What was learned from numerical simulations of F-16XL (CAWAPI) at flight conditions

• Ten groups participating in the CAWAPI project have contributed steady and unsteady viscous simulations of a full-scale, semi-span model of the F-16XL-I aircraft at three different categories of flight Reynolds/Mach number combinations for comparison with flight-test measurements for purposes of code validation and improved understanding of the flight physics of complex interacting vortical flows. The steady-state simulations are done with several turbulence models of different complexity with no topology information required and which overcome Boussinesq-assumption problems in vortical flows. Detached-Eddy Simulation (DES) has been used to compute the unsteady flow. Common structured and unstructured grids as well as individually-adapted unstructured grids have been used. Although discrepancies are observed in the comparisons, overall reasonable agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles. The physical modeling, steady or unsteady, and the grid resolution both contribute to the discrepancies observed in the comparisons with flight data, but at this time it cannot be determined how much each part contributes to the whole. Overall it can be said that the technology readiness of CFD-simulation technology for the study of vehicle performance of e.g. the F-16XL has matured since 2001 such that it can be used today with a reasonable level of confidence in practical use.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Farkostteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Vehicle Engineering (hsv//eng)

Nyckelord

Computer simulation

Mach number

Mathematical models

Steady flow

Unsteady flow

Viscous flow

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