GB1228213A - - Google Patents

Abstract

1,228,213. Ram jet enginesair intakes. ROLLS-ROYCE Ltd. April 16, 1968, No.17760/68. Heading F1J. The invention relates to a system for sensing the position of the terminal shock in a supersonic air intake, there being a plurality of reverse pitot tubes disposed with their inlets spaced apart in a plane transverse to the principal flow axis of the air intake, means for determining a mean of the pressures in the individual pitot tubes, and an operating means having discrete on-off states adapted to change state in response to a change in the axial disposition of the shock, and means responsive to the operating means to act on a parameter of the plant capable of varying the shock portion in the sense of tending to retain it at the critical position. The invention is described with reference to the supersonic intake of a ram jet engine which comprises an outer casing 10 and a centre body 11 which define an annular intake 12. A series of reverse pitot tubes 16 are disposed with their intakes in a common plane 17 normal to the axis 18 of the intake. The normal shock position in the intake is indicated at 15 just downstream of the open ends of the pitot tubes. The pitot tubes are connected to a common chamber 19 so that the mean pressure Pr p of the pitot tubes exists therein, this pressure being compared with a reference pressure P o 1 by means of a piston device, Fig.4 the piston causing one or other of the pairs of contacts 20 to close so moving the piston valve 21 either to the left or to the right, this in turn causing the throttle valve 22 to move either to reduce or increase the fuel supply to the burners 23, the resulting change in combustion chamber pressure causing the shock wave 15 to return to the desired position. The object of the invention is to allow for the possible change in the incidence of the free stream relative to the intake axis.