STUDY THE EFFECT OF AUTOTHROTTLE ON FUEL CONSUMPTION RATE ON TURBOJET ENGINE USING MATLAB

Abstract

Autothrottle (automatic throttle) is a system that automatically manipulates the thrust setting of an aircraft's engines. Used to reduce pilot workload, fuel consumption and also reduce unwanted throttle motion. This thesis is a report on a study of the effect of the autothrottle system on fuel consumption rate in jet engines. There are two modes when implementing autothrottle either engine pressure ratio (EPR) or speed mode. This thesis concentrates on the response of the fuel valve to throttle angle (θ). Block diagram proposed to design a closed loop system single input single output (SISO) to represent an autothrottle using throttle angle (θ) as input and engine R.P.M as output as main variable that will affect the other engine and aircraft variables and forces. MATLAB code had been used to plot system response for different design stages and cases. The combination of PID controllers studied regarding the best performance characteristics (tr, ts, overshoot) to select the best performance and fastest response. Simulation results supported the theory of the relation between autothrottle, airspeed, engine RPM and fuel consumption rate. Estimating the variables for servo and controllers due to lack of data, results in deviation on some readings, that can be solved by working with real engine. Turbofan is suggested for less fuel consumption and adaptive controller is suggested as well.