Co-Flowing Jet Control Using Lip Thickness Variation

R. Naren Shankar; S. Thanigaiarasu; S. Elangovan; E. Rathakrishnan

doi:10.1515/tjj-2018-0024

Article

Co-Flowing Jet Control Using Lip Thickness Variation

R. Naren Shankar , S. Thanigaiarasu , S. Elangovan and E. Rathakrishnan

Published/Copyright: July 28, 2018

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From the journal International Journal of Turbo & Jet-Engines Volume 38 Issue 3

Abstract

The control of co-flowing jets by varying lip thickness has been studied experimentally. Lip thickness is defined as the thickness of primary nozzle wall separating primary jet and secondary jet at the co-flowing nozzle exit. Co-flowing jets from a primary nozzle of diameter 10 mm (1.0 D_p) and a secondary duct with lip thickness (LT) 0.2 D_p, 1.0 D_p and 1.5 D_p at Mach numbers 0.6, 0.8 and 1.0 have been studied. Jet centreline total pressure decay, static pressure variation and jet mixing behaviour were analysed. The results show that the mixing of the co-flowing jet with substantial values of lip thickness is superior to the co-flowing jets with comparatively lower values of lip thickness. Co-flowing jets with lip thickness 1.0 D_p and 1.5 D_p experience a significantly higher mixing than the lip thickness 0.2 D_p jet, for all Mach numbers analyzed in the present study. Moreover, in the case of correctly expanded jets, the local static pressure is assumed to be equal to atmospheric pressure. This assumption becomes invalid for co-flowing jets with substantial lip thickness. The centerline static pressure varies sinusoidally above and below atmospheric pressure by a maximum of 11 %, which is due to wake dominance.

Keywords: co-flowing jet; lip thickness; mixing; static pressure; correctly expanded jets

PACS: 2010; jets; thorough nozzles 47.60.Kz

Funding statement: The High Speed Jet Laboratory was constructed and operational under a project funded by Aeronautics Research and Development Board (AR & DB). The financial support provided by AR & DB is highly acknowledged.

Acknowledgements

The authors would like to thank post graduate student G.M Pradeep Kumar for his invaluable contribution to the experimental activity.

Nomenclature

D_p: primary nozzle exit diameter (mm)
FMZ: fully merged zone
IMZ: initial merging zone
IZ: intermediate zone
L: potential core length
LT: lip thickness
M: local Mach number
M_p: primary jet exit Mach number
P_o: stagnation chamber pressure (kPa)
P_t: Pitot pressure (kPa)
P_s: local static pressure (kPa)
P_atm: atmospheric pressure (kPa)
X/D: axial position
R/D: radial position

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Received: 2017-07-15

Accepted: 2017-08-13

Published Online: 2018-07-28

Published in Print: 2021-08-26

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Articles in the same Issue

https://doi.org/10.1515/tjj-2018-0024

Keywords for this article

co-flowing jet; lip thickness; mixing; static pressure; correctly expanded jets