Study of Interaction between Unsteady Supersonic Jet and Vortex Rings Discharged from Elliptical Cell

2018 ◽  
Vol 910 ◽  
pp. 137-142
Author(s):  
Kazumasa Kitazono ◽  
Hiroshi Fukuoka ◽  
Nao Kuniyoshi ◽  
Minoru Yaga ◽  
Eri Ueno ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Vortex Ring ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Navier Stokes ◽  
Vortex Rings ◽  
Thermodynamic Conditions

Pulsed laser ablation with an elliptical cell gives well-defined thermodynamic conditions to the growth of high-quality thin films. The unsteady supersonic jet formed by the shock tube with small high-pressure chamber was used as a simple alternative model of pulsed laser ablation. The vortex ring formed by the shock wave is important to reveal behavior of unsteady supersonic jet discharged from elliptical cell. However, there has been little effort to investigate the interaction between the vortex ring and the jet. The purpose of the present study is to investigate the behavior of the vortex rings and the jet. The experiment and numerical calculation were carried out by schlieren method and by solving the axisymmetric two-dimensional compressible Navier-Stokes equations, respectively. The system of the calculation and the experiment is a model of laser ablation of a certain duration followed by a discharging process through the exit. Moreover, a parametric study was performed to demonstrate the effect of pressure ratio on the interaction among vortex rings and the supersonic jet. The interaction between the supersonic jet and the vortex rings increased the velocity of the supersonic jet up to the magnitude of the velocity at the center of the vortex rings. Closing a distance between the vortex ring and the jet is higher interaction between the vortex rings.

Dynamics of a vortex ring in a rotating fluid

1996 ◽  
Vol 317 ◽  
pp. 215-239 ◽  
Author(s):  
R. Verzicco ◽  
P. Orlandi ◽  
A. H. M. Eisenga ◽  
G. J. F. Van Heijst ◽  
G. F. Carnevale
Keyword(s):  
Vortex Ring ◽  
Stokes Equations ◽  
Rotation Axis ◽  
Three Dimensional ◽  
Swirl Flow ◽  
Degree Of Polarization ◽  
Navier Stokes ◽  
Vortex Rings ◽  
Rotating Fluid ◽  
Translation Velocity

The formation and the evolution of axisymmetric vortex rings in a uniformly rotating fluid, with the rotation axis orthogonal to the ring vorticity, have been investigated by numerical and laboratory experiments. The flow dynamics turned out to be strongly affected by the presence of the rotation. In particular, as the background rotation increases, the translation velocity of the ring decreases, a structure with opposite circulation forms ahead of the ring and an intense axial vortex is generated on the axis of symmetry in the tail of the ring. The occurrence of these structures has been explained by the presence of a self-induced swirl flow and by inspection of the extra terms in the Navier–Stokes equations due to rotation. Although in the present case the swirl was generated by the vortex ring itself, these results are in agreement with those of Virk et al. (1994) for polarized vortex rings, in which the swirl flow was initially assigned as a ‘degree of polarization’.If the rotation rate is further increased beyond a certain value, the flow starts to be dominated by Coriolis forces. In this flow regime, the impulse imparted to the fluid no longer generates a vortex ring, but rather it excites inertial waves allowing the flow to radiate energy. Evidence of this phenomenon is shown.Finally, some three-dimensional numerical results are discussed in order to justify some asymmetries observed in flow visualizations.

Investigation of Vortex Structures for Supersonic Jet Interaction Flowfield

2015 ◽  
Vol 798 ◽  
pp. 546-550 ◽  
Author(s):  
Asel Beketaeva ◽  
Amr H. Abdalla ◽  
Yekaterina Moisseyeva
Keyword(s):  
Stokes Equations ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Bow Shock ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Trailing Vortices ◽  
Barrel Shock

The three-dimensional supersonic turbulent flow in presence of symmetric transverse injection of round jet is simulated numerically. The simulation is based on the Favre-averaged Navier-Stokes equations coupled with Wilcox’s turbulence model. The numerical solution is performed using ENO scheme and is validated with the experimental data that include the pressure distribution on the wall in front of the jet in the plane symmetry. The numerical simulation is used to investigate in detail the flow physics for a range of the pressure ratio . The well-known primary shock formations are observed (a barrel shock, a bow shock, and the system of λ-shock waves), and the vortices are identified (horseshoe vortex, an upper vortex, two trailing vortices formed in the separation region and aft of the bow shock wave, two trailing vortices that merge together into one single rotational motion). During the experiment the presence of the new vortices near the wall behind the jet for the pressure ratio is revealed.

Sound generation by coaxial collision of two vortex rings

2000 ◽  
Vol 424 ◽  
pp. 327-365 ◽  
Author(s):  
O. INOUE ◽  
Y. HATTORI ◽  
T. SASAKI
Keyword(s):  
Vortex Ring ◽  
Sound Pressure ◽  
Stokes Equations ◽  
Near Field ◽  
Time Integration ◽  
Relative Strength ◽  
Navier Stokes ◽  
Vortex Rings ◽  
Sound Waves ◽  
Change Of Direction

Sound pressure fields generated by coaxial collisions of two vortex rings with equal/unequal strengths are simulated numerically. The axisymmetric, unsteady, compressible Navier–Stokes equations are solved by a finite difference method, not only for a near field but also for a far field. The sixth-order-accurate compact Padé scheme is used for spatial derivatives, together with the fourth-order-accurate Runge–Kutta scheme for time integration. The results show that the generation of sound is closely related to the change of direction of the vortex ring motion induced by the mutual interaction of the two vortex rings. For the case of equal strength (head-on collision), the change of direction is associated with stretching of the vortex rings. Generated sound waves consist of compression parts and rarefaction parts, and have a quadrupolar nature. For the case of unequal strengths, the two vortex rings pass through each other; the weaker vortex ring moves outside the stronger vortex ring which shows a loop motion. The number of generated waves depends on the relative strength of the two vortex rings. The sound pressure includes dipolar and octupolar components, in addition to monopolar and quadrupolar components which are observed for the case of a head-on collision.

