A gas turbine engine generally includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air enters an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel mixes with the compressed air and burns within the combustion section, thereby creating combustion gases. The combustion gases flow from the combustion section through a hot gas path defined within the turbine section and then exit the turbine section via the exhaust section.
The turbine section includes one or more rows of turbine nozzles, which direct the flow of combustion gases onto one or more rows of turbine rotor blades. The turbine blades, in turn, extract kinetic energy from the combustion gases. These nozzles generally operate in extremely high temperature environments. As such, the nozzles may be constructed from a ceramic matrix composite (“CMC”) or other suitable material capable of withstanding the high temperature exhaust gases.
The CMC turbine nozzles in each row generally must be coupled together to form an annular arrangement thereof. Nevertheless, metallic fasteners are unsuitable for coupling each the CMC turbine nozzles to each adjacent turbine nozzle at high temperatures. More specifically, metallic materials have a greater coefficient of thermal expansion than CMC materials. In this respect, the metallic fasteners expand at a greater rate than the CMC turbine nozzles. As such, the metallic fasteners may outgrow the CMC nozzles, thereby providing less clamping force to couple the turbine nozzles at high temperatures. This could allow combustion gases to escape between the turbine nozzle segments, which could reduce the efficiency of the gas turbine. Accordingly, a clamping assembly that maintains or increases clamping force at higher temperatures would be welcomed in the technology.
USPTO Backgrounds
USPTO Backgrounds