Numerical Studies of Unsteady Transonic Flow Over an Oscillating Airfoil


Book Description

A finite-difference solution to the Navier-Stokes equations combined with a time-varying grid-generation technique was used to compute unsteady transonic flow over an oscillating airfoil. These computations were compared with experimental data (obtained at Ames Research Center) which form part of the AGARD standard configuration for aeroelastic analysis. A variety of approximations to the full Navier-Stokes equations was used to determine the effect of frequency, shock-wave motion, flow separation, and airfoil geometry on unsteady pressures and overall air loads. Good agreement is shown between experiment and theory with the limiting factor being the lack of a reliable turbulence model for high-Reynolds-number, unsteady transonic flows. Chyu, W. J. and Davis, S. S. Ames Research Center NASA-TM-86011, A-9857, NAS 1.15:86011
















Unsteady Transonic Flow


Book Description

This classic monograph on unsteady transonic flow — the flow of air encountered at speeds at or near the speed of sound — is of continuing interest to students and professionals in aerodynamics, fluid dynamics, and other areas of applied mathematics. After a brief Introduction, Swedish physicist Mårten T. Landahl presents a chapter in which the two-dimensional solution is derived, succeeded by a discussion of its relation to the subsonic and supersonic solutions. Three chapters on low aspect ratio configurations follow, covering triangular wings and similar planforms with curved leading edges, rectangular wings, and cropped delta wings, and low aspect ratio wing-body combinations. The treatment concludes with a consideration of the experimental determination of air forces on oscillating wings at transonic speeds.




Computational Research on Inviscid, Unsteady, Transonic Flow Over Airfoils


Book Description

The inviscid transonic flow over an NACA 64A410 airfoil oscillating in pitch in a Mach 0.72 stream was calculated with a program based on the unsteady Euler equations. The airfoil oscillates about a mid-chord axis with attitude alpha = 1 deg + or - 1 deg at reduced frequency k = omega C/U(infinty) = 0.2. The effects of two approximations made in the analysis, handling of boundary conditions at the airfoil surface and at the perimeter of the computation field, have been studied. (Author).