Transonic Wing Design Using Potential-Flow Codes - Successes and Failures

An overview of the state-of-the-art of transonic wing design by use of computer codes based on potential-flow theory is presented. Several recent experiment-theory correlations have been cited to give the reader an indication of the capabilities and limitations of these codes. The examples include correlations of experimental pressure distributions with theoretical results from isolated wing and wing-body codes. Computer codes using both conservative and nonconservative differencing schemes are used in this study and the effects of boundary-layer corrections are considered. The results show that calculations from a full potential, isolated wing code correlate well with data from an isolated wing test but may give poor predictions of the aerodynamic characteristics of some wing-body configurations. The potential-flow, wing-body codes used in this study gave better estimates of wing-body aerodynamic characteristics than isolated wing codes in some cases while in other wing-body cases, results given by the isolated wing code agreed better with experiment than those given by the wing-body codes. Boundary-layer corrections were found to have only moderate effects on experiment-theory correlations. The effect of aeroelastic distortions under load were found to have a greater effect on experiment-theory correlation than viscous correlations for an isolated wing test. A wing-body code was used to calculate the flow field about a wing-body configuration with body-mounted engines, which is typical of the transonic “Biz-Jet” class of aircraft.