Effect of swirl on mixing in underexpanded supersonic airflow

A. Abdelhafez; A. K. Gupta

doi:10.2514/1.48335

Effect of swirl on mixing in underexpanded supersonic airflow

A. Abdelhafez^*
, A. K. Gupta

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

6 Scopus citations

Abstract

This study examines the effect of imparting swirl to underexpanded nozzle airflow on supersonic mixing under matched mass flow conditions. A convergent nozzle with swirling capabilities is used to generate the underexpanded airflow. Fuel is injected coaxially at the nozzle throat. Nonreacting conditions are considered, wherein fuel is simulated by mixtures of helium, argon, and krypton inert gases. It was found that the positive effect of swirl on supersonic mixing is noticeable, even at the low degree of swirl examined here. Better mixing was observed between the supersonic and subsonic parts of the diamond-shock air flowfield at no fuel injection as well as between the supersonic air and the subsonic injected fuel. The compressible mixing-layer thickness was found to increase slightly with swirl. However, when normalized to its incompressible counterpart, the compressible thickness was observed to decrease with swirl, because the former increases more with swirl than the latter. Decreasing the air-fuel relative Mach number and/or density ratio was found to deteriorate mixing. On the other hand, decreasing the compressibility of the injected fuel (i.e., injecting fuel at lower subsonic Mach numbers) improves mixing.

Original language	English
Pages (from-to)	117-131
Number of pages	15
Journal	Journal of Propulsion and Power
Volume	27
Issue number	1
DOIs	https://doi.org/10.2514/1.48335
State	Published - 2011
Externally published	Yes

Bibliographical note

Funding Information:
This work was supported by the Space Vehicle Technology Institute, jointly funded by NASA, the Department of Defense, and the U.S. Air Force, within the NASA Constellation University Institutes Project, with Claudia Meyer as the Project Manager. This support is gratefully acknowledged. The simulation packages CFD-GEOM, CFD-FASTRAN, and CFD-VIEW were provided by ESI Group and CFD Research Corporation. This support is gratefully acknowledged. Help and support provided by Kenneth H. Yu, University of Maryland, with the design of the Mie-scattering setup, is greatly appreciated. The assistance provided by Adam Kareem in data acquisition is also appreciated.

ASJC Scopus subject areas

Aerospace Engineering
Fuel Technology
Mechanical Engineering
Space and Planetary Science

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Cite this

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title = "Effect of swirl on mixing in underexpanded supersonic airflow",

abstract = "This study examines the effect of imparting swirl to underexpanded nozzle airflow on supersonic mixing under matched mass flow conditions. A convergent nozzle with swirling capabilities is used to generate the underexpanded airflow. Fuel is injected coaxially at the nozzle throat. Nonreacting conditions are considered, wherein fuel is simulated by mixtures of helium, argon, and krypton inert gases. It was found that the positive effect of swirl on supersonic mixing is noticeable, even at the low degree of swirl examined here. Better mixing was observed between the supersonic and subsonic parts of the diamond-shock air flowfield at no fuel injection as well as between the supersonic air and the subsonic injected fuel. The compressible mixing-layer thickness was found to increase slightly with swirl. However, when normalized to its incompressible counterpart, the compressible thickness was observed to decrease with swirl, because the former increases more with swirl than the latter. Decreasing the air-fuel relative Mach number and/or density ratio was found to deteriorate mixing. On the other hand, decreasing the compressibility of the injected fuel (i.e., injecting fuel at lower subsonic Mach numbers) improves mixing.",

author = "A. Abdelhafez and Gupta, \{A. K.\}",

note = "Funding Information: This work was supported by the Space Vehicle Technology Institute, jointly funded by NASA, the Department of Defense, and the U.S. Air Force, within the NASA Constellation University Institutes Project, with Claudia Meyer as the Project Manager. This support is gratefully acknowledged. The simulation packages CFD-GEOM, CFD-FASTRAN, and CFD-VIEW were provided by ESI Group and CFD Research Corporation. This support is gratefully acknowledged. Help and support provided by Kenneth H. Yu, University of Maryland, with the design of the Mie-scattering setup, is greatly appreciated. The assistance provided by Adam Kareem in data acquisition is also appreciated.",

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N2 - This study examines the effect of imparting swirl to underexpanded nozzle airflow on supersonic mixing under matched mass flow conditions. A convergent nozzle with swirling capabilities is used to generate the underexpanded airflow. Fuel is injected coaxially at the nozzle throat. Nonreacting conditions are considered, wherein fuel is simulated by mixtures of helium, argon, and krypton inert gases. It was found that the positive effect of swirl on supersonic mixing is noticeable, even at the low degree of swirl examined here. Better mixing was observed between the supersonic and subsonic parts of the diamond-shock air flowfield at no fuel injection as well as between the supersonic air and the subsonic injected fuel. The compressible mixing-layer thickness was found to increase slightly with swirl. However, when normalized to its incompressible counterpart, the compressible thickness was observed to decrease with swirl, because the former increases more with swirl than the latter. Decreasing the air-fuel relative Mach number and/or density ratio was found to deteriorate mixing. On the other hand, decreasing the compressibility of the injected fuel (i.e., injecting fuel at lower subsonic Mach numbers) improves mixing.

AB - This study examines the effect of imparting swirl to underexpanded nozzle airflow on supersonic mixing under matched mass flow conditions. A convergent nozzle with swirling capabilities is used to generate the underexpanded airflow. Fuel is injected coaxially at the nozzle throat. Nonreacting conditions are considered, wherein fuel is simulated by mixtures of helium, argon, and krypton inert gases. It was found that the positive effect of swirl on supersonic mixing is noticeable, even at the low degree of swirl examined here. Better mixing was observed between the supersonic and subsonic parts of the diamond-shock air flowfield at no fuel injection as well as between the supersonic air and the subsonic injected fuel. The compressible mixing-layer thickness was found to increase slightly with swirl. However, when normalized to its incompressible counterpart, the compressible thickness was observed to decrease with swirl, because the former increases more with swirl than the latter. Decreasing the air-fuel relative Mach number and/or density ratio was found to deteriorate mixing. On the other hand, decreasing the compressibility of the injected fuel (i.e., injecting fuel at lower subsonic Mach numbers) improves mixing.

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Effect of swirl on mixing in underexpanded supersonic airflow

Abstract

Bibliographical note

ASJC Scopus subject areas

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