turboprop engines Control Systems
The main objectives of turboprop management are:
- control of the thrust of the propeller (propeller-fan) by changing the power of the gas generator, the angles of the blades and the rotational speed of the propellers with the best efficiency;
- ensuring the best efficiency of the control system by coordinating the operating modes of the gas generator and the propeller in accordance with the aircraft flight conditions;
- reduction of the noise level generated by propellers by means of propeller synchrophasing and changing their rotation frequency;
- ensuring the safe operation of the engine in case of damage to its components and failures in the ACS;
- control of the reverse of the thrust of the propellers when landing the aircraft and taxiing at the airport;
- protection of the engine during surge and automatic elimination of compressor surge;
- automatic restoration of the engine operating mode when the combustion chamber goes out.
Automatic control systems turboprop engines perform the following functions:
- engine start control on the ground and in flight;
- control of engine power or propeller thrust in flight and on the ground; control of the engine in transient modes of operation when changing its power, reverse thrust and parrying disturbances;
- limiting the limiting values of engine parameters (power, torque, rotational speed of the gas generator and propeller rotors, gas temperature) in order to protect it from overheating or destruction;
- control of compressor mechanization bodies, turbine cooling;
- optimization of the rotational speed of the propellers for flight conditions;
- synchrophasing of screws;
- self-control of the system and compensation of failures of its elements.
In many modern SAU one electronic device
integrated automatic control functions and operational control of a technical condition of the engine.
Possible errors in the control of ACS turboprop engines are:
- maintenance (limitation) of power or torque ± 2%;
- maintenance (limitation) of the gas generator rotation frequency ± 0,15%;
- limitation of the reduced frequency of the gas generator ± 0,3%;
- maintaining (limiting) the propeller speed ± 0,5%;
- limitation of gas temperature ± 6. 10 ° C;
- limiting fuel consumption ± 5%.
Tolerances motor parameters in transient modes have the following meanings:
- overshoot of the frequency of rotation of the gas generator Дпгг <1%;
- overshoot of gas temperature <15 ° С;
- overshoot of power, torque <4%;
- overshoot of the rotor speed <4%.