· · · Aerospace Engineering reports

A computer program has been prepared for the determination of the pressure distribution on a thin wing in supersonic flow. The applicability of the program is restricted to cases with completely supersonic trailing edges in the absence of interacting subsonic regions. The present report describes the theory, the numerical evaluation and the computer program and gives some numerical results.

The Coanda effect, being an expedient for the application of blowing boundary layer control^, has been investigated by the NLH to gain an insight into the basic principle and the laws by which it is governed, Within the framework of this investigation a potential theory is developed which, at any rate leads to a qualitative prediction of the increase in volume flow from the slot and the force on the deflecting surface and which will be used as a basis for farther theoretical analysis,

The present report deals with the numerical treatment of the linearised lifting surface theory through a method which is based upon the representation of the pressure distribution on chordwise direction by a series of Chebyshew polynomials according to Laschka, and upon the determination of the spanwise integral involved by means of trigonometric polynomials such as also appUed by Multhopp. When calculations are performed using Multhopp's method the results show strong variations with increasing number of the spanwise stations and chordwise points, to which the boundary condition is applied. This makes it impossible to obtain a plausible solution. Hence a new method has been developed, where the representation of the pressure distribution in spanwise direction is separated from the representation of the regularised kernel function in spanwise direction. This makes it possible to obtain accurate integrals for a given distribution of pivotal points and leads to results which show a rapid decrease of variation as either the number of spanwise stations or the number df chordwise points or both are increased. This is demonstrated by including a number of results for some well-known wings. As the method allows of the possibility to take arbitrary positions for the pivotal points, some computations have been performed for different distributions of spanwise stations. The results indicate that further investigations may be useful.