Constant Voltage Anemometer Practice in Supersonic Flows

Abstract

It is shown that the constant voltage anemometer (CVA) is well adapted for measurements in supersonic flows. Small hot-wire time constant, large bandwidth, high signal-to-noise ratio, variable hot-wire overheat, and independence of the cable capacitance effects of the hot wire were all observed with the CVA. Turbulence data were acquired using two methods. In the first method, signals were acquired with the CVA compensated with a fixed time constant of 0.10 ms at all test points. In situ hot-wire time constant and overheat were also acquired at each test point, which were then used in postprocessing of the turbulence signals. In the second method, full hardware compensation with the actual in situ time constant was set at each test point. The former method shows a larger bandwidth. The noise level was approximately the same in both methods. Theoretical estimates of the relative output levels of CVA, constant current anemometer, and constant temperature anemometer at different overheat ratios show that the CVA has larger output voltage level