Study on Unsteady Vortex Behaviour of a Rolling Sixty Five Degree (65) Delta Wing at M=0.8 Using Pressure Sensitive Paint (PSP)

摘要

Since the need for improvements in high angle-of-attack maneuverability of aircraft's in transonic flight was of concern, a model was rotated around its longitudinal body axis with a dimensionless rolling rate of pi = 0.0762 (10 Hz), resulting in flow conditions with extensive vortical behavior and strongly non-linear, wing/vortex interference effects. This paper deals with validation experiments performed at the DLR Goettingen. The objective of this activity was to provide experimental data for comparison with numerical calculations performed within the international WEAG TA 15 group: Alenia (Italy) , DERA (United Kingdom), DLR and EADS (Germany), and NLR (The Netherlands). A special 65 delta wing, the DLR PSP-model, was designed, manufactured and finally tested in the transonic 1mx 1m wind tunnel DNW-TWG in Goettingen. A rolling apparatus was built up to enable roll rates up to 10 Hz. A new sting concept was developed as elastic simulations showed dangerous problems associated with the rolling model exposed to the periodic aerodynamic load. The experiments were carried out at angles of attack alpha=10 and 17, M=0.8, Reynolds number of 5.3 Mio in the case of steady and 2.2 Mio for unsteady conditions. The model was equipped with only a few pressure taps for PSI and Kulite sensors, as surface pressure distributions of the model should be obtained using the pressure sensitive paint (PSP) technique, to measure the pressure all over the whole surface of the model. As the model was rotating an unsteady PSP technique had to be applied. Several steps had to be considered in order to finally use the measured pressure distributions for comparison with numerical predictions. In the case of steady conditions the results compare quite well with the conventional pressure taps and numerical calculations, in the case of the spinning model discrepancies between Kulite values and PSP as well as numerical results could be stated.