Experimental Investigation of Asymmetry of Vortex Flow Over Single Delta Wings

It is generally believed that, on slender delta wings, there is a critical state at which strong asymmetric vortices are found along the leading edge on the lee-side of the delta wing. These asymmetric vortices can lead to high lateral forces even when slender delta wing is at the zero angle of yaw. Some experimental studies reported recently, cast considerable doubt as to the validity of the above explanations. A wind tunnel investigation was, therefore, performed to study afresh this phenomenon. The flow over four sharp edged delta wings with aspect to a ratio ranging of 0.56 to 1.46 was investigated using flow visualization with laser light sheet and some surface pressure as well as hot wire measurement. The tests were conducted for angles of attack ranging from 0 to 30 deg and at a free-stream velocity of 30m/s corresponding to a Reynolds number of $4.8 times10^{5}$ based on the center line chord of the wing. The results obtained suggest the absence of asymmetry in the vortex core position in the flow.