TY - GEN
T1 - Swirl effects on mixing in free underexpanded supersonic-nozzle airflow
AU - Abdelhafez, A.
AU - Kareem, A.
AU - Gupta, A. K.
PY - 2009
Y1 - 2009
N2 - This study complements our previous experimental investigation of the effects of swirl, convective Mach number, and air-fuel density ratio on shock structure in non-swirling and swirling underexpanded airflows with coaxial fuel injection. The effects of the above parameters on mixing are investigated experimentally in this present work. A novel nanosecond condensate-seeded Mie-scattering diagnostic technique was used to highlight the variation of mixedness within the flowfield. It was found that swirl enhances mixing significantly and reduces the strength of shock structure, which agrees with the findings of previous research. Higher convective Mach numbers allow for near-complete mixing of fuel jet with the surrounding airflow, as the interactions of shock structure with air/fuel shear layer are sufficient to achieve complete mixing. This behavior disappears steadily as convective Mach number is reduced. The shear angle between fuel and air jets was found to depend on fuel compressibility and air-fuel density ratio. Incompressible fuel jets and/or high air-fuel density ratios result in negative shear angles, which transition to positive if the fuel jet becomes compressible or the density gradient across shear layer decreases. If this density gradient approaches unity, the Baroclinic vorticity loses strength, which results in deteriorated mixing.
AB - This study complements our previous experimental investigation of the effects of swirl, convective Mach number, and air-fuel density ratio on shock structure in non-swirling and swirling underexpanded airflows with coaxial fuel injection. The effects of the above parameters on mixing are investigated experimentally in this present work. A novel nanosecond condensate-seeded Mie-scattering diagnostic technique was used to highlight the variation of mixedness within the flowfield. It was found that swirl enhances mixing significantly and reduces the strength of shock structure, which agrees with the findings of previous research. Higher convective Mach numbers allow for near-complete mixing of fuel jet with the surrounding airflow, as the interactions of shock structure with air/fuel shear layer are sufficient to achieve complete mixing. This behavior disappears steadily as convective Mach number is reduced. The shear angle between fuel and air jets was found to depend on fuel compressibility and air-fuel density ratio. Incompressible fuel jets and/or high air-fuel density ratios result in negative shear angles, which transition to positive if the fuel jet becomes compressible or the density gradient across shear layer decreases. If this density gradient approaches unity, the Baroclinic vorticity loses strength, which results in deteriorated mixing.
UR - https://www.scopus.com/pages/publications/78549250393
U2 - 10.2514/6.2009-1419
DO - 10.2514/6.2009-1419
M3 - Conference contribution
AN - SCOPUS:78549250393
SN - 9781563479694
T3 - 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition
BT - 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition
PB - American Institute of Aeronautics and Astronautics Inc.
ER -