On Aerodynamic Disturbances Caused by Single Hot-Wire Probes

Abstract

The disturbances which result from the different parts of single hot-wire probes (stem, prongs, wire sheath if any) are experimentally investigated by means of an auxiliary “reference” probe and are compared with evaluations derived from a potential flow scheme. Our findings suggest that the disturbances created by the prongs are usually 2–4 times greater than that produced by the stem, and that the wire sheath has a negligible effect. The global disturbance, closely equalling the sum of the separate ones, shows up as a velocity decrease when the probe is aligned with the mean flow (8 percent or less depending on the probe’s geometry) and shows up as a velocity increase when the probe is normal to the mean flow (11 percent or less, again depending on the probe’s geometry).