GB858601A - Improved gas generator and method for generating combustion gas under pressure - Google Patents

Abstract

858,601. Generating combustion products under pressure. ROLLS-ROYCE Ltd. Dec. 12, 1958 [Feb. 22, 1958], No. 5817/58. Class 51 (1). [Also in Group XXIX] A gas generator (Fig. 1) comprises a combustion chamber 10 having means 11 for inserting in the chamber a charge of air at supersonic velocity, opposite walls 17, 18 adapted to reflect the charge, inlet means 13, 14 for injecting a charge of combustible mixture into the chamber, and outlet means 15 for allowing a controlled outflow of the products of combustion. Compression ignition of the combustible mixture takes place when the reflected shock wave travelling from right to left impinges upon a portion of the shock wave still travelling from left to right. The detonation wave will then continue to travel to the left and will be reflected at the end 18 thus repeating the process without the necessity of inserting a further charge of air. Connected to the outlet 15 is a tuned filter 16 arranged to reject frequencies in the order of the oscillatory frequency of the shock wave. The mixture inlet valve 14 (Fig. 2) comprises a piston 19 movable in a chamber 20 and attached to a diaphragm 24 forming one wall of a chamber 25 and arranged to oscillate at a frequency equal to that of the shock wave. This frequency is thus imparted by the diaphragm to the piston which uncovers the mixture inlet port 21 allowing the combustible mixture to be injected once during each oscillation of the shock wave. In another embodiment, Fig. 3, combustible mixture is injected through two inlets 32 and 33 into a combustion chamber 27 the inlets being controlled by a rotatable disc 36 having three apertures 38. The disc is rotated by an electric motor 45 set at the oscillatory frequency of the shock wave or may be revolved by turbine blades situated across each of the apertures 38. In operation the charge of air at superonic velocity is injected into the chamber 27 by a device 28 and oscillates at supersonic velocity in the chamber, the difference being that there are now two ignitions per oscillation.