A series of experiments have been conducted in the Handley-Page wind-tunnel facility at Glasgow University on two delta wing planforms with sharp leading-edges. The basic delta wing used in the test programme was machined from a solid block of aluminium. It had an 800mm root-chord, and a sweep angle of 60 degrees. This gave an aspect ratio of 2.31 and a trailing edge span of 923.8mm. The wing had a flat leeward surface, a highly contoured windward surface, (giving a thickness ratio of 9.0%) and bevelled edges on the windward side to produce sharp leading and trailing edges. The model had two interchangeable apex sections; one rounded, one sharp. Thus, two different planforms could be studied.

The upper surface of each delta wing was highly instrumented on one side with miniature pressure transducers. These were connected to a powerful two-hundred channel data acquisition system which has the capability to acquire data at the rate of 50kHz per channel. This allowed surface pressure data to be obtained at high spatial and temporal resolution over a wide range of incidence and pitch rates. A series of low-speed flow visualisation tests were also conducted to provide supplementary qualitative flow field information.

The tests were carried out in the University of Glasgow's "Handley Page" wind tunnel which is a low-speed closed-return type. The wing models were located horizontally in its 2.13 x 1.61 metre octagonal working section and supported on three struts, as shown above. These were, in turn, connected to the main support structure and actuation mechanism situated below the tunnel. Movement of the model was produced by displacement of the two rear struts and the model was pivoted about the quarter chord position on a tool steel shaft connected to the front support via two self-aligning bearings. The actuation force was produced using a linear hydraulic actuator and crank mechanism that allowed a variation of angle of attack from -26 degrees to 45 degrees. Each wing was subjected to a range of motion types including ramp-up, ramp-down and oscillatory cycles. The large number of surface pressure transducers on each wing allowed the temporal and spacial evolution of flow structures to be identified and analysed. The three-dimensional stalling process on the delta wing was quite different from those on the other two wings which exhibited a complex interaction between the dynamic stall vortex and the tip vortices. Flow visualisation studies were conducted to aid in the analysis of the pressure data. The main findings of the work, to date, have been extensively reported and analysis is continuing.

For further information please contact: Dr. F. N. Coton.