Two-dimensional Pressure Distribution Tests on IO per cent Thick Symmetrical Aeroforl Section

Lsminar Boundary Layer Separation In this report the term "bubble vortex" (Sect. 6.1. et seq.) has been used to describe the rotatug mass of air lying parallel to the leading e&c near the aerofoil nose under the separated boundary laycr. It is now felt that the use of vortex in this context is misleaw, since the air movcrilent in the "bubble" may not rcscmble that in a true vortex. The term "separation bubble" is therefore suggested to replace "bubble vortex" whenever it ocours in the text. that the liquid filn noved over the wug surface solely under the influence of the shear stress unposed upon it by the traction of the boundary layer flow above; it has now been swested that the film nqy also follow pressure gradients existing on the wing surface. The particular conhtions which favour one influence more than the other have not yet been established, but sme work is at present in progress which, it is hoped, will revedl the main factors oontrollirg the movement of liquid films. Interpretations nadc in this paper of the liquid filn p&tern should therefore be regarded at present as tentative only. Some of tho unusual features of the liqud flow nay possibly be attllbutable to the specific behaviour of tho liquid film, mthout noccssarily inplying the existence of sid.lar flow characteristics in tho 3iT boundary layer itself. An experimental investigation of the aero~amic oharaoterlstios of a tapered wing with 5 leading edge sweptb ek 44' has been carried out in 5 wind. tunnel at e Reynolds number of 0.5 x 1 $9 based on a mean chord of lp in. Chnt-durise pressure distdbutions nt a number VI? spar&se loootions mare measurea over a range of inojdenoe. Consderable attention was given to investignting the boundary layer, quantitative measurements being made with a novel form of yawmeter head, and the flow being studied vi5uaXi.y using ~001 tufts. In addition, a technique for revealdng the direction of flow 5nd form&ion (If vortioes in the layer was developed; this oonsista of sprc\ying the wing with a suspension of kmp-blaok in paraffin with the wind off atd then turning the wind an rapidly. One of the most important results established was the relation of the unstable break in the pitohing moment curve at a mcderate value of overall lift coefficient to the initiation of stalling at the tip region. Another interesting feature was the formetit~n …