Influence of bypass ratio on subsonic and correctly expanded sonic co-flowing jets with finite lip thickness

Thanigaiarasu, S.; Shankar, M. Ravi; Rathakrishnan, E.

doi:10.1177/0954410018782511

Cited by 19 publications

(14 citation statements)

References 22 publications

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“…The numerical study was done for the following LTs: 1.0 D p , 1.5 D p , 2.0 D p , 2.5 D p , 3.0 D p , 3.5 D p , 4.0 D p , 4.5 D p , 5.0 D p , 6.0 D p , 7.0 D p , 8.0 D p , 10.0 D p and 15.0 D p . The results for LT 1.0 D p and 1.5 D p obtained from the experimental study correlates well with CFD results (Naren Shankar et al, 2016;Naren Shankar, 2017;Naren Shankar et al, 2018;Thanigaiarasu et al, 2018). In all the cases of the present study, exit dimensions for the primary and secondary jet are maintained constant.…”

Section: Numerical Studysupporting

confidence: 86%

“…At the same time, eddies begin appearing between the gap separating the two jet streams. Wake dominance causes to form a recirculation zone that bends the secondary jet toward primary jet, enhancing mixing (Naren Shankar et al, 2016;Naren Shankar et al, 2018;Thanigaiarasu et al, 2018;Naren Shankar and Dilip Raja, 2019;Naren Shankar, 2019). It is Figure 9 Axial total pressure decay for single jet and CFJ with LT 0.2 D p , 0.5 D p and1.0 D p worth noting that there occurs no IWZ for this LT, which in other way inferred that this LT is not sufficient to produce an influential wake region.…”

Section: Resultsmentioning

confidence: 99%

“…They found that thick lip enhanced mixing and VR to 0.4. Naren Shankar et al (2016), Thanigaiarasu et al (2018) and Naren found that increasing the LT resulted in an increase in the mixing up to a limit. Naren Shankar and Bennett (2019) found that at constant bypass ratio (BR), when the LT increased, mixing also increased.…”

Section: Introductionmentioning

confidence: 98%

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Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Krishnan

Raja

et al. 2020

AEAT

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Purpose This study aims to analyze co-flowing jets (CFJs) with constant velocity ratio (VR) and varying primary nozzle lip thickness (LT) to find a critical LT in CFJs below which mixing enhances and beyond which mixing inhibits. Design/methodology/approach CFJs were characterized with a constant VR and varying LTs. A single free jet with a diameter equal to that of a primary nozzle of the CFJ was used for characteristic comparison. Numerical simulation is carried out and is validated with the experimental results. Findings The results show that within a critical limit, the mixing enhanced with an increase in LT. This was signified by a reduction in potential core length (PCL). Beyond this limit, mixing inhibited leading to the elongation of PCL. This limit was controlled by parameters such as LT and constant VR. A new region termed as influential wake zone is identified. Practical implications In this study, the VR is maintained constant and bypass ratio (BR) was varied from low value to very high values. Presently, subsonic commercial turbo fan operates under low to ultra-high BR. Hence the present study becomes vital to the current scenario. Originality/value To the best of the authors’ knowledge, this is the first effort to find the critical value of LT for a constant VR for compressible co-flow jets. The CFJs with constant VR and varying LT have not been studied in the past. The present study focuses on finding a critical LT below which mixing enhances and above which mixing inhibits.

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Section: Numerical Studysupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

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Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Krishnan

Raja

et al. 2020

AEAT

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“…The above research cited discusses only the total pressure characteristics of the jet in both axial and radial directions. However, Naren Shankar et al (2016), Shankar (2017), Naren Shankar et al (2018), Thanigaiarasu et al (2019), Shankar et al (2020), Naren Shankar et al (2021) and Shankar et al (2021) observed other characteristics of the CFJ such as static pressure variation, velocity variation and streamline behaviour. Before these works, it was assumed that for a subsonic jet, the static pressure will be constant throughout the jet field but in the above mentioned works static pressure varied by 11% above and below atmospheric pressure.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of critical lip thickness of subsonic co-flowing jet

Shankar

Ganesan

Raja

et al. 2021

AEAT

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Purpose The effect of increasing lip thickness (LT) and Mach number on subsonic co-flowing Jet (CFJ) decay at subsonic and correctly expanded sonic Mach numbers has been analysed experimentally and numerically in this study. This study aims to a critical LT below which mixing enhances and above which mixing inhibits. Design/methodology/approach LT is the distance, separating the primary nozzle and the secondary duct, present in the co-flowing nozzle. The CFJ with LT ranging from 2 mm to 150 mm at jet exit Mach numbers of 0.6, 0.8 and 1.0 were studied in detail. The CFJ with 2 mm LT is used for comparison. Centreline total pressure decay, centreline static pressure decay and near field flow behaviour were analysed. Findings The result shows that the mixing enhances until a critical limit and a further increase in the LT does not show any variation in the jet mixing. Beyond this critical limit, the secondary jet has a detrimental effect on the primary jet, which deteriorates the process of mixing. The CFJ within the critical limit experiences a significantly higher mixing. The effect of the increase in the Mach number has marginal variation in the total pressure and significant variation in static pressure along the jet axis. Practical implications In this study, the velocity ratio (VR) is maintained constant and the bypass ratio (BR) was varied from low value to very high values for subsonic and correctly expanded sonic. Presently, commercial aircraft engine operates under these Mach numbers and low to ultra-high BR. Hence, the present study becomes essential. Originality/value This is the first effort to find the critical value of LT for a constant VR for a Mach number range of 0.6 to 1.0, compressible CFJ. The CFJs with constant VR of unity and varying LT, in these Mach number range, have not been studied in the past.

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“…Grooved and chevron nozzles are used as certain techniques in jet flow control (Elangovan and Rathakrishnan 2004;Tide and Srinivasan 2010;Kumar et al 2011). Nozzles are also modified to issue co-flowing jets to control the flow in the subsonic regime (Lovaraju and Rathakrishnan 2011;Shankar et al 2016;Shankar et al 2018;Shankar and Bennett 2019;Thanigaiarasu et al 2019;Shankar and Raja 2020).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Jet Mixing Characteristics Using Slotted Rectangular Tabs

Krishnaraj

Vinayagamurthy

2021

J. Aerosp. Technol. Manag.

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This article discusses the jet mixing effectiveness of rectangular tab with slots to distort the jet, thereby creating vortices of differing sizes to enhance the mixing. This article numerically investigates the effectiveness of slanted slotted/perforated rectangular tabs with the slot connecting the adjacent faces of the tab to control Mach 0.4 jet. To intensify the jet mixing process, two similar tabs with equal blockage ratio of 7% are placed at diametrically opposite locations of the convergent nozzle exit. The jet flow development in the axial and radial directions of the jet are investigated in detail. To measure the effectiveness of the slotted tabs, the results are compared with the free jet and with the jet operated with solid rectangular tab. The percentage reduction in the core length obtained is 84.1 and 74% for the jet employed with the slotted tab and the solid tab, respectively, when compared with the free jet. The results exhibit that the slotted tab distorts the jet in the near field to a greater extent when compared with the solid rectangular tab.

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Influence of bypass ratio on subsonic and correctly expanded sonic co-flowing jets with finite lip thickness

Cited by 19 publications

References 22 publications

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Characteristics of a co-flowing jet with varying lip thickness and constant velocity ratio

Numerical investigation of critical lip thickness of subsonic co-flowing jet

Investigation of Jet Mixing Characteristics Using Slotted Rectangular Tabs

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