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.
