Experimental results of a fully pulsed subsonic air jet issuing into the still surrounding air are reported in this paper. The intermittent flow containing a period of no flow between pulses due to the mechanically excitation was gauged by a single wire hot-wire anemometer operated in a constant temperature mode. A range of the Reynolds and Strouhal numbers of 1 × 104 < Re < 4 × 104 and 0.0064 < St < 0.0076 respectively was used to define the jets. Results of the traverse measurement agreed with earlier findings demonstrating strong effects of the excitation on the radial profiles of the mean axial velocity of the jet. Within the parameter ranges investigated, the pulsed jets were found to be significantly more spreading than steady jets. A less dispersive pulsed jet, however, appeared at a higher jet exit velocity. Strikingly, contradictory trends in the jet growth and entrainment at the higher and lower Reynolds number were seen as the lower Reynolds number does not produce a widening radial profile as a result of the increasing Strouhal number. From the axial measurements, the pulsed jets were characterized by the pulsed dominated- and high turbulence steady jet region in which their existences heavily relied on the magnitudes of the controlled parameters. A less fluctuating pulsed jet associated with the reduced magnitudes of aggregate turbulence intensity and relative turbulence energy however, appeared at an increased Strouhal number. Comparative studies with the existing results of non-circular orifice jets i.e cruciform, elliptic, and triangular jets are also reported to display the decay rates of centerline axial velocity and the spreading rates of the jets which benefit for the practical purposes.
- Fluids Engineering Division
Mixing Enhancement by Using Turbulent Jets
Pratomo, HPS. "Mixing Enhancement by Using Turbulent Jets." Proceedings of the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. Volume 1D, Symposia: Transport Phenomena in Mixing; Turbulent Flows; Urban Fluid Mechanics; Fluid Dynamic Behavior of Complex Particles; Analysis of Elementary Processes in Dispersed Multiphase Flows; Multiphase Flow With Heat/Mass Transfer in Process Technology; Fluid Mechanics of Aircraft and Rocket Emissions and Their Environmental Impacts; High Performance CFD Computation; Performance of Multiphase Flow Systems; Wind Energy; Uncertainty Quantification in Flow Measurements and Simulations. Chicago, Illinois, USA. August 3–7, 2014. V01DT27A018. ASME. https://doi.org/10.1115/FEDSM2014-22086
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