SBIR-STTR Award

Computational algorithms and code will be developed for calculating unsteady compresible 3-D viscous flow and retreating-blade dynamic stall on modern high-performance heliopter rotors. The algorithm development will start from an existing 3-D time dependent viscous compressible code already used successfully to calculate periodic pitching of a swept wing section mounted in a wind tunnel test section. The code uses an approximate factorization (AF) algorithm (including cross derivative terms) in a moving boundary fitted cordinate system with solution adaptive grid generation algorithms, and is highly vectorized for the cray-2. The new code will include the more difficult geometry description of a finite span wing, and turbulence modeling for strongly separated flows including centri- fugal forces. The phase II code will also be applicable to complex motions and to fully coupled aeroelasticity calculations.

Computational algorithms and code will be completed for calculating unsteady compressible 3-D viscous flow and retreating-blade dynamic stall on modern high-performance helicopter rotors. Present code features include the approximate factorization (AF) algorithm, a moving boundary fitted coordinate system, solution adaptive grid generation, K-omega turbulence model including rotational/curvature and unsteady effects, and will be adaptable to fully coupled aeroelasticity calculations. Phase II funding will produce a user-friendly and efficient code to model the dynamic stall problem with useful engineering accuracy. The capability to accurately calculate the unsteady flow and retreating-blade dynamic stall for realistic and innovative rotor blade shapes will contribute significantly to the ability to design high-performance helicopter rotor blades with reduced vibrations and greater maneuverability.