Effect of clustering on linear plug nozzle flow field for overexpanded internal jet

Chutkey, Kiran; Viji, M.; Verma, Shashi B.

doi:10.1007/s00193-017-0707-y

Cited by 8 publications

(8 citation statements)

References 20 publications

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“…Similar to NPR=3, the case with NPR=6 also exhibits a dominant peak at 3.85 kHz. Similar observations were also reported in the earlier research works on plug nozzles 18,19 , where they observed dominant frequency at 3.36 kHz for NPR≈11 and at 3.8 kHz at NPR≈9. These high frequencies are attributed to the overall unsteadiness on the plug surface, and it is reported that the entire flow was fluctuating at this single frequency.…”

Section: Power Spectrasupporting

confidence: 91%

“…Irrespective of the lateral confinement, a prominent peak of equivalent power is observed at 0.85 kHz for NPR=6. Earlier works on the plug nozzle also reported a similar peak at the same frequency and have associated it with the overexpansion shock 18,19 .…”

Section: Power Spectrasupporting

confidence: 52%

“…They also attempted to identify the source of unsteadiness in the exit flow and the parameters governing the base pressure unsteadiness through quantification of shock oscillation frequency. Chutkey et al 19 also reported unsteadiness associated with the flow field of the linear plug nozzle and the effect of clustering. However, a proper understanding of the flow dynamics occurring on the plug surface due to over-expansion shock-induced flow separation and its associated unsteadiness and the effects of adding side-wall to the plug nozzle on the flow field is not clear till date.…”

Section: Introductionmentioning

confidence: 96%

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On the fluidic behavior of an over-expanded planar plug nozzle under lateral confinement

Chaudhary¹,

Krishna²,

Nanda³

et al. 2020

Preprint

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The present work aims to study the fluidic behavior on lateral confinement by placing side-walls on the planar plug nozzle through experiments. The study involves two cases of nozzle pressure ratio (NPR=3, 6), which correspond to over-expanded nozzle operating conditions. Steady-state pressure measurements, together with schlieren and surface oil flow visualization, reveal the presence of over-expansion shock and subsequent interaction and modification of the flow field on the plug surface. The flow remains attached to the plug surface for NPR=3; whereas, for NPR=6, a separated flow field with a recirculation bubble is observed. Spectral analysis of the unsteady pressure signals illustrates a clear difference between the attached and the separated flow. Besides, other flow features with a distinct temporal mode associated with and without lateral confinement are observed. The absence of lateral confinement reduces the intensity of low-frequency unsteadiness; however, on the contrary, the interaction region is relatively reduced under lateral confinement.

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Section: Power Spectrasupporting

confidence: 91%

Section: Power Spectrasupporting

confidence: 52%

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

On the fluidic behavior of an over-expanded planar plug nozzle under lateral confinement

Chaudhary¹,

Krishna²,

Nanda³

et al. 2020

Preprint

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“…The experimental work of S. B. Verma and M. Viji [10] consists in testing a linear plug nozzle. The nozzle is fed with air stored in a tank at ambient temperature and pressure, but both values are not explicitly provided in the reference paper; in this work, they have been assumed of 1 bar, as done also in [11], and 300 K, respectively.…”

Section: Resultsmentioning

confidence: 99%

Validation of a numerical strategy to simulate the expansion around a plug nozzle

Gagliardi

2023

Materials Research Proceedings

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Abstract. Rocket engines currently use traditional bell-shaped nozzles that have a fixed area ratio and can only operate at maximum efficiency at a given altitude. Plug nozzles have been proposed as an alternative solution to achieve higher performance over a larger altitude range. Unlike bell nozzles, the flow is free to expand along the plug, as it is no longer surrounded by solid boundaries. Therefore, plug nozzles can adapt to different altitudes by expanding the flow to ambient pressure, resulting in continuous altitude adaptation. Due to the high surface area that needs to be cooled, one of the main challenges of plug nozzle design is thermal management. However, the introduction of aerospike geometry, which is essentially a truncated plug nozzle, has helped mitigate this issue. Simulating an aerospike engine is challenging due to the interaction between the plume and the external flow, which is necessary to accurately predict thrust. In this work, a numerical strategy for predicting the performance of an aerospike engine, during a static fire, was developed and validated.

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“…In the experiments of Verma and Viji (2011); Chutkey et al (2012Chutkey et al ( , 2017Chutkey et al ( , 2018, planar and cluster jets from plugnozzles are investigated by monitoring the unsteady pressure spectra on the wall for different conditions. The varying unsteady jet dynamics in the presence and absence of a base flow, side plates, and wall truncation are studied.…”

Section: Introductionmentioning

confidence: 99%

On the unsteady dynamics of partially shrouded compressible jets

et al. 2021

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We experimentally investigate a partially shrouded sonic jet exiting from a planar nozzle with a solid wall on one side at two different nozzle pressure ratio (ζ = 4 and 5). We experimentally show for the first time that the inherent jet unsteadiness from the shock-induced flow separation on the wall and the emitted noise in the far-field is strongly coupled. The partially shrouded jet's lateral free expansion is also identified to be complicated, three-dimensional, and the produced noise is directional. The emitted acoustic pulses from the flapping-jet, the radiated noise from the shock-induced separation on the wall, and the shock-shear layer interaction on the other side of the wall are responsible for the generated acoustic disturbances. The non-uniform aeroacoustic forcing on the top and bottom portion of the partially wall-bounded jet shear layer leads to a self-sustained jet oscillation and a discrete sound emission.

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Effect of clustering on linear plug nozzle flow field for overexpanded internal jet

Cited by 8 publications

References 20 publications

On the fluidic behavior of an over-expanded planar plug nozzle under lateral confinement

On the fluidic behavior of an over-expanded planar plug nozzle under lateral confinement

Validation of a numerical strategy to simulate the expansion around a plug nozzle

On the unsteady dynamics of partially shrouded compressible jets

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