The reflection effect of fences at low speeds

Abstract

This note considers the effect on the flow over a swept wing, of vertical plates of small height--commonly called 'fences'. It is shown, as might be expected, that the nature of this effect is that of a partial-reflection plate. The effect of this partial reflection on the pressure distribution over the wing on either side of the fence has been investigated theoretically and by means of pressure measurements at low speeds on an untapered 45 deg swept-back wing. An earlier physical explanation 1 of the flow changes caused by fences has been substantiated, and the proportion of full reflection effect has been determined experimentally for various shapes of fence. Methods are described for calculating the changes in pressures distribution, chordwise loading and spanwise loading. The effect of a fence in obstructing boundary-layer outflow on swept-back wings of large aspect ratio has not been considered.