Enlarging the uniqueness cone of the nine-sensor, T-configuration probe to measure the velocity vector and the velocity gradient tensor

The original concept of a nine-sensor T-configuration hot-wire probe to simultaneously measure three velocity and three vorticity components, as well as other velocity gradient-based turbulence properties, assumes three T-arrays, each with three sensors inclined at 45° to the probe axis. It is shown in this paper that probes having sensors asymmetrically arranged with respect to the probe axis, at specific but different geometrical angles, provide larger angular uniqueness domains in comparison to the original probe. To date it was believed that orthogonal arrays in which three sensors are mounted at 54.74° to the probe axis, as well as their vorticity counterparts, have the largest uniqueness domain of all triple-array-based probes. However, the proposed modified design of the T-array provides uniqueness cone half-angles similar to those that can be achieved by the orthogonal triple-array. In more extreme cases (i.e. at larger departures of the sensor angles from 45°), the uniqueness range of the modified T-array can be made even larger in comparison to the orthogonal array.