GB842286A - Improvements in or relating to aviation jet propulsion engines - Google Patents

Abstract

842,286. Automatic control systems for gas turbines. SHEPHERD, G. R. (Westinghouse Electric International Co.). March 28, 1958, No. 10026/58. Class 38 (4). [Also in Group XXVI] In a gas turbine jet-propulsion plant in which additional fuel is burnt in the turbine exhaust gases before entering the propulsion nozzle, the additional fuel is controlled by primary control means combined with secondary control means including a valve which modifies the fuel flow in response to changes in the temperature drop between the temperatures just upstream and just downstream of the additional fuel injecting means. A gas turbine jet-propulsion engine 10 has an after-burner or reheat chamber 20 to which fuel is supplied by nozzles 27 attached to fuel manifolds 25, 26. A flame-holder 28 is provided downstream of the nozzles 27. The fuel supply to the nozzles 27 is controlled by a unit 33 which, as shown, meters the fuel supply in response to changes of compressor discharge pressure but which may be any engine operating condition. A by-pass conduit 36 has a control valve 37 which is regulated by a control unit 41 in response to the difference in temperature between the temperature-sensitive elements 39, 40. The element 40 detects the temperature of the turbine exhaust gases before they are modified in the after-burner and is arranged in the gas flow before the manifolds 25, 26. The element 39 is disposed between the fuel nozzles 27 and flame-holder 28 and the exact position is not critical but it should be sufficiently spaced from the nozzles 27 to ensure that substantially all the fuel is vaporized. In a typical arrangement the element is spaced 10 to 20 inches downstream of the nozzles 27. In a modification, Fig. 2 (not shown), the primary fuel is controlled so as to maintain the turbine exhaust gas temperature constant. The by-pass valve is then only controlled by the temperaturesensitive element 39.