
James G. Coder
Ryan S. Glasby, Stephanie C. TerMaath
A four-blade helicopter rotor is modeled using computational fluid dynamics (CFD), and the impact on the flow-field with and without a floating fuselage geometry is assessed. The numerical predictions were made with CFD simulations using the NASA OVERFLOW 2.2n solver. For numerical simulations, the flow-field was discretized in a structured, overset topology with grids intended to solve the scope of the problem. Results based on a tip Mach number of 0.58 were acquired for various collective pitch angles. The simulations were completed with the Spalart-Allmaras (SA) one equation eddy-viscosity turbulence model along with the Spalart-Shur rotation/curvature correction coupled with the amplification factor transport (AFT) transition model. Additionally, Delayed, Detached Eddy Simulation (DDES) was used to induce hybrid RANS/LES behavior. Overall predicted figure of merit and laminar-to-turbulent transition patterns on the blade surfaces with and without the fuselage exhibited reasonable agreement with experimental data. Specifically, laminar-turbulent transition patterns on the blade surfaces at 10° collective pitch showed better agreement with experimental data than at 8° collective pitch. It was observed from the simulations that the blade root and tip vortex systems become increasingly unstable as the collective pitch is increased for both configurations.
Parwani, Ashwin, "A STUDY OF THE EFFECTS AND SIGNIFICANCE OF TRANSITION MODELING FOR ROTORCRAFT APPLICATIONS. " Master's Thesis, University of Tennessee, 2018.