TY - JOUR
T1 - The transient start of supersonic jets
AU - Radulescu, Matei I.
AU - Law, Chung K.
N1 - Funding Information:
This work was sponsored by the BP-Ford Carbon Mitigation Initiative at Princeton University. MIR was also supported by a Postdoctoral Fellowship from the Natural Sciences and Engineering Research Council of Canada. We are grateful to Fred Dryer of Princeton University for providing us with his insightful manuscript prior to its publication. Useful discussions with John Lee of McGill University and Victor Golub of the Institute of High Temperatures of the Russian Academy of Sciences are also greatly acknowledged. We wish to thank Gary Sharpe and Sam Falle of the University of Leeds for technical support for using their µCobra code.
PY - 2007/5/10
Y1 - 2007/5/10
N2 - This study investigates the initial transient hydrodynamic evolution of highly under-expanded slit and round jets. A closed-form analytic similarity solution is derived for the temporal evolution of temperature, pressure and density at the jet head for vanishing diffusive fluxes, generalizing a previous model of Chekmarev using Chernyi's boundary-layer method for hypersonic flows. Two-dimensional numerical simulations were also performed to investigate the flow field during the initial stages over distances of ∼1000 orifice radii. The parameters used in the simulations correspond to the release of pressurized hydrogen gas into ambient air, with pressure ratios varying between approximately 100 and 1000. The simulations confirm the similarity laws derived theoretically and indicate that the head of the jet is laminar at early stages, while complex acoustic instabilities are established at the sides of the jet, involving shock interactions within the vortex rings, in good agreement with previous experimental findings. Very good agreement is found between the present model, the numerical simulations and previous experimental results obtained for both slit and round jets during the transient establishment of the jet. Criteria for Rayleigh-Taylor instability of the decelerating density gradients at the jet head are also derived, as well as the formulation of a model addressing the ignition of unsteady expanding diffusive layers formed during the sudden release of reactive gases.
AB - This study investigates the initial transient hydrodynamic evolution of highly under-expanded slit and round jets. A closed-form analytic similarity solution is derived for the temporal evolution of temperature, pressure and density at the jet head for vanishing diffusive fluxes, generalizing a previous model of Chekmarev using Chernyi's boundary-layer method for hypersonic flows. Two-dimensional numerical simulations were also performed to investigate the flow field during the initial stages over distances of ∼1000 orifice radii. The parameters used in the simulations correspond to the release of pressurized hydrogen gas into ambient air, with pressure ratios varying between approximately 100 and 1000. The simulations confirm the similarity laws derived theoretically and indicate that the head of the jet is laminar at early stages, while complex acoustic instabilities are established at the sides of the jet, involving shock interactions within the vortex rings, in good agreement with previous experimental findings. Very good agreement is found between the present model, the numerical simulations and previous experimental results obtained for both slit and round jets during the transient establishment of the jet. Criteria for Rayleigh-Taylor instability of the decelerating density gradients at the jet head are also derived, as well as the formulation of a model addressing the ignition of unsteady expanding diffusive layers formed during the sudden release of reactive gases.
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U2 - 10.1017/S0022112007004715
DO - 10.1017/S0022112007004715
M3 - Article
AN - SCOPUS:34548149963
SN - 0022-1120
VL - 578
SP - 331
EP - 369
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
ER -