BACKGROUND

This disclosure relates to an air valve system and more particularly a fueldraulic air valve system.

A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. Air moves into the engine through the fan section. Airfoil arrays in the compressor section rotate to compress the air, which is then mixed with fuel and combusted in the combustor section. The products of combustion are expanded to rotatably drive airfoil arrays in the turbine section. Rotating the airfoil arrays in the turbine section drives rotation of the fan and compressor sections. The compressor section and turbine section each have multiple stages of blades that rotate about a central axis and multiple stages of vanes that are stationary relative to the central axis.

Some gas turbine engines have air valves for bleed air. Bleed air may be used in the engine such as for starting, low power stability, and stall recovery, for example.

SUMMARY

In one exemplary embodiment, a valve assembly for a turbine engine includes a valve arranged in an air flow path. The valve has a shaft. The valve is movable between an open position and a closed position. A hydraulic actuator is coupled to the shaft. The hydraulic actuator is configured to utilize fuel as a working fluid. The hydraulic actuator is configured to move the valve between the open position and the closed position.

In a further embodiment of any of the above, the valve is a poppet valve.

In a further embodiment of any of the above, the air flow path is configured to have a temperature of greater than about 1000° F. (537.8° C.).

In a further embodiment of any of the above, the hydraulic actuator is configured to move the valve to an infinite number of positions between the open position and the closed position.

In a further embodiment of any of the above, the valve is formed from metallic components.

In a further embodiment of any of the above, a thermal barrier is arranged between the valve and the hydraulic actuator.

In a further embodiment of any of the above, cooling fins are arranged on the shaft.

In a further embodiment of any of the above, a linear variable displacement transformer is arranged on the shaft.

In a further embodiment of any of the above, the shaft comprises a first shaft portion that is attached to the valve and a second shaft portion attached to the actuator. A thermal barrier is arranged between the first and second shaft portions.

In a further embodiment of any of the above, an actuator housing defines a cavity about the shaft. A cooling port extends through the housing to permit ambient air to flow into the cavity.

In a further embodiment of any of the above, a second cavity is defined within the shaft. A second cooling port extends through the shaft to permit ambient air to flow into the second cavity.

In a further embodiment of any of the above, a plurality of seals are arranged between the hydraulic actuator and the valve.

In a further embodiment of any of the above, the actuator housing includes a port configured to communicate fuel around the plurality of seals.

In another exemplary embodiment, a turbine engine includes a compressor configured to deliver air to a combustor. A valve assembly has a valve arranged in an air flow path. The valve has a shaft. The valve is movable between an open position and a closed position. A hydraulic actuator is coupled to the shaft. The hydraulic actuator is configured to utilize fuel as a working fluid. The hydraulic actuator is configured to move the valve between the open position and the closed position.

In a further embodiment of any of the above, the air flow path receives bleed air from the compressor.

In a further embodiment of any of the above, the fuel is delivered to the fuel return downstream of the hydraulic actuator.

In a further embodiment of any of the above, a thermal barrier is arranged between the valve and the hydraulic actuator.

In a further embodiment of any of the above, the shaft comprises a first shaft portion that is attached to the valve and a second shaft portion attached to the actuator. A thermal barrier is arranged between the first and second shaft portions.

In a further embodiment of any of the above the hydraulic actuator is configured to move the valve to an infinite number of positions between the open position and the closed position.

In a further embodiment of any of the above an actuator housing defines a cavity about the shaft. A cooling port extends through the housing to permit ambient air to flow into the cavity.

