A novel gas channel experiment was constructed to study the development of
high Atwood number Rayleigh-Taylor mixing. Two gas streams, one containing air
and the other containing helium-air mixture, flow parallel to each other separated by
a thin splitter plate. The streams meet at the end of a splitter plate leading to the
formation of an unstable interface and of buoyancy driven mixing. This buoyancy
driven mixing experiment allows for long data collection times, short transients and
was statistically steady. The facility was designed to be capable of large Atwood
number studies of ABtB ~ 0.75. We describe work to measure the self similar evolution
of mixing at density differences corresponding to 0.035 < ABtB < 0.25. Diagnostics
include a constant temperature hot-wire anemometer, and high resolution digital
image analysis. The hot-wire probe gives velocity, density and velocity-density
statistics of the mixing layer. Two different multi-position single-wire techniques
were used to measure the velocity fluctuations in three mutually perpendicular
directions. Analysis of the measured data was used to explain the mixing as it
develops to a self-similar regime in this flow. These measurements are to our knowledge, the first use of hot-wire anemometry in the Rayleigh-Taylor community.
Since the measurement involved extensive calibration of the probes in a binary gas
mixture of air and helium, a new convective heat transfer correlation was formulated
to account for variable-density low Reynolds number flows past a heated cylinder. In
addition to the hot-wire measurements, a digital image analysis procedure was used
to characterize various properties of the flow and also to validate the hot-wire
measurements. A test of statistical convergence was performed and the study
revealed that the statistical convergence was a direct consequence of the number of
different large three-dimensional structures that were averaged over the duration of
the run.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4183 |
| Date | 30 October 2006 |
| Creators | Banerjee, Arindam |
| Contributors | Andrews, Malcolm J. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 6509822 bytes, electronic, application/pdf, born digital |
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