Boundary Conditions for Ceramic Turbine Components: Analytical Prediction and Test Validation

Abstract

Ceramics allow gas turbine engines to run at higher temperatures to increase power and efficiency. Ceramic component development is therefore required to understand transient thermal behavior and temperature distributions. As a part of contract with US Department of Energy (DOE), a series of finite element analyses were completed and a Solar Turbine (Solar) Centaur 50S engine was tested to characterize this behavior. To better understand the interaction between the metallic and ceramic components during engine operation, a finite element model was prepared. The boundary conditions for this model were estimated analytically or using existing test data. To verify the boundary conditions in the vicinity of uncooled ceramic components, two engine tests were performed on a metallic engine simulating the ceramic engine configuration. The Solar Centaur 50S engine normally operates at 1010°C with all metallic components. A Centaur 50S eagine was retrofitted with a ceramic combustor liner and uncooled first stage turbine blades and nozzles. Two tests were conducted at firing temperatures of 1095 and 980°C. Using metallic components saved time, reduced the complexity of working with ceramic components, and eliminated some of the difficulties of attaching instrumentation to ceramic parts. Component temperatures were measured and used in the finite element analyses to help predict blade tip clearances, ceramic component temperatures, stresses and ultimately component lives. The strategy undertaken and results presented herein provided a reliable and effective approach to ceramic component development and provides critical temperature information in the qualification process for ceramic gas turbines.