A Simple Corner Correction Technique for Transient Thermal Measurement

The 1D conduction analytical and semi-analytical approaches for a semi-infinite domain have been widely adopted in the data processing of transient thermal experiments. The convective heat transfer coefficient (HTC) calculated by the 1D approach contains large errors when lateral conduction effects are significant, especially near a corner of solid domain. The problems could be addressed by alternative full 3D numerical conduction analyses, which tend to be complex as well as requiring extra experimental efforts to obtain the full thermal boundary conditions around corners, in addition to an access to a 3D conduction solver (CFD or FEA). In the present work, a simple and effective method is developed to correct such errors in the near-corner region without using any commercial tool. The present approach is based on the recognition that a temperature time trace in a 2D situation is the result of the accumulated heat conductions from the normal and lateral directions respectively and summatively. An equivalent semi-infinite 1D conduction temperature trace for a correct HTC can be generated by reconstructing and removing the lateral conduction effect at each discrete time step. This simple new correction procedure enables the standard 1D conduction analysis to be properly used to get the correct HTC, completely analytically without needing any aid of CFD or FEA solutions. Two test cases of practical interest with turbine blade tip heat transfer and film cooling are used for validation and demonstration. It has been consistently shown that the errors of the conventional 1D conduction analysis in the near corner regions can be greatly reduced by the new corner correction method. The demonstrated validity, the simplicity and robustness of the present method makes it a good candidate for future applications in transient thermal experimental studies.