Influence of Anisotropic Thermal Conductivity on Overall Cooling Effectiveness on a Film-Cooled Leading Edge
Carol E. Bryant, James L. Rutledge
Abstract
Abstract Increasing interest in the use of ceramic matrix composites (CMCs) for gas turbine engine hot gas path components requires a thorough examination of the thermal behavior one may expect of such components. Their highly anisotropic thermal conductivity is a substantial departure from traditional metallic components and can influence the temperature distribution in surprising ways. With the ultimate surface temperature dependent on the internal cooling scheme, including cooling from within the film cooling holes themselves, as well as the external film cooling, the relative influence of these contributions to cooling can be affected by the directionality of the thermal conductivity. Conjugate heat transfer computational simulations were performed to evaluate the effect of anisotropy in the leading edge region of a turbine component. The leading edge region is modeled as a fully film-cooled half cylinder with a flat afterbody. Changing the anisotropic directionality of the thermal conductivity is shown to have nearly the same effect on temperature distribution over the surface of the leading edge as increasing the thermal conductivity by a factor of four. While structural considerations with CMC components are often paramount, designers should be aware of the thermal ramifications associated with the selection of the CMC lay-up.