GB899681A - Improvements relating to the control of the ratio of the flow rates of fuel and oxidant to a combustion chamber - Google Patents

Abstract

899,681. Rocket propulsion. BRISTOL SIDDELEY ENGINES Ltd. April 28, 1960 [May 1, 1959], No. 14883/59. Class 110 (3). [Also in Group XXIX] Apparatus for controlling the flow ratio of oxidant and of fuel to a combustion chamber, such as in a rocket motor, comprises flow pipes 3, 4 for leading oxidant and a fuel respectively to the combustion chamber, means 1, 2 in each pipe capable of producing a pressure difference in response to flow therethrough, separate pressure tappings leading from each of the flow paths at a position upstream of the means therein and at a position of reduced pressure produced by the means, a valve-actuating device 9 responsive differentially to the pressure difference for use by each of the means and a valve 7 operable by the valve-actuating device to vary the rate of flow through one of the pipes with respect to the flow through the other pipe, whereby the flow ratio can be maintained substantially constant, the valve-actuating device comprising a housing 12 defining a pair of separate compartments in which pistons 10, 11 are mounted, and a rod 8 connecting at least one of the pistons with the valve. The means 1, 2 as shown in Fig. 1, are in the form of Venturi meters, the opposite sides of the piston 10 being connected by pipes 15, 19 into the Venturi-meter 1, and opposite sides of the piston 11, being connected to the Venturi-meter 2 by a pipe 20 and a connection upstream of the latter meter. The pistons are connected by a common rod 8 which is coupled to a valve 7 located in the fuel pipe 4. In operation, if a variation in flow occurs in the oxidant pipe 3, the pressure difference thereby produced across the Venturi-meter 1 moves the piston 10 and thus adjusts the position of the valve in order to permit more or less fuel through the pipe 4. The flow through the Venturi 1 is initially set by a by-pass 5, 6; alternatively, Venturi-meter 2 may be provided with the by-pass. In a modification, the Venturi-meters, which have fixed throats, may be provided with a spring- loaded throttling device which produces a varying flow characteristic through the Venturi.