A hot-wire probe configuration and data reduction method to minimize velocity gradient errors for simultaneous measurement of three velocity components in turbulent flows

摘要

A highly resolved turbulent channel flow direct numerical simulation (DNS) with Re τ = 200 has been used to investigate the influence of the velocity gradients on the measurement accuracy of a hot-wire probe capable of measuring all three velocity components simultaneously. A new proposed sensor arrangement has been tested. First, the effective cooling velocity was determined for each sensor of the idealized probe, where the influence of the velocity component tangential to the sensors and flow blockage by the presence of the probe are neglected. Then, velocity component statistics were calculated, neglecting the velocity gradients over the probe sensing area, and they were compared to the DNS database values. It has been shown that the influence of the velocity gradients on the new proposed arrangement is minimized. Its accuracy was compared to existing three- and four-sensor configurations as well as to two-sensor X- and V-array probes.