Most aircraft generate electrical power via the main engines, which also provide the propulsion thrust. Many aircraft also include an additional turbine engine, known as an auxiliary power unit, which may be used as a backup or supplemental electrical power source, when the aircraft is in flight or on the ground. Some aircraft additionally include a ram air turbine to accommodate the unlikely, yet postulated, complete loss of other power generating sources. Although ram air turbines are most typically found in military aircraft, where such a postulated event may be more likely, many non-military aircraft also include ram air turbines.
A ram air turbine is typically disposed within the aircraft fuselage in a stowed position, and is moved to a deployed position, external of the aircraft fuselage, when needed to supply electrical, hydraulic, and/or pneumatic power. A ram air turbine may include a propeller, or other suitable device, coupled to a generator, a mechanical shaft, and/or other device. When the ram air turbine is moved to the deployed position, ram air flow past the propeller causes the propeller to rotate, which in turn drives the generator, mechanical shaft, and/or other device to supply electrical, hydraulic, and/or pneumatic power.
In some aircraft configurations, one or more turbomachine inlets are in fluid communication with the ram air turbine flow path. Thus, when the ram air turbine is deployed, some ram air flow is supplied to the turbomachine inlet(s). Depending on the flow rate of the ram air to the turbomachine inlet(s), the turbomachine(s) may be driven by the ram air flow in a “windmilling” operational condition. Moreover, in some aircraft configurations, a non-operating turbomachine may receive air flow from sources other than ram air turbine flow path, causing it to be driven in a windmilling operational condition. No matter the particular source of the air flow to the turbomachine(s), the rotational speed of the turbomachine(s) during windmill operation may, in some instances, be sufficiently high that damage could occur if lubrication cooling flow is not supplied to the certain components. Typically, however, when the ram air turbine is deployed various auxiliary systems, such as the turbomachine lubrication supply system, may not be operating.
Hence, there is a need for a system and method of supplying lubrication cooling flow to one or more windmilling turbomachines. The present invention addresses at least this need.