Determination of hot-film constant-temperature-anemometer response

Abstract

Improvements in electronic and theoretical techniques for determining Constant-Temperature-Anemometer (CTA) response are described. A method by which sine wave testing can be implemented on a commercial CTA by using mutual induction is introduced. A frequency response determined with the technique is used to demonstrate that the square wave test gives a misleading indication of anemometer bandwidth unless interpreted carefully. The use of the discrete fast Fourier transform to deconvolute the pulse response and square wave is demonstrated. The transfer functions for a CTA's response to the tests and to variations in heat transfer are determined analytically. The system bandwidth, optimal balance settings and substrate thermal product are derived by a combination of the electronic tests and the model.