NASA 1998 SBIR Phase I


PROPOSAL NUMBER: 98-1 06.04-3481

PROJECT TITLE: Rapid Prediction of Total Rotor Flows Including Stall and Body Effects Using Sparse Grid CFD Techniques

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

The design and analysis of modern rotorcraft requires computational tools capable oftreating extremely complex aerodynamic problems. These include strong induced flow effects, interactions of the rotor and its wake system, transonic flow, flow reversal, flow separation on retreating rotors, and dynamic stall. Also, the interaction of the rotor wake and other components, such as the fuselage, tail rotor, and wing (for tilt-rotors), are significant. A number of techniques currently exist for computing complete rotorcraft aerodynamic flow fields. These range from comprehensive codes with fast but simplified aerodynamic modelling to full overset-grid Navier-Stokes methods. All have significant drawbacks either associated with inaccuracy or inefficiency. Flow Analysis, Inc. (FAI) has developed several accurate, efficient, and very unique CFD methods for treating rotor systems or bodies. The Vorticity Embedding method has been shown to be the only CFD-based method capable of providing three-dimensional, compressible flows with diffusion-free wakes. The Vorticity Confinement method has been demonstrated to significantly reduce the diffusion problem in Euler/Navier-Stokes methods and for providing efficient rotor body solutions. The current proposal involves the refinement of FAI methods for the modelling of dynamic stall and body flow predictions. The ultimate goal is the coupling of all of these methods. This approach will result in a computational tool that will enable the most efficient and accurate prediction of rotor flows that encompasses the entire spectrum of associated aerodynamic phenomena.

POTENTIAL COMMERCIAL APPLICATIONS

The design/analysis system that will result from the proposed research will enablerotorcraft companies to design more efficient, less costly rotorcraft. Further extensions, in Phase III, should provide a tool that will allow the U.S. aviation industry to be more competitive.

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR

Marvin A. Moulton
Flow Analysis, Inc.
M.S. T19A
Moffett Field , CA 94035-1000

NAME AND ADDRESS OF OFFEROR

Flow Analysis, Inc.
256 93rd Street
Brooklyn , NY 11209-6806