Liquid jet injection in supersonic crossflow: Self-induced jet oscillations and its effects

Medipati, C and Deivandren, S and Govardhan, RN (2023) Liquid jet injection in supersonic crossflow: Self-induced jet oscillations and its effects. In: International Journal of Multiphase Flow, 158 .

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Abstract

Liquid jet injection into supersonic crossflow is one of the conceptually simple ways of fuel atomization in Scramjet engines. In the present work, we experimentally investigate the flow and spray formed due to the injection of a liquid jet in supersonic crossflow with free stream Mach number of M∞ = 2.5. The main focus of the work is on the unsteady aspects of the flow and spray, which are found to be self-induced and occur naturally in the flow. High speed shadowgraphy shows large variations in the windward spray edge and penetration with time. Unsteady pressure measurements in the liquid injection line show that in the presence of a supersonic crossflow, there exist significant self-generated mass flow fluctuations that occur in the injection line. The frequency of these oscillations is seen to be close to a Strouhal number, St = fδ /U∞ ≈ 0.007, close to the typical low frequencies seen in Shock-Wave Boundary Layer Interaction studies (δ = boundary layer thickness). The variations in mass flow rate within the injection line leads to significant fluctuations of the spray penetration and shocks. In particular, the variations in spray penetration with time is observed to lead to significant variations in both the droplet numbers and size at a given location in the generated spray, which can have significant implications for applications where such configurations are used.

Item Type:	Journal Article
Publication:	International Journal of Multiphase Flow
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd.
Keywords:	Boundary layer flow; Liquids; Mass transfer; Ramjet engines; Shock waves; Strouhal number; Supersonic aerodynamics, Bow shocks; Cross flows; Drop sizing; Injection lines; Jet injection; Liquid-jet; Shock-wave/boundary layer interactions; Spray in crossflow; Supersonic crossflow, Boundary layers
Department/Centre:	Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering) Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	10 Nov 2022 05:28
Last Modified:	10 Nov 2022 05:28
URI:	https://eprints.iisc.ac.in/id/eprint/77805

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