Hot-wire calibration at high subsonic and transonic mach numbers

Watmuff, J, Jones, M, Henbest, S and Blandford, A 2012, 'Hot-wire calibration at high subsonic and transonic mach numbers', in P.A. Brandner and B.W. Pearce (ed.) Proceedings of the 18th Australasian Fluid Mechanics Conference (AFMC 2012), Launceston, Australia, 3-7 December 2012, pp. 1-4.


Document type: Conference Paper
Collection: Conference Papers

Title Hot-wire calibration at high subsonic and transonic mach numbers
Author(s) Watmuff, J
Jones, M
Henbest, S
Blandford, A
Year 2012
Conference name 18th Australasian Fluid Mechanics Conference (AFMC 2012)
Conference location Launceston, Australia
Conference dates 3-7 December 2012
Proceedings title Proceedings of the 18th Australasian Fluid Mechanics Conference (AFMC 2012)
Editor(s) P.A. Brandner and B.W. Pearce
Publisher Australasian Fluid Mechanics Society (AFMS)
Place of publication Melbourne, Australia
Start page 1
End page 4
Total pages 4
Abstract A technique has been developed to change the Resistance Ratio (RR) of a constant-temperature hot-wire anemometer: while it is operating; under electronic control; and at relatively high frequencies. The technique has been implemented by modifying anemometers built at DSTO that follow the design of Watmuff [3]. The modifications include adding a device for electronic switching of additional bridge resistors in parallel with the balance resistor, Rb. Severe large-amplitude transients are observed as a result of the switching even for moderate changes in RR. However, these large-amplitude transients contain very high frequency components and they have a corresponding rapid decay rate and they appear to be benign in the sense that there has not been any noticeable increase in hotwire breakage. Observations demonstrate that the RR switching also introduces lower frequency components that appear to be identical to the usual electronic square wave response that is used to tune constant-temperature anemometers. A theoretical model for the transient behaviour using a similar generalized Laplace transform method to Watmuff [2] remains to be derived. Calibration data at high subsonic and transonic Mach numbers have been obtained in the DSTO TransonicWind Tunnel (TWT). The benefit of high-speed dynamic alternation of RR is that the calibration and application data points for multiple RR can be obtained using a single measurement realization. Furthermore, almost identical flow conditions are experienced at each RR compared to the conventional method where data are obtained as independent realizations at each RR.
Subjects Engineering Instrumentation
Keyword(s) Hot-wire calibration
Transonic
Copyright notice © 2012 Australasian Fluid Mechanics Society (AFMS)
ISBN 9780646583730
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