Numerical study on the jet formation of simple-geometry heavy gas inhomogeneities

2019 ◽  
Vol 31 (2) ◽  
pp. 026103 ◽  
Author(s):  
E. Fan ◽  
Ben Guan ◽  
Chih-Yung Wen ◽  
Hua Shen
Keyword(s):  
Numerical Study ◽  
Jet Formation ◽  
Simple Geometry ◽  
Heavy Gas

Critical microjets in collapsing cavities

1995 ◽  
Vol 290 ◽  
pp. 183-201 ◽  
Author(s):  
Michael S. Longuet-Higgins ◽  
Hasan Oguz
Keyword(s):  
Flow Field ◽  
Spherical Harmonic ◽  
Velocity Potential ◽  
Initial Conditions ◽  
Numerical Study ◽  
Critical Flow ◽  
Jet Formation ◽  
Initial Flow ◽  
The Family ◽  
Self Similar

Inward microjets are commonly observed in collapsing cavities, but here we show that jets with exceptionally high velocities and accelerations occur in certain critical flows dividing jet formation from bubble pinch-off. An example of the phenomenon occurs in the family of flows which evolve from a certain class of initial conditions: the initial flow field is that due to a moving point sink within the cavity.A numerical study of the critical flow shows that in the neighbourhood of microjet formation the flow is self-similar. The local accelerations, velocities and distances scale as tβ-2, tβ-1 and tβ respectively, where β = 0.575. The velocity potential is approximately a spherical harmonic of degree ¼.

Experimental and Numerical Study of Spray Ignition for In-Flight Re-Light

2002 ◽  
Author(s):  
K. Lavergne ◽  
V. Quintilla ◽  
R. Lecourt ◽  
G. Lavergne
Keyword(s):  
Combustion Chamber ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Phase Flow ◽  
Ambient Conditions ◽  
Two Phase ◽  
Fuel Droplets ◽  
Experimental Configuration ◽  
Spark Plug ◽  
Simple Geometry

The context of this study is the prediction of re-ignition for turbojet engines after in-flight extinction at high altitude. Experiments have been performed on a simple geometry of a combustion chamber to test ignition at ambient conditions for three positions of the spark plug. Then, the two-phase flow corresponding to the experimental configuration has been simulated with the eulerian-lagrangian code used at ONERA. In parallel, a time dependent 0-dimensional model has been developed to predict the ignition of a cluster composed of fuel droplets when it is submitted to the spark inside the combustion chamber. This model has been applied on the two-phase flow computation in three elementary volumes located close to different spark plug positions. Ignition has been tested numerically for these clusters of drops, whose characteristics are dependent of their location in the combustion chamber, as well as, of the two-phase flow configuration in the geometry. Comparisons between experimental and numerical results are presented in this paper.

Experimental and numerical study on heavy gas contaminant dispersion and ventilation design for industrial buildings

2020 ◽  
Vol 55 ◽  
pp. 102016 ◽  
Author(s):  
Ou Han ◽  
Ying Zhang ◽  
Angui Li ◽  
Jianwei Li ◽  
Yuwei Li ◽  
...  
Keyword(s):  
Numerical Study ◽  
Contaminant Dispersion ◽  
Industrial Buildings ◽  
Heavy Gas

Jet formation in shock-heavy gas bubble interaction

2013 ◽  
Vol 29 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Zhi-Gang Zhai ◽  
Ting Si ◽  
Li-Yong Zou ◽  
Xi-Sheng Luo
Keyword(s):  
Gas Bubble ◽  
Jet Formation ◽  
Bubble Interaction ◽  
Heavy Gas

scholarly journals Shock interaction with a heavy gas cylinder: Emergence of vortex bilayers and vortex-accelerated baroclinic circulation generation

2003 ◽  
Vol 21 (3) ◽  
pp. 443-448 ◽  
Author(s):  
SANDEEP GUPTA ◽  
SHUANG ZHANG ◽  
NORMAN J. ZABUSKY
Keyword(s):  
Numerical Study ◽  
Finite Thickness ◽  
Weak Shock ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Gas Cylinder ◽  
Baroclinic Circulation ◽  
Strong Gradient ◽  
Heavy Gas ◽  
Piecewise Parabolic

We present a numerical study to late times of a Richtmyer–Meshkov environment: a weak shock (M= 1.095) interacting with a heavy cylindrical bubble. The bubble interface is modeled as a diffuse interfacial transition layer (ITL) with finite thickness. Our simulation with the piecewise parabolic method (PPM) yields very good agreement in large- and intermediate-scale features with Jacobs' experiment (Jacobs, 1993). We note the primary circulation enhancement deposited baroclinically upon the incident shock wave, and significant secondary baroclinic circulation enhancement, first observed in Zabusky and Zhang (2002). We propose that this vortex-accelerated circulation deposition is universal. These baroclinic processes are mediated by a strong gradient intensification and stretching of the ITL and result in close-lying vortex bilayers (VBLs) and the emergence of vortex projectiles (VPs). These account for the elongated, kidney-shaped morphology of the rolled up bubble domain at late times.

A Criterion for the Formation of Micro Synthetic Jets

2004 ◽  
Author(s):  
V. Timchenko ◽  
J. Reizes ◽  
E. Leonardi ◽  
G. de Vahl Davis
Keyword(s):  
Numerical Study ◽  
Reynolds Numbers ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Frequency Range ◽  
Jet Formation ◽  
Synthetic Jet Actuator ◽  
Computational Data ◽  
Flow Device ◽  
New Criterion

A synthetic jet actuator is a zero net mass flow device, which under appropriate conditions generates a continuous jet always directed away from the orifice. Because of limited experimental and computational data on micro-sized jets, there is a need for a criterion to determine the onset of the sustained jet regime. A numerical study of axisymmetric micro synthetic jets for a frequency range from 250 to 50,000 Hz, orifice diameters range from 20 to 200 μm, and Reynolds numbers from 6.5 to 35 has been performed in order to identify a general jet formation criterion. The parametric study has allowed us to develop a new criterion for the onset of micro synthetic jets with Stokes numbers less than 7.

Sign in / Sign up

Export Citation Format

Share Document