Study of Unsteady Supersonic Jet Using Shock Tube with Small High-Pressure Chamber with Elliptical Cell

2013 ◽  
Vol 767 ◽  
pp. 80-85 ◽  
Author(s):  
Motoki Sakamoto ◽  
Masazumi Matsui ◽  
Hiroshi Fukuoka ◽  
Minoru Yaga ◽  
Toshio Takiya
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Laser Ablation ◽  
Shock Tube ◽  
Static Pressure ◽  
Focal Point ◽  
Supersonic Jet ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
High Pressure Chamber

The unsteady supersonic jet formed by the shock tube with small high-pressure chamber was used as a simple alternative model of Pulsed laser ablation. Since the pressure of the shock wave formed by Pulsed laser ablation is very high, the interaction between the shock wave and the plume is important for the formation of nanoparticles especially under high background gas pressure. An elliptical cell is used for controlling the shock wave. The shock wave discharged in one focal point converge another focal point. Numerical calculation was carried out by solving the axisymmetric two-dimensional compressible Navier-Stokes equations. The wall static pressure monitored at the center of substrate is used to evaluate the influence of the shape and the pressure ratio on the behavior of the shock wave, the plume, and their interaction. As a result, it was found that the vortex ring was generated downstream of the cell, which is followed by the discharging shock wave from the cell exit. It was also found that the influence of the vortex ring on the wall static pressure at the center of the substrate.

Small High-Pressure Chamber Shock Tube

2012 ◽  
Author(s):  
Hiroshi Fukuoka ◽  
Minoru Yaga ◽  
Toshio Takiya
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Tube ◽  
Flat Plate ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Simple Alternative

The unsteady supersonic jet formed by the shock tube with small high-pressure section was used as a simple alternative system of pulsed laser ablation. The dynamic of the supersonic jet impinging upon a flat plate are discussed by comparing experimental and calculated results. The experiment and numerical calculation were carried out by schlieren method and by solving the axisymmetric two-dimensional compressible Navier-Stokes equations, respectively. The main parameters are distance between the open end of the shock tube and the flat plate, L/D, and the pressure ratio of the shock tube, Ph/Pb. Where, L, D, Ph and Pb are the distance between the open end of the shock tube and the flat plate, the diameter of the shock tube, pressure of the high and low section of the shock tube, respectively. Collision between the shock wave reflected at the flat plate and the head of supersonic jet takes place. Computational results well predict the experimental dynamic behavior of the shock wave and the supersonic jet. Marked increase in the static pressure on the flat plate under high Ph/Pb and short L/D is observed due to interaction between the shock wave and the unsteady jet flow.

Observations on the growth of YBa2Cu3O7-δ thin films on MgO by pulsed-laser ablation

1991 ◽  
Vol 49 ◽  
pp. 1068-1069
Author(s):  
M. Grant Norton ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Laser Ablation ◽  
Substrate Surface ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Laser Ablation Process ◽  
Deposition Parameters

Pulsed-laser ablation has been widely used to produce high-quality thin films of YBa2Cu3O7-δ on a range of substrate materials. The nonequilibrium nature of the process allows congruent deposition of oxides with complex stoichiometrics. In the high power density regime produced by the UV excimer lasers the ablated species includes a mixture of neutral atoms, molecules and ions. All these species play an important role in thin-film deposition. However, changes in the deposition parameters have been shown to affect the microstructure of thin YBa2Cu3O7-δ films. The formation of metastable configurations is possible because at the low substrate temperatures used, only shortrange rearrangement on the substrate surface can occur. The parameters associated directly with the laser ablation process, those determining the nature of the process, e g. thermal or nonthermal volatilization, have been classified as ‘primary parameters'. Other parameters may also affect the microstructure of the thin film. In this paper, the effects of these ‘secondary parameters' on the microstructure of YBa2Cu3O7-δ films will be discussed. Examples of 'secondary parameters' include the substrate temperature and the oxygen partial pressure during deposition.

scholarly journals Doping nanoparticles using pulsed laser ablation in a liquid containing the doping agent

2019 ◽  
Vol 1 (10) ◽  
pp. 3963-3972 ◽  
Author(s):  
Arsène Chemin ◽  
Julien Lam ◽  
Gaétan Laurens ◽  
Florian Trichard ◽  
Vincent Motto-Ros ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Doping Agent ◽  
Laser Ablation In Liquids ◽  
Dope Nanoparticles

While doping is crucial for numerous technological applications, its control remains difficult especially when the material is reduced down to the nanometric scale. We suggest a new way to dope nanoparticles using laser ablation in liquids.

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