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Title: The effect of nozzle aspect ratio on the heat transfer characteristics of elliptic impinging jet

The local heat transfer characteristics were investigated for a turbulent air jet issuing, normal to a heated flat plate, from an elliptic nozzle with various aspect ratios. Experimental parameters used in this study are the nozzle aspect ratio (AR = a/b) of 1, 1.5, 2, 3, and 4 having the same equivalent diameter D{sub e} and the nozzle-to-plate distance (L/D{sub e}) of 2, 4, 6, and 10. The temperature distribution on the heated flat plate was measured using a thermochromic liquid crystal and an improved image processing system that produced an unbiased color determination on liquid crystal. With varying the nozzle-to-plate distance, the isothermal contour on the heated flat plate showed an axis-switching phenomenon in its elliptical cross-section shape. As the aspect ratio of the elliptic nozzle increases, the heat transfer rate for the elliptic impinging jet with short nozzle-to-plate distance becomes larger than that of a circular jet in the impingement region. at L/D{sub e} = 2, the Nusselt number of an elliptic impinging jet with AR = 4 was maximum 15% higher than that of a circular impinging jet. This was caused by the engulfing large entrainment rate and large scale coherent structure of the elliptic jet.
Authors:
;  [1]
  1. Pohang Univ. of Science and Technology (Korea, Republic of)
Publication Date:
OSTI Identifier:
455393
Report Number(s):
CONF-951135--
ISBN 0-7918-1752-0; TRN: IM9716%%242
Resource Type:
Book
Resource Relation:
Conference: 1995 International mechanical engineering congress and exhibition, San Francisco, CA (United States), 12-17 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Heat transfer in turbulent flows -- 1995. HTD-Volume 318; Anand, N.K. [ed.] [Texas A and M Univ., College Station, TX (United States)]; Amano, R.S. [ed.] [Univ. of Wisconsin, Milwaukee, WI (United States)]; Armaly, B.F. [ed.] [Univ. of Missouri, Rolla, MO (United States)]; PB: 174 p.
Publisher:
American Society of Mechanical Engineers, New York, NY (United States)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; HEAT TRANSFER; JETS; TURBULENT FLOW; AIR FLOW; NOZZLES; EXPERIMENTAL DATA; DISTANCE