Aerodynamics for Engineers: III.—Inviscid Flow—Irrotational and Vortex Motion—Aerofoil Lift and Induced Drag
Aircraft Engineering and Aerospace Technology
ISSN: 0002-2667
Article publication date: 1 December 1930
Abstract
WE found, on experimental grounds in Article I, that the field of air‐flow past a short body of low resistance shape, such as an aerofoil, comprises two dissimilar parts: (a) a thin boundary layer enveloping the body and dominated by viscous effects, and (b) a motion outside the boundary layer in which viscosity is much less important. It will be remembered that in the external motion occur the large pressure changes, which, transmitted through the boundary layer, account for nearly all the lift and for part of the drag. These pressures we observed to be calculable from the velocities without appreciable error by Bernoulli's equation. In the present Article we confine attention to this external flow, assuming it to be steady, incompressible, and inviscid. Its dependence upon (a), already discussed to some extent, we ignore; the boundary layer is conceived to be everywhere very thin, so that the only role it plays is to allow of relative velocity at the surface of the body. The assumptions made, excepting that of incompressibility, will appear drastic, and it will not be surprising if some of our deductions prove discordant with experimental fact. Nevertheless, they lead to a theory which finds many applications and uses in real fluid motion, and, in particular, gives an intimate view of aerofoil flow that is very close to the truth. It is convenient to develop our reasoning in analytical terms and for simplicity to restrict the flow to two dimensions (Article 1, §5). But the engineer will find special scope in this part of aerodynamics for graphical methods in the solution of particular problems.
Citation
Piercy, N.A.V. (1930), "Aerodynamics for Engineers: III.—Inviscid Flow—Irrotational and Vortex Motion—Aerofoil Lift and Induced Drag", Aircraft Engineering and Aerospace Technology, Vol. 2 No. 12, pp. 311-314. https://doi.org/10.1108/eb029349
Publisher
:MCB UP Ltd
Copyright © 1930, MCB UP Limited