Publications

Description

Authors: Paula Murphy, Tim Persoons, Seamus O’Shaughnessy

Abstract: The use of hot film sensors as a means of heat flux measurement has been shown to possess superior accuracy when compared to some traditional methods due to its enhanced spatial and temporal resolution. A localised temperature elevation is introduced as a result of the required sensor overheat however, which can lead to a distortion or bias in the measured results. This study aimed to compare the effectiveness of various post-processing techniques previously developed to remove such bias from the hot film data, while also optimising the sensor overheat value when used to evaluate the heat transfer behaviour associated with impinging jet flows. Three hot film post-processing techniques were chosen for this investigation: (A) a wall shear correction method, (B) a physical quasi 1-D conduction model and (C) a physical quasi 2-D fin conduction model. Experimental data was collected for an axisymmetric impinging air jet ejected from a long pipe nozzle. Airflow Reynolds numbers of  and  were examined for a constant jet height , where sensor overheat values of , ,  and  were investigated for the first jet configuration and  and  for the latter. The use of an RdF Micro-Foil® heat flux sensor provided the reference against which the performance of each method could be compared, which revealed Method C with a  sensor overheat to be the most accurate predictor of the surface heat flux.