Results of a new version of the LTRAN2-NLR code (LTRANV) for unsteady viscous transonic flow computations

Report (1981)

Authors

R. Houwink

Computational fluid dynamics Transonic flow Flaps Unsteady flow Pressure distribution Aerodynamic coefficients Lift Wing oscillations Viscous flow Computer programs Thin airfoils

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Published Date

07-07-1981

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NLR-TR 81078 U

Abstract

An outline is given of a first version of the computer programme LTRAFV for coupled unsteady transonic flow/turbxilent boundary layer computations. It is a combination of the LTRAN2-NLR programme and the lagentrainment method of Green. A comparison is made of theoretical and experimental results for the NACA64A006 airfoil with oscillating flap in subsonic and transonic flow. Accounting for the effect of the boundary layer on the airfoil yields a reduction of the magnitude of unsteady airloads by 10-35 % and a phase shift of 2 to 7 degrees. As a result, a generally better agreement with experimental data is obtained. Considerable differences between theory and experiment at low reduced frequency are likely due to strong wall interference effects and some underestimation of the boundary layer effect. The use of a steady boundary layer method instead of an unsteady one is acceptable for the cases considered

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