Measurements of axial instability waves in the near exit region of a high speed liquid jet

2011 ◽  
Vol 23 (12) ◽  
pp. 124105 ◽  
Author(s):  
J. E. Portillo ◽  
S. H. Collicott ◽  
G. A. Blaisdell
Keyword(s):  
High Speed ◽  
Liquid Jet ◽  
Instability Waves ◽  
Exit Region

NONLINEAR SIMULATION OF A HIGH-SPEED, VISCOUS LIQUID JET

1998 ◽  
Vol 8 (2) ◽  
pp. 155-178 ◽  
Author(s):  
J. H. Hilbing ◽  
Stephen D. Heister
Keyword(s):  
Viscous Liquid ◽  
High Speed ◽  
Liquid Jet ◽  
Nonlinear Simulation

Elastic liquid jet impaction on a high-speed moving surface

AIChE Journal ◽  
2012 ◽  
Vol 58 (11) ◽  
pp. 3568-3577 ◽  
Author(s):  
B. Keshavarz ◽  
S. I. Green ◽  
D. T. Eadie
Keyword(s):  
High Speed ◽  
Liquid Jet ◽  
Moving Surface ◽  
Elastic Liquid

Analysis of Micro-Explosion Phenomenon in a Constant Volume Chamber by Butanol-Biodiesel-Diesel Blend Fuel

2012 ◽  
Vol 443-444 ◽  
pp. 996-1006 ◽  
Author(s):  
Yu Liu ◽  
Jun Li ◽  
Ying Gao ◽  
Xin Mei Yuan
Keyword(s):  
Ambient Temperature ◽  
High Speed ◽  
Fuel Injection ◽  
Combustion Process ◽  
Constant Volume ◽  
Liquid Jet ◽  
Penetration Length ◽  
Temperature Conditions ◽  
Constant Volume Chamber ◽  
Jet Penetration

Different blend ratio of ternary component fuel was tested inside a constant volume chamber to investigate fuel injection and combustion under similar real engine working conditions. Because liquid spray light scattering is the different reflective rate from the liquid droplets and its surrounding background, butanol-biodiesel-diesel liquid jet penetration length can be highlighted in the images taken by high speed camera. Various ambient temperatures from 800K to 1200K and fuel composition were investigated. Measured results showed that sudden but repeatable drop of liquid jet penetration length at constant ambient temperature conditions of 800K and 900K. With ambient temperature increasing, this phenomenon became weak and disappeared. So more works focus on non-combusting experiments in order to delete combustion reflect. With butanol and biodiesel content increasing, micro explosion becomes prone excited and more violent because of the enlarged differences in volatilities and boiling point among the components. It is concluded that micro explosion which will distinctly enhances premixed combustion process and heat release rate but it present under certain initial ambient temperature conditions only and the light fuel content shouldn’t be lower than 10%.

scholarly journals Estimation of High-Speed Liquid-Jet Velocity Using a Pyro Jet Injector

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Naohisa Takagaki ◽  
Toru Kitaguchi ◽  
Masashi Iwayama ◽  
Atsushi Shinoda ◽  
Hiroshige Kumamaru ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Liquid Jet ◽  
Liquid Density ◽  
Liquid Viscosity ◽  
Ejection Velocity ◽  
Piston Motion ◽  
Ansys Fluent ◽  
Piston Displacement ◽  
Jet Velocity

AbstractThe high-speed liquid-jet velocity achieved using an injector strongly depends on the piston motion, physical property of the liquid, and container shape of the injector. Herein, we investigate the liquid ejection mechanism and a technique for estimating the ejection velocity of a high-speed liquid jet using a pyro jet injector (PJI). We apply a two-dimensional numerical simulation with an axisymmetric approximation using the commercial software ANSYS/FLUENT. To gather the input data applied during the numerical simulation, the piston motion is captured with a high-speed CMOS camera, and the velocity of the piston is measured using motion tracking software. To reproduce the piston motion during the numerical simulation, the boundary-fitted coordinates and a moving boundary method are employed. In addition, we propose a fluid dynamic model (FDM) for estimating the high-speed liquid-jet ejection velocity based on the piston velocity. Using the FDM, we consider the liquid density variation but neglect the effects of the liquid viscosity on the liquid ejection. Our results indicate that the liquid-jet ejection velocity estimated by the FDM corresponds to that predicted by ANSYS/FLUENT for several different ignition-powder weights. This clearly shows that a high-speed liquid-jet ejection velocity can be estimated using the presented FDM when considering the variation in liquid density but neglecting the liquid viscosity. In addition, some characteristics of the presented PJI are observed, namely, (1) a very rapid piston displacement within 0.1 ms after a powder explosion, (2) piston vibration only when a large amount of powder is used, and (3) a pulse jet flow with a temporal pulse width of 0.1 ms.

