Suction-slot ducting design

Abstract

Summary.--Purpose of Ducting.--To provide uniform suction through a narrow slot along tile span of a wing, with the lowest possible losses, when the pump is situated at the root of the wing. Range of Investigation.--Models of various design were tested and modified in the light of the results obtained. From these experiments, together with a qualitative analysis of the flow through the type of ducting proposed, specific recommendations have been formulated for the attainment of uniformity of suction combined with low power losses. Investigations were confined to suction from still air. Results.--Losses of about 0.2ql were obtained with the broad partition and with the guide-vane ducts, compared with about 0.7ql for the earlier models, and the distribution of velocity at the slot was quite satisfactory. The circular collector duct appeared to be more efficient, but suction was much higher at the tip than at the root. Future Developments.--Suction ducting is to be tested in the wall of a small wind-tunnel, so that the effect of the tunnel boundary layer may be studied.