Date of Award

Fall 2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Aerospace Engineering

Committee Director

Colin P. Britcher

Committee Member

Drew Landman

Committee Member

Robert L. Ash

Call Number for Print

Special Collections; LD4331.E535 T36 2008

Abstract

This endeavor was motivated by the need to accurately quantify wind tunnel turbulence, a component of flow quality. The use of spheres and cones to find a turbulence correction factor has been mentioned in the literature but these methods are indirect approaches. To measure the amplitude and spectra of the velocity fluctuations, the hot wire anemometer is the only reliable instrument. A fiber-film sensor, which is similar in operation but with more mechanical rigidity, may be preferred over a hot wire owing to its robustness. In this work, the frequency response characteristics of the hot fiber-film sensor are studied.

The sensor was tested in a grid generated turbulent flow, which was nearly homogenous and isotropic, over a large speed range (20-110 mis) and at five different overheat ratios (1.2, 1.3, 1.4, 1.6 and 1.7). Power spectra of the turbulence were plotted and compared with the power spectra obtained by a conventional hot wire anemometer at the same flow conditions and a overheat ratio of 1.7. This comparison yielded a set of relative response plots that were considered to be indicative of the frequency response of the hot film circuit. The hot wire response was assumed to be correct and was used to estimate the transfer function of the hot film. The transfer function of the hot film circuit was found to be changing with speed and overheat ratio and further investigation is required into this behavior. The usable bandwidth of the hot film is typically inferior to the hot wire.

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DOI

10.25777/t0s6-qd34

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