Description: This SBIR project proposes to develop a computational tool for helicopter rotor noise prediction based on hybrid Cartesian grid/gridless approach. The uniqueness of this approach is to achieve fully automated grid generation without grid overlapping. As a result, the resulting software will enjoy great ease of use with minimum human interference. There is no grid distortion in the majority of the computational domain. One can apply the best available flow solver which may not be possible to use in the unstructured grid approach. All are important for achieving accurate prediction of helicopter rotor aerodynamics and near-field acoustics. In Phase I, the high-speed impulsive noise will be first investigated and in Phase II, the blade-vortex interaction noise will be further explored.

Benefits: The developed software can be used by helicopter industry like Bell Helicopter, Sikorsky, and Boeing for prediction of helicopter rotor aerodynamics and near-field acoustics. NAVAIR can use it to investigate the interaction of helicopter and ship air wake.

Both military concern of detection and community concern of noise pollution have stimulated NASA to actively pursue various noise reduction techniques. This further pushes NASA to look for external noise prediction methods for manned and unmanned rotorcraft. The proposed computational tool can be used by NASA to explore on-blade active flow control techniques such as zero-mass jets.