A comparison of numerical algorithms for unsteady transonic flow
For transonic flow, numerical calculations in two and three dimensions were first achieved with a nonlinear potential equation. Two methods representative of this theory are a numerical algorithm based on a modified form of the small disturbance equation, that is known as the XTRAN3S code and a method based on a numerical solution of the exact full potential equation, known as the USIPWING code. In these formulations the flow is assumed to be inviscid and irrotational. Also, the small disturbance theory makes the assumption that disturbances to the freestream are small, in relation to the freestream velocity, in the vertical direction. A higher-order formulation which alleviates some of the above drawbacks is based on the Euler equations. This formulation has no assumptions regarding weak shocks, irrotationality, or small disturbances in it. Comparison of these three methods shall be made in this paper. This will include a description of the formulation of each method. Also, the range of validity of each method for accurately simulating transonic flow will be indicated. Numerical computations with these methods will be presented for steady and unsteady transonic flow. As a test case, a model of the F- 5 wing, tested by NLR of the Netherlands is utilized. Variations in Mach number, angle of attack, frequency, and lifting surface deflections are considered.
scientific article; zbMATH DE number 4027051
scientific article