Experimental study on hot-wire spatial resolution in turbulent round jet

Hot-wire spatial-resolution effects are investigated in a round jet, using custom-made probes with Platinum wires of 5 and 2.5 μmof diameter. Characteristic turbulent scales are varied by both moving the probes along the jet centerline (10 < x/D < 30), and using two different nozzle diameters at a constant Reynolds number of ReD = 7 × 104. The variance of spatial derivatives shows an attenuation of one order of magnitude greater than the velocity variance, i.e. 10-30% compared to 1-2%. Power spectra show this attenuation to be located at high frequencies, in agreement with the hypothesis of spatial-filtering effect.