Hydro-mechanical fuel flow controller for aircraft jet engines

The paper deals with a fuel flow rate controller (fuel control unit-FCU) with indirect action for aircraft jet engines, based on fuel pressure drop's control. The author identifies system's main parts, its operation mode and main parameters. Based on these observations one has determined main parts' motion equations and has built the non-linear mathematical model; meanwhile, main input and output parameters were identified. Controller's mathematical model was linearised, using the finite differences method, then adimensionalized and brought to a usable form by applying the Laplace transformation; system's block diagram with transfer functions was also built. Based on it, some Simulink-Matlab simulations were performed, in order to establish system's quality (controller's time behavior for step input(s)), which led to some useful conclusions regarding controller's operation mode, as well as regarding the possibilities of controller's embedding into new control architectures.