A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - Oblique impact of a jet on a plane surface

Abstract

The dynamics of the region where a jet, striking a plane surface obliquely, is transformed into a thin sheet will be discussed. The maximum (stagnation) pressure is the same for all angles of incidence but the area over which the high pressure acts is much reduced as the angle of incidence, 0 , becomes small. The main transformation from a jet to a sheet is due to a pressure of order sin 2 0 x the jet cross section. The pressure is due to the destruction of the component of velocity normal to the impact surface, but since pressure acts equally in all directions it imparts lateral velocity to streams which are not in the plane of symmetry. Each element of the stream can be regarded as passing through a small region where an impulsive body force changes its direction without changing its velocity, and some properties of this impulse will be described. One case will be given where the transformations from a jet to a thin flat sheet can be described completely and the calculated distribution of pressure in the region where it occurs compared with experimental measurements. Though a jet cannot produce a pressure greater than the stagnation pressure as a steady state, it seems theoretically possible to attain a much higher pressure for a short time when a very oblique jet is moved sideways.