The study of Taylor-Couette flows with superimposed isothermal and heated axial flows at high Taylor numbers

Citation

Shih, Angela Chao-Hsuan (1994) The study of Taylor-Couette flows with superimposed isothermal and heated axial flows at high Taylor numbers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3r06-hm27. https://resolver.caltech.edu/CaltechETD:etd-12112007-104052

Abstract

This experimental study investigates the effect of an isothermal or heated superimposed axial flow on a Taylor-Couette flow in an open, vertical annulus with the inner cylinder rotating. The tangential component of the velocity is measured using a hot-wire anemometer, and the velocity power spectra are calculated. The flows studied are for Taylor numbers ranging from 1.2 x 10[superscript 7] to 2.4 x 10 [superscript 7], and the axial Reynolds number from 0 to 2500. At a low axial Reynolds number, the power spectrum of the velocity measurements shows a single dominant frequency. The frequency is indicative of the uniformly-spaced vortices passing through the anemometer, and roughly corresponds with the axial velocity divided by the vortex spacing. As the rotational speed is increased at a fixed axial flow rate, the dominant frequency decreases, indicating a change in the size of the vortices. As the axial Reynolds number is increased at a fixed rotational speed, the power spectra first indicate a decrease in the dominant frequency, and then a subsequent increase in the other frequencies. For very large axial flow rates, the power spectra indicate a broad distribution in frequencies.

The experiment also include the measurements of the transient and the local fluid temperatures, and the corresponding temperature spectra are calculated. Heating of the axial flow also changes the characteristic of the velocity spectra, where peaks at higher frequencies emerge in the spectra. In heated flows, the peaks of the greatest spectral strength in the velocity and temperature spectra are different, possibly indicating that the largest temperature and velocity fluctuations occur in different directions. The average temperature measurements indicate that as the axial flow rate is increased, the mean temperature distribution curves shift upward. The temperature ratio, (T[subscript max] - T[subscript min])/(T[subscript in] - T[subscript out]), also increases with an increasing in the axial Reynolds numbers.

Thesis Files