Estimation of internal and external heat loads by inverse conduction analysis of internally-cooled turbine vane

Quantifying the cooling performance of real hardware, internally-cooled gas turbine parts is challenging due to their characteristic dimensions and thermal properties and to the limited instrumentation access to their internal, cooled surfaces. Inverse heat conduction analysis methods are used in this context to estimate the heat loads generated by an internal cooling system from measurements of the resulting external surface temperature distribution of the cooled part. Existing works in the turbine cooling literature rely on bench-top testing facilities that do not reproduce a relevant external aero-thermal load, thus limiting the types of cooled components that may be tested with realistic internal flow behavior. The objective of this study is to extend traditional inverse conduction analysis and to demonstrate experimental and numerical methods to estimate the internal cooling performance of a real hardware-like nozzle-guide vane operating with engine-representative internal and external thermal loads. Thermal transient tests conducted with the test article installed in a linear cascade wind tunnel generate the external surface temperature responses necessary for the proposed iterative post-processing procedure to estimate both the internal and external heat loads. In particular, this work focuses on the description of the experimental test procedures developed and of the numerical post-processing approach. Internal and external heat load estimates are presented for a series of test conditions defined by combinations of different cooling system Reynolds numbers and the tunnel’s mainstream turbulence intensity. The results demonstrated it was possible to reproduce reference results with an acceptable accuracy within an evaluated experimental uncertainty of approximately 20%, suggesting the possibility of studying more complex and realistic test cases.