Measurement of the derivative zw for oscillating wings in cascade

Experimental results are reported of the damping derivative zw. for rigid rectangular wings of various aspect ratios in cascades having gap-chord ratios of 2, 1,1/2, 1/3, 1/4. The results show fair agreement with two-dimensional theory. The ranges of Reynolds numbers and frequency parameters were 0.8 to 2.5 x 10) and 0.1 to 0.45 respectively.

The results show a strong dependence on Reynolds number which increases with decrease in gap-chord ratio. This effect was eliminated by transition fixation by wires placed at suitable positions down-stream of the wing leading edge.