Description

The flow divider plays a crucial role in controlling the ALV10 by demanding signals to maintain proper engine speed and load. The start cycle commences when the start command is issued and the starter begins to rotate the engine. The boost pump and the high-pressure fuel pump, driven from the accessory drive commence to build up fuel pressure. During the beginning the rotation of the engine, the ALV10 is giving a start fuel command [4-20 mA signal]. At low speed (approximately 13-20 percent speed), the ALV10 meters fuel at approximately 160-psig through the flow divider into the single pilot nozzle [P1]. The igniter plug ignites the fuel spraying from the pilot nozzle and the engine begins accelerate. On increasing fuel pressure, at approximately 450-psig, the flow divider admits fuel to the eight primary nozzles [P8]. The ALV10 is commanded to fuel flow demand signal to maintain the proper engine speed and load. As the engine is requesting more fuel from the ALV10 fuel metering valve, the pressure rises to approximately 650-psig. The pressure opens the secondary port [S9] of the flow divider, admitting fuel to the secondary nozzles as required by the turbine. Fuel pressure builds up as engine load increases to the rated load.