Measurement of small-scale turbulence structure with hot wires

Abstract

Expressions are derived for turbulence spectra measured with a single hot wire and wires in an X-array, and are applied to the problem of measurement of spectra at small scales. Isotropic turbulence and Pao's form for the three-dimensional spectrum are assumed. Calculated curves for one-dimensional spectra measured with a single wire and an X-array are presented. Experimental data in good agreement with the single wire calculations are shown. The calculations show that both one-dimensional spectra measured with the X-array are contaminated by crosstalk from the other component. The effect is more serious for the longitudinal spectrum and depends on array geometry and the Kolmogorov microscale.