Date of Award

Fall 1981

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

John M. Kulhmen

Committee Member

Robert L. Ash

Committee Member

M. Hanif Chaudhry

Committee Member

Osama Kandill

Committee Member

Earl A. Thornton

Call Number for Print

Special Collections; LD4331.E56 C527

Abstract

An experimental investigation of the three dimensional mean temperature distribution of a rectangular buoyant surface thermal plume has been conducted for a range of buoyancies, velocity ratios, Reynolds numbers, and for various turbulence generating screens in the crossflow. This study has been motivated by a concern about the applicability of laboratory model data for predicting prototype plume behavior.

A large scale model has been built to study a buoyant, rectangular surface thermal plume which enters at right angles to a constant temperature uniform crossflow of depth equal to that of the plume. A large water tank and flume with weir type overflow discharge, and circulating piping system has been built. A three degrees of freedom traverse spanning the flume has been built, which can position any sensor mounted on this measuring system to investigate plume behavior.

For temperature measurement, a thermocouple rake has been used along with a pair of calibrated digital thermocouple indicators. The three dimensional average plume mean temperature distributions have been obtained. Upon calculation of the local average non-dimensional temperature, O, isotherm contours were obtained by linear interpolation.

Dye studies have been used to show plume width growth and centerline trajectories, and this data has been compared with width and centerline data from the temperature data. A range of values of internal (densimetric) Froude number from 0.79 to 1 .31, crossflow-to-jet velocity ratio from 0.56 to 1 '3, and Reynolds number from Ilk,200 to 22,700, have been investigated. Also, various turbulence generating grids have 'been placed in the crossflow and jet channels to investigate the effects of ambient turbulence.

The three dimensional isotherm contour data reveals the presence of a vortex structure on the upstream side of the jet or plume. This vortex is formed due to crossflow fluid which must turn downward to flow beneath the plume.

The dye studies have shown that there is a small, but measureable, effect of the turbulence grids in the crossflow on the jet width and trajectory. However, turbulence grids in the jet channel do not affect jet development. Also, jet Reynolds number has a relatively large effect on the mean plume characteristics for values of Reynolds numbers between 2,500 and 25,000. Surface heat transfer effects on the model data in the near field have been found to be small.

Rights

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DOI

10.25777/yy3t-nh23

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