NASA 1996 SBIR Phase I


PROPOSAL NUMBER : 96-1 01.04-0045

PROJECT TITLE : Computation of Generation and Convection of Aircraft Vortices

TECHNICAL ABSTRACT (LIMIT 200 WORDS)

A new numerical algorithm, ``Vorticity Confinement,'' is proposed to accurately and economically compute vortices produced by aircraft. Completely Eulerian, the method involves the addition of a self-interaction term to the discretized equations which depends only on the local computed velocity. This term eliminates numerical diffusion and prevents concentrated vortices from spreading due to numerical discretization error. Only 2-3 grid cells are required to resolve the vortices. Vorticity Confinement thus combines the generality and ease of use of Eulerian fixed-grid methods with the efficiency of Langrangian methods for treating concentrated, convecting, and possibly merging vortices. The specific application to be addressed in Phase I is the computation of the flow around aircraft including generated vortex wakes as well as their long term convection in a variety of configurations including cruise and high lift. Currently, full-featured 3-D codes designed to compute the evolution of trailing vorticity in realistic atmospheric conditions, including ground effect, have no satisfactory method of obtaining good starting conditions. Computations using Vorticity Confinement will solve this problem by accurately and efficiently computing the generation and convection of trailing vorticity up to $\sim40$ spans downstream of the aircraft.
POTENTIAL COMMERCIAL APPLICATIONS
The innovative usage of the method will benefit, not only to the present developing comprehensive code, but also to existed computer codes and tools to make them more versatile and efficient. The robust and routine use of the Vorticity Confinement method will enable rotorcraft companies to design more efficient, less costly rotorcraft. It also allows the propeller-driven aircraft, wind mill, sail boat, and automobile industries to be more competitive.
NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR
Yonghu Wenren
Flow Analysis, Inc.
1601, Damron Rd., Estill Springs, TN 37330
NAME AND ADDRESS OF OFFEROR
Flow Analysis, Inc.
256, 93rd St., Brooklyn, NY 11209-6806