A turbofan gas turbine engine may be used to power aircraft and may include, for example, a fan section, a compressor section, a combustor section, a turbine section, and an exhaust section, where each section has components that are mounted to a rotor. The fan section induces air from the surrounding environment into the engine and accelerates a fraction of the air toward the compressor section. The remaining fraction of air is accelerated into and through a bypass plenum, and out the exhaust section.
The compressor section, which may include a high pressure compressor and a low pressure compressor, raises the pressure of the air it receives from the fan section to a relatively high level. The compressed air then enters the combustor section, where a ring of fuel nozzles injects a steady stream of fuel into a plenum. The injected fuel is ignited to produce high-energy compressed air. The air then flows into and through the turbine section causing turbine blades therein to rotate and generate energy. This energy is used to power the fan and compressor sections. The air exiting the turbine section is exhausted from the engine via the exhaust section, and the energy remaining in the exhaust air aids the thrust generated by the air flowing through the bypass plenum.
To support the rotor during engine operation, bearing assemblies may be mounted to a forward section of the rotor and/or an aft section of the rotor. The bearing assemblies are typically kept cool with a bearing lubrication system that lubricates components of the bearing assemblies. Many configurations include a tube that fluidly communicates with an oil source for continuous direction of a lubricant, such as oil, over the bearings. However, bearing assemblies mounted to the aft section of the rotor may be subjected to relatively high operating temperatures. These high temperatures may cause carbonization of the lubricants, also known as coke formation or “coking”, which may exasperate heat generation and heat retention. Over time, deposited coke may undesirably decrease the useful life of a lubricated bearing system.
In the past, heat shielding mechanisms have been employed to reduce the incidence of coking. For example, mechanisms such as insulation blankets have been wrapped around a bearing carrier of the bearing assembly to protect the assembly components from the high temperatures. However, as engine operating temperatures have continued to increase above 535° C. (1000° F.) due to the desire for increased engine efficiency, the effectiveness of insulation blankets in hot sections of the engine, such as in the exhaust section, has decreased.
Accordingly, it is desirable to have a bearing assembly cooling system that provides improved protection from high temperatures over conventional heat shield mechanisms. In addition, it is desirable to have a bearing assembly cooling system that is relatively simple and inexpensive to implement and that imposes very little to no weight or power loss penalty on the engine. Moreover, it is desirable for the bearing assembly cooling system to be suitable for retrofit into existing engines. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.