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国际流体力学研究期刊
ESCI SJR: 0.206 SNIP: 0.446 CiteScore™: 0.9

ISSN 打印: 2152-5102
ISSN 在线: 2152-5110

国际流体力学研究期刊

DOI: 10.1615/InterJFluidMechRes.2017018780
pages 297-319

INFLUENCE OF NOZZLE EXIT CONDITIONS ON THE NEAR-FIELD MEAN FLOW CHARACTERISTICS OF LOW-ASPECT-RATIO RECTANGULAR JETS

Julien Barber
Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB, Canada
Meghdad Saediamiri
Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB, Canada
Madjid Birouk
Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB, R3T 5V6 Canada

ABSTRACT

The present study reports a systematic investigation of the effect of aspect ratio and Reynolds number on the mixing characteristics of low-aspect-ratio rectangular jets issuing from orifice plate nozzles. The nozzle aspect ratio (AR) is varied from 2 to 7, while the Reynolds number (with a constant equivalent diameter) is varied from 1 × 104 to 5 × 104. Particle image velocimetry (PIV) is used to determine the jet centerline mean velocity decay, jet velocity half-width spread, and potential core length, which are used to characterize the mechanisms of jet spreading in the near (x/De < 4) and mid (4 < x/De < 10) fields. The results show a distinctive difference in the mixing characteristics in the very near field (x/De < 2) for the low-AR range (AR = 2−7) examined in the present study. Jet entrainment is found to decrease in the near field with increasing AR for AR < 5. For AR > 4, however, the trend is reversed, that is, jet entrainment increases with increasing AR. Additionally, the results show that, in the midfield, the magnitude of jet decay and spreading rates increases with increasing AR and remains relatively constant with varying Reynolds number. In conclusion, Reynolds number is found to have a lesser impact than the AR on the mixing characteristics of a rectangular jet, suggesting a stronger aspect ratio dependence for low-aspect-ratio rectangular jets.


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