scholarly journals Atomization of a High Speed Liquid Jet by Wall Impingement

2005 ◽  
Vol 71 (703) ◽  
pp. 978-985
Author(s):  
Mikiya ARAKI ◽  
Chengjun XU ◽  
Seiichi SHIGA ◽  
Hideshi YAMADA ◽  
Shigeru HAYASHI ◽  
...  
Keyword(s):  
High Speed ◽  
Liquid Jet ◽  
Wall Impingement

scholarly journals Shear instability of an axisymmetric air–water coaxial jet

2018 ◽  
Vol 843 ◽  
pp. 575-600 ◽  
Author(s):  
Jean-Philippe Matas ◽  
Antoine Delon ◽  
Alain Cartellier
Keyword(s):  
Surface Tension ◽  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Convective Instability ◽  
Scaling Laws ◽  
Shear Instability ◽  
Liquid Jet ◽  
Absolute Instability ◽  
Instability Waves

We study the destabilization of a round liquid jet by a fast annular gas stream. We measure the frequency of the shear instability waves for several geometries and air/water velocities. We then carry out a linear stability analysis, and show that there are three competing mechanisms for the destabilization: a convective instability, an absolute instability driven by surface tension and an absolute instability driven by confinement. We compare the predictions of this analysis with experimental results, and propose scaling laws for wave frequency in each regime. We finally introduce criteria to predict the boundaries between these three regimes.

Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage

2020 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Air Flow ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Swirl Number ◽  
Flow Swirl ◽  
Air Stream ◽  
The Impact

Abstract This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42 and 0.73) using swirl vanes at air inlet having angles of 0°, 15°, 30° and 45° respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High speed (@ 500 fps) images of the spray were captured and those images were processed using MATLAB to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory and the jet spread in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet, but also result in spray with high jet spread and spray area. Based on the results, correlations for the spray path have been proposed which incorporates the effects of the swirl number of the air flow.

Comparison in High-Speed Droplet Impact Between Single and Multiple Collisions Against a Wall Covered With a Liquid Film

2019 ◽  
Author(s):  
Yoichiro Fukuchi ◽  
Tomoki Kondo ◽  
Keita Ando
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
High Speed ◽  
Water Layer ◽  
Liquid Jet ◽  
Surface Erosion ◽  
Single Droplet ◽  
Cleaning Efficiency ◽  
Droplet Impingement ◽  
Wall Shear

Abstract In semiconductor industry, liquid jet cleaning plays an important role because of its high cleaning efficiency and low environmental load. However, its cleaning mechanism is not revealed in detail because the experimental observation of high-speed and sub-micron droplets is challenging. Furthermore, higher impact velocity may give rise to surface erosion due to water-hammer shock loading from the impingement. To study cleaning mechanisms and surface erosion, numerical simulation of droplet impingement accounting for both viscosity and compressibility is an effective approach. In the previous study, wall-shear-flow generation has evaluated from the simulation of high-speed single droplet impingement. To evaluate more practical model of jet cleaning application, simulation of two droplets simplifying mono-dispersed splay of droplet train is favorable. Here, we numerically simulated impingement of two droplets, which allows for evaluating water-hammer pressure and wall shear stress. We consider the case of two water droplets (200 μm in diameter) that collides continuously, at speed 50 m/s, at the inter-droplet distance from 250 to 400 μm, with a no-slip rigid wall covered with a water layer (100 μm in thickness). The simulation is based on compressible Navier-Stokes equations for axisymmetric flow and the mixture of two components appears in numerically diffusion interface expressed by the volume average and advection equation. The simulation is solved by finite-volume WENO scheme that can capture both shock waves and material interface. In our simulation, the impingement of second droplet impingement gain higher shear stress than the single droplet impingement. At the case that the inter-droplet distance is 300 μm, maximum shear stress is 30.22 kPa (at the second droplet impingement), which is much larger than at the first droplet impingement (8.42 kPa). This result indicates how the second droplet impingement make wall shear flow induced by first droplet impingement stronger. From the parameter study of the inter-droplet distance, we can say that wall shear stress gets stronger as water layer thickness decreases. Furthermore, the maximum wall pressure is 1.96 MPa at the second droplet impingement, which is larger than at the first droplet impingement (1.46 MPa). From this study, the evaluation of surface erosion caused by jet cleaning is expected. The simulation suggests that multiple droplets impingement continuously may gain higher cleaning efficiency, which will give us a fundamental insight into liquid jet cleaning technologies. For further study, simulation of water column impingement and comparing the result of impingement of two droplets are expected.

Experimental Characterization of Intrinsic Properties Associated With Air-Assisted Liquid Jet and Liquid Sheet

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
K. Balaji ◽  
V. Sivadas ◽  
Vishnu Radhakrishna ◽  
Khushal Ashok Bhatija ◽  
K. Sai Charan
Keyword(s):  
High Speed ◽  
Liquid Sheet ◽  
Interfacial Instability ◽  
Wave Number ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Experimental Characterization ◽  
Interfacial Wave ◽  
Visualization Techniques

The present study focuses on experimental characterization of interfacial instability pertinent to liquid jet and liquid sheet in the first wind-induced zone. To accomplish this objective, the interfacial wave growth rate, critical wave number, and breakup frequency associated with air-assisted atomizer systems were extracted by utilizing high-speed flow visualization techniques. For a range of liquid to gas velocities tested, nondimensionalization with appropriate variables generates the corresponding correlation functions. These functions enable to make an effective comparison between interfacial wave developments for liquid jet and sheet configurations. It exhibits liquid sheets superiority over liquid jets in the breakup processes leading to efficient atomization.

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