Numerical Simulation of Helicopter Wake Evolution, Performance and Trim.

This paper gives an overview over recent activities in the field of helicopter aeromechanics simulation at the Institute for Aerodynamics and Gas Dynamics (IAG) at the University of Stuttgart. Numerical investigations on hovering isolated rotors in ground effect, main rotor blade shape optimization and finally computations of the entire helicopter in free flight conditions are included. For the hovering rotor good agreement with experimental data has been found for hovering out of ground effect as well as in close proximity to the ground. During our investigations on blade shape optimization a grid convergence study shows asymptotic behavior of relevant parameters such as the power coefficient or control angles. Further generalization of the fluid-structure coupling procedure allows the simulation of a helicopter in free flight condition. The extended coupling and trim method yields good agreement with flight test data. All simulations were carried out on the NEC Nehalem cluster platform of the HLRS and performance was evaluated during one of the optimization computations.