oa Development of an optimal data reduction scheme fora four-wire hot-wire probe

One of the most widely used measurement instruments in the turbulence community is the hot-wire probe. Amongst them, the four-wire probe is lately gaining popularity because of the enhanced accuracy and the extended directional working range due to the presence of the fourth ‘redundant’ wire. However, the need for exhaustive calibration makes the hot-wire probe a less preferred instrument to be used in atmospheric research. In the present study, development and testing of an effective data reduction scheme for a four-wire probe is reported. The robustness of the data reduction scheme enables one to obtain the same order of accuracy in measurement with reduced calibration points, and in turn reduced calibration effort. The data reduction scheme works based on the calculation of the directional sensitivity function of each wire, and then, minimization of an artificially constructed error function. Since the directional sensitivity function is smooth and continuous in space, the same order of accuracy can be obtained with less effort. In the present work, a four-wire probe was considered, and calibrated in a constant velocity jet facility. Following calibration, the data reduction scheme was applied to test the probe numerically for a random noise applied on four probes simultaneously, and the angular error was computed. The assessment of the involved accuracy of the data reduction scheme with reduced points of calibration was established.