Paper 12: Gas Turbine Fuel and Control Systems

Abstract

Following a preliminary introduction on the necessity for fuel and control systems, it is proposed to deal in some detail with the requirements of modern gas turbine engines from the point of view of both pumping of fuel and the control. In general the paper deals with aircraft type systems. Over the last 20 years specifications have been increasing in size and the need for the additional requirements will be discussed in relation to the various types of engines. Considerations of control for two- and three-shaft engines for both civil (subsonic and supersonic) and military use are covered, as also are the somewhat different requirements for helicopters. In addition to main engine control, the effects of reheat, supersonic nozzles and variable engine geometry will be discussed. Reference is also made to the increasing severity of environment on high speed aircraft. Following this, the problems of pumping are considered and a review of the types of pumps available is made comparing their relative advantages and disadvantages in relation to the application, and indicating the general trends in this field. On control systems the types of control available will be discussed including hydromechanical, electric and fluidic, and the basis on which the optimum choice can be made for any particular engine will be dealt with. The requirements for control, both for steady running and limiting will be explained, and once again a typical example of a control system is briefly described.