Abstract
Numerical studies have been performed to visualize vortical flow structures emerged from jet cross-flow interactions. A single square jet issuing perpendicularly into a cross-flow was simulated first, followed by two additional scenarios, that is, inclined square jet at angles of 30° and 60° and round and elliptic jets at an angle of 90°, respectively. The simulation considers a jet to cross-flow velocity ratio of 2.5 and a Reynolds number of 225, based on the free-stream flow quantities and the jet exit width in case of square jet or minor axis length in case of elliptic jet. For the single square jet, the vortical flow structures simulated are in good qualitative agreement with the findings by other researchers. Further analysis reveals that the jet penetrates deeper into the cross-flow field for the normal jet, and the decrease of the jet inclination angle weakens the cross-flow entrainment in the near-wake region. For both noncircular and circular jet hole shapes, the flow field in the vicinity of the jet exit has been dominated by large-scale dynamic flow structures and it was found that the elliptic jet hole geometry has maximum “lifted-off” effect among three hole configurations studied. This finding is also in good qualitative agreement with existing experimental observations.
Highlights
The problem of injecting fluid through pipe/duct geometry into a mainstream cross-flow domain presents in many industrial and engineering applications, for example, turbine blade film cooling, fuel injection in IC engine, thrust, and noise control of S/VTOL aircraft, fuel-air mixing in gas turbine combustors, and pollutant dispersion from chimney stacks
Yuen and Martinez-Botas [4] carried out a systematic experimental study at three jet inclination angles of 30◦, 60◦, and 90◦ and identified the maximum cooling effectiveness, which was reached at a velocity ratio of 0.33 and jet angle of 30◦
The present paper focuses on the investigation of the effect of different jet inclination angles and hole geometries on the dynamic evolution process of vortical structures associated with jet and cross-flow interactions using direct numerical simulation (DNS) approach
Summary
The problem of injecting fluid through pipe/duct geometry into a mainstream cross-flow domain presents in many industrial and engineering applications, for example, turbine blade film cooling, fuel injection in IC engine, thrust, and noise control of S/VTOL aircraft, fuel-air mixing in gas turbine combustors, and pollutant dispersion from chimney stacks. Due to these wide range applications, the jet in crossflow (JICF) configuration has been the subject for numerous experimental and theoretical studies. Due to a “lifted-off ” effect of counterrotating vortex pair (CRVP) in the near field of a hole exit, the “cooled” jet flow tends to be “separated or detached” from the blade surface and this will cause the significant reduction of the cooling effectiveness
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