Gas Turbine Engine Fuel System PDF

MODULE 15 GAS TURBINE ENGINE FUEL SYSTEM TAHA AL FALAHI  Table Of Contents 1. INTRODUCTION 2. FUEL SYSTEM SUBCATEGORY 3. MAIN FUNCTIONS OF THE ENGINE FUEL SYSTEM 4. ENGINE FUEL SYSTEM FIGURE 5. ENGINE PROTECTION 6. FADEC SYSTEM  INTRODUC...

MODULE 15 GAS TURBINE ENGINE FUEL SYSTEM TAHA AL FALAHI  Table Of Contents 1. INTRODUCTION 2. FUEL SYSTEM SUBCATEGORY 3. MAIN FUNCTIONS OF THE ENGINE FUEL SYSTEM 4. ENGINE FUEL SYSTEM FIGURE 5. ENGINE PROTECTION 6. FADEC SYSTEM  INTRODUCTION  There are many systems required for an aircraft to operate smoothly and efficiently, one system mainly which is the Engine Fuel System and is the highlight of our discussion.  The Engine Fuel System must be available to the engine under all circumstances of engine power. FUEL SYSTEM COMPONENT LOCATION  The primary components of the fuel system are installed on the LH side of the fan compartment.  The fuel pump is operated by the gearbox.  The Hydro-Mechanical Unit (HMU) and the filter are installed with the pump  FUEL SYSTEM PRIMARY FUEL SYSTEM SECONDARY FUEL SYSTEM AIRFRAME ENGINE  THREE MAIN FUNCTIONS OF THE ENGINE FUEL SYSTEM FUNCTION ONE: Sustain combustion in the combustion chamber to provide thrust in all operation of the engine WHAT DOES IT MEAN? The engine fuel system is designed to supply fuel flow (FF) into the combustion chamber from the main tanks through the LP valve driven by LP pump. It is heated by the main oil/fuel heat exchanger, filtered, then pressurized by the HP pump before entering the hydromechanical unit (HMU) or fuel control unit (FCU). In HMU or FCU, the fuel from the HP fuel pump goes through a fuel metering valve (FMV) which allows only metered fuel pass to the nozzle into the combustion chamber. FUNCTION TWO: Servo fuel ( pressurized fuel) acts as a muscle to actuate the compressor airflow control, turbine clearance control and fuel metering valve. WHAT DOES IT MEAN? After the HP pump the fuel goes through the wash screen filter and the servo fuel heater to make sure that ice particles is cleared entering the servo valves. The servo valves in HMU are hydraulically driven by torque motor controlled by ECU to provide the operation of the actuators like : 1. Transient bleed valve (TBV) 4. Low pressure turbine active clearance control (LPTACC) 2. Variable stator valve (VSV) 5. High pressure turbine active clearance control (HPTACC) 3. Variable bleed valve (VBV) 6. Fuel metering valve (FMV) FUNCTION THREE Heat management system Engine oil cooling through the oil/ fuel heat exchanger. Integrated Drive Generator oil cooling through the IDG oil cooler. Servo fuel heater IDG oil cooling The fuel bypass valve from the HMU and returned servo fuel used to cool the IDG oil through the IDG cooler. Fuel return valve (FRV) The FRV is electrically controlled by the ECU and hydraulically operated by servo fuel Engine oil and IDG oil gets too hot then the FRV will allow some hot fuel to return to the aircraft tanks The FRV mixes cold fuel from the LP pump with hot return fuel to reduce thermal stresses  ENGINE PROTECTION OVERSPEED:  Overspeed protection is performed by governor that works mechanically through a flywheel and by-pass valve.  This system is independent from FADEC.  In case of overspeed, flywheel movement will cause by-pass valve to open, and consequently, part of fuel will be recirculated instead of supplied to combustion chamber.  The only relation to FADEC is in the form of switch, which will send signal to FADEC if N2 is more than 45%.  It will inform that overspeed protection is active EMERGENCY SHUTDOWN: In case of emergency, the fire push button is pressed to confirm the closure of the LP shutoff valve following the shutdown of the engine. HIGH PRESSURE SHUT OFF VALVE: This is used to supply or cut off the fuel to the combustion chamber. It is activated by the pilots and operated by fuel pressure. NORMAL SHUTDOWN: When the engine master switch is set to OFF, the LP and HP fuel shutoff valve (LP/HP SOV) are closed as well as the fuel return valve (FRV). The FRV is driven closed by the ECU.  FADEC GENERAL  The Full Authority Digital Engine (FADEC) provides the regulation and scheduling of the engine systems to control the thrust and optimize engine operation.  FADEC also interfaces with aircraft signals.  The FADEC system of each engine consists of a dual channel ELECTRONIC CONTROL UNIT (ECU).  The ECU is the computer of FADEC and is located on the engine fan case.( Right Hand Side). POWER SUPPLY  Each ECU is powered by a three-phase permanent magnet alternator when the engine N2>15%.  The FADEC control alternator provides an independent power supply to both ECU channels. FADEC FUNCTIONS The FADEC system performs engine control functions which includes: 1. Power management control 2. Variable Bleed Valves (VBVs) control 3. Variable Stator Vanes (VSVs) control 4. Transient Bleed Valve (TBV) control 5. Fuel control regulation 6. High Pressure Turbine Active Clearance Control (HPTACC) 7. Low Pressure Turbine Active Clearance Control (LPTACC) 8. Fuel Return Valve (FRV) control 9. Indications ANY QUESTIONS ? THANK YOU!