Note on the evaluation of solid-blockage corrections for rectangular wind tunnels with slotted walls

Abstract

During the preparation at the N.P.L. of a manual of tunnel interference the necessity arose for calculating additional values of the blockage-interference corrections for small bodies in incompressible flow in rectangular tunnels having longitudinally slotted roofs and floors. This consisted essentially of extending the work of Davis and Moore to include a wider range of tunnel height/breadth ratio. In order to do this without excessive computation it was necessary to simplify the formulae given in Ref. 1, and this report is concerned with the manner of simplification and with the results of the calculations.