Small Disturbance Navier-Stokes Computations for Low-Aspect-Ratio Wing Pitching Oscillations

摘要

For dynamic production aeroelastic analysis in the transonic speed range, a computational fluid dynamicsmethodnbased on the small disturbance Navier–Stokes equations can serve as a reasonable alternative to one realizing thenReynolds-averaged Navier–Stokes equations’ time-domain solution. Its dynamically linear approach promises ansignificantly decreased computation cost in the prediction of unsteady aerodynamic loading while retaining thenlatter’s fidelity to a high degree. In this regard, research conducted at the Technical University of Munich hasnresulted in the computational fluid dynamics method FLM-SD.NS. Further substantiating its application readiness,nharmonic pitching oscillations of the NASA clipped delta wing are investigated. Test cases are characterized bynshocks of varying strengths and ranges of motion, as well as leading-edge vortex formation. Overall, results are inngood agreementwith dynamically fully nonlinear solutions provided by the comparativeReynolds-averagedNavier–nStokes solver FLM-NS, as well as available experimental data. Reductions in computation time, up to an order ofnmagnitude, in relation to FLM-NS are observed. Limitations of the small disturbance approach, however, becomenapparent for the leading-edge vortex case, in which higher-order harmonics are far less negligible in the flow’snresponse to the excitation.