Thermal Wave in Thermal Properties Measurements and Flow Diagnostics

The thermal wave technique has been explored for theuse of liquid thermal conductivity measurement andflow property diagnostics in this dissertation. Forliquid thermal conductivity measurements anexperimental technique based on the thermal waveapproach is developed. An aqueous fluid consisting ofgold nanoparticles was tested and anomalous thermalconductivity enhancement was observed. Ourmeasurement results also showed a divergence ofthermal transport behavior between nanofluids andpure liquids. For the study of flow property diagnostics a heattransfer system with a periodic boundary condition ina steady flow field is examined. Due to linearity andhomogeneity of the heat transfer system under certainconditions a thermal wave field generated by aperiodic heating flux at the boundary of the flowfield may be used to detect important flow fieldparameters such as the velocity gradient at thewall and therefore the wall shear stress.