PASSIVE SCALAR MEASUREMENTS IN ACTIVELY EXCITED FREE SHEAR FLOWS

by

Steven Joseph Marques Junior

Master's Thesis submitted to the Faculty of the Virginia Tech in partial fulfillment of the requirements for the degree of

Master of Science

in

Department of Mechanical Engineering

Approved

U. Vandsburger

December 2, 1996
Blacksburg, Virginia

Abstract

The objectives of this study were to implement a system to measure mixing in non-reacting flows and to study the mass transfer characteristics of two actively excited turbulent jets. This thesis describes the acquisition and analysis of phase-locked concentration field data using planar Mie scattering from smoke particles and planar laser-induced fluorescence of acetone. Both techniques were shown to be effective in providing information for the actively excited nozzles. However, the laser-induced fluorescence technique was superior for revealing detail in the flowfield structure. Spatial mode control techniques were applied to a triangular nozzle with vibrating actuators as the three sides and a swirl nozzle with pulsating tangential air jets. The effect of the different spatial modes on jet column development and the far fields of both nozzles is presented. Two- and three-dimensional iso-intensity contours, showing the relative intensity of light scattered by the nozzle fluid marker, were generated to show the flow structure. The areas inside the iso-intensity contours in the far field were also measured to determine relative effectiveness of nozzle fluid transport. Large scale structures were visible in the three-dimensional iso-intensity contours from both nozzles. In addition, the transport of seeded nozzle fluid was enhanced by the spatial mode excitation for both nozzles. Spatial mode excitation was also able to affect the shape of the far field contour. In particular, the first counterrotating helical mode, m=1, generated the greatest effect on nozzle fluid transport and the most pronounced elliptical contour shape in the far field.


List of attached files

File NameSize (Bytes)
APPEND.PDF41,014 Bytes
BIBLIO.PDF14,468 Bytes
CH1.PDF21,925 Bytes
CH2.PDF32,345 Bytes
CH3.PDF34,623 Bytes
CH4.PDF35,398 Bytes
CH5.PDF11,500 Bytes
ETD.PDF43,142 Bytes
FIG2_1.PDF6,827 Bytes
FIG2_2.PDF5,527 Bytes
FIG2_3.PDF6,773 Bytes
FIG2_4.PDF4,689 Bytes
FIG3_1.PDF4,718 Bytes
FIG3_2.PDF5,581 Bytes
FIG3_3.PDF142,016 Bytes
FIG3_4.PDF194,285 Bytes
FIG3_5.PDF105,789 Bytes
FIG3_6.PDF139,041 Bytes
FIG3_7.PDF6,488 Bytes
FIG3_8.PDF205,592 Bytes
FIG3_9.PDF205,666 Bytes
FIG4_1.PDF7,672 Bytes
FIG4_10.PDF6,291 Bytes
FIG4_11.PDF372,682 Bytes
FIG4_12.PDF6,273 Bytes
FIG4_2.PDF5,161 Bytes
FIG4_3.PDF360,138 Bytes
FIG4_4.PDF363,341 Bytes
FIG4_5.PDF359,997 Bytes
FIG4_6.PDF114,435 Bytes
FIG4_7.PDF115,550 Bytes
FIG4_8.PDF113,765 Bytes
FIG4_9.PDF364,299 Bytes
VITA.PDF5,250 Bytes


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