lm2500_hydstrter

Hydraulic Starter

The hydraulic starter available to the Purchaser as an option is described on Figure 1. It consists of a variable-displacement type hydraulic motor with piston stroke controlled by a wobble plate. Displacement is controlled by varying the angle of the wobble plate by means of a pressure compensator. The starter is equipped with an overrunning clutch to prevent the starter from being driven by the gas generator when the hydraulic supply pressure and flow are reduced to zero and the gas generator speed is greater than that of the starter. Starting time to gas generator idle speed, using the hydraulic starter, is in the range of 60 to 90 seconds.

The hydraulic supply and control system for the starter is to be supplied by the Purchaser. Figure 2 is a flow diagram of a typical Purchaser-supplied system. The hydraulic supply and control system for the starter is supplied by the Purchaser. Figure C6 provides a schematic of a typical Purchaser-supplied system. The starter requires a flow capability of 0 to 55 gpm minimum of hydraulic fluid at a pressure differential of 4150 psi. A list of the starter manufacturer’s approved oil types is found in DEB-101.Recommended starter inlet pressure (pump compensator pressure) is 4300-4350 psig. Maximum allowable transient starter inlet pressure 5300 psig. (5300 psig is a maximum value and that starter life is extended by maintaining the starter inlet pressure at 4300-4350 psig.) Maximum allowable starter discharge pressure 300 psig. The oil temperature shall be between 32° and 200°F and the oil shall be filtered to 10 µm.

Figure 1. Hydraulic Starter.

Page 1 of 3Operation

19/11/2005http://inside-aep.ps.ge.com/insideaep/aep/iad/engine_prod_delv/idms/common/chydstarte...

Figure 2. Typical Hydraulic Starter Schematic.

Required starter output torque, as a function of speed, is a function of ambient temperature, lube oil viscosity, accessory gearbox pad usage, and desired time to idle. Figure 3 describes the performance of the hydraulic starter.

It is recommended that the starter not be engaged unless the gas generator is at rest. If necessary, engagement can be made at normal windmilling speeds not to exceed 300 rpm. Engagement of the starter at gas generator speeds exceeding 300 rpm is lokely to damage the starter or accessory gearbox drive system.



Figure C-10. Hydraulic Starter Performance.

The oil supply pressure shall be reduced to 0 psig after the gas turbine reaches 4000 to 4500 rpm. Drive input power for the hydraulic supply pump will be approximately 180 to 200 horsepower, depending on Purchaser’s selection of pump and operating pressure.

The maximum flow through the starter case drain is 1.5 gpm. A minimum positive back pressure of 0.1 psig should be maintained on the starter case drain to ensure a proper oil level within the starter cavity during operation. It is recommended that this be accomplished by mounting the hydraulic oil tank above the installation elevation of the starter. The maximum allowable back pressure on the starter case drain is 25 psig.

It is recommended that a circulating system be used that is connected across the case drain interfaces shown in Figure 1 to maintain a flooded case and ensure lubrication to the clutch in the overrunning mode. A circulating flow of 2 gpm is recommended with the case protected by a relief valve set at 25 psig. Filtration to 10 mm nominal is required for this system also, and it uses the same fluid as the main supply and return loop.

The maximum flow from the overboard seal drain is 5 cm3/hour and the maximum back pressure is 1 psig. There are no duty cycle limits on this starter provided the supply temperature is maintained under 140°F.



Documents

lm2500_hydstrter