Hydraulic Fuel System Simulation Using Newton-Raphson Method and its Integration with a Gas Turbine Performance Model

A fuel system in a gas turbine engine is to meter and deliver required fuel flow to the engine in order to power its operation. A hydraulic fuel system may consist of pumps, valves and metering unit. The fuel has to be sucked from a reservoir, pressurized by the pumps, and regulated by the valves before being injected into an engine combustion chamber. A slight delay of fuel system component response may result in noticeable impact on the engine transient performance response. In this paper, a novel method for engine hydraulic fuel system performance prediction based on Newton-Raphson approach has been introduced. A gas turbine transient performance simulation system has been set up, where gas turbines are simulated with an inter-component volume method, control systems are simulated with a proportional-integral (PI) controller and hydraulic fuel systems are simulated with a new fuel system model based on Newton-Raphson method introduced in this paper. The developed performance simulation system has been applied to a model one-spool aero gas turbine engine similar to Rolls-Royce AVON. A typical transient process of the model engine has been simulated to investigate the effectiveness of the introduced fuel system simulation method and the coupling effect between the gas turbine and the fuel system. Results show that the inclusion of a fuel system model will result in a noticeable delay in engine transient behaviour compared with that without the inclusion of the fuel system model although such delay is relatively small. Such modelling method can help set up physics-based fuel system models and analyse the detailed behaviour and mechanism of the fuel systems during engine transient processes. This may provide very useful information to assist the understanding of engine performance behaviour and support the designs of engines, control systems or fuel systems. Such method is generic and can be applied to different hydraulic fuel systems.