scholarly journals Effect of ambient pressure oscillation on the primary breakup of cylindrical liquid jet spray

2020 ◽  
Vol 12 ◽  
pp. 175682772093555
Author(s):  
Zhen Zhang ◽  
Dong-hyuk Shin
Keyword(s):  
Surface Tension ◽  
Mass Flow Rate ◽  
Flow Rate ◽  
Liquid Surface ◽  
Ambient Pressure ◽  
Pressure Oscillation ◽  
Liquid Jet ◽  
Liquid Surface Tension ◽  
Primary Breakup ◽  
Ambient Gas

The present simulation study investigates the effects of ambient pressure oscillation on cylindrical liquid jet sprays, using the volume of fluid method. The research is motivated by combustion instability in combustion engines, where strong harmonic pressure oscillation can damage internal structures. Oscillating pressure modulates not only the fuel mass flow rate but also the ambient gas density and liquid surface tension, and in liquid sprays, the ambient fluid density and surface tension can have substantial effects on spray breakup. In order to investigate the multiple property changes with ambient pressure oscillation, therefore, a new solver in OpenFOAM is developed. In the solver, liquid mass flow rate, ambient gas density, and liquid surface tension change simultaneously as a result of pressure oscillation. Simulations were conducted at a Reynolds number of 2000 and Weber number over 2000, conditions that are conducive to primary breakup in laminar flows. The simulations show that oscillations in ambient pressure significantly strengthen the surface instability of the liquid ligament, which depends on the surface tension–pressure coefficient, the mean pressure, and the amplitude of oscillation.

scholarly journals Trickle/pulse flow regime transition in downflow packed tower involving foaming liquids

2012 ◽  
Vol 18 (3) ◽  
pp. 349-359
Author(s):  
Vijay Sodhi
Keyword(s):  
Surface Tension ◽  
Liquid Flow ◽  
Liquid Surface ◽  
Regime Transition ◽  
Pulse Flow ◽  
Packed Tower ◽  
Flow Rates ◽  
Transition Boundary ◽  
Liquid Surface Tension ◽  
Pulsing Flow

The most of past studies in foaming trickle bed reactors aimed at the improvement of efficiency and operational parameters leads to high economic advantages. Conventionally most of the industries rely on frequently used gas continuous flow (GCF) where operational output is satisfactory but not yields efficiently as in pulsing flow (PF) and foaming pulsing flow (FPF). Hydrodynamic characteristics like regime transitions are significantly influenced by foaming nature of liquid as well as gas and liquid flow rates. This study?s aim was to demonstrate experimentally the effects of liquid flow rate, gas flow rates and liquid surface tension on regime transition. These parameters were analyzed for the air-aqueous Sodium Lauryl Sulphate and air-water systems. More than 240 experiments were done to obtain the transition boundary for trickle flow (GCF) to foaming pulsing flow (PF/FPF) by use excessive foaming 15-60 ppm surfactant compositions. The trickle to pulse flow transition appeared at lower gas and liquid flow rates with decrease in liquid surface tension. All experimental data had been collected and drawn in the form of four different transitional plots which are compared and drawn by using flow coordinates proposed by different researchers. A prominent decrease in dynamic liquid saturation was observed especially during regime transitional change. The reactor two phase pressure evident a sharp rise to verify the regime transition shift from GCF to PF/FPF. Present study reveals, the regime transition boundary significantly influenced by any change in hydrodynamic as well as physiochemical properties including surface tension.

scholarly journals Principle and Characteristics of Microparts Self-alignment using Liquid Surface Tension.

2000 ◽  
Vol 66 (2) ◽  
pp. 282-286 ◽  
Author(s):  
Kaiji SATO ◽  
Tomonori SEKI ◽  
Seiichi HATA ◽  
Akira SHIMOKOHBE
Keyword(s):  
Surface Tension ◽  
Liquid Surface ◽  
Liquid Surface Tension

Numerical Analysis of the Primary Breakup Under High-Altitude Relight Conditions Applying the Embedded DNS Approach to a Generic Prefilming Airblast Atomizer

2013 ◽  
Author(s):  
Benjamin Sauer ◽  
Nikolaos Spyrou ◽  
Amsini Sadiki ◽  
Johannes Janicka
Keyword(s):  
Surface Tension ◽  
Boundary Conditions ◽  
High Altitude ◽  
Ambient Pressure ◽  
Planar Geometry ◽  
Slight Variation ◽  
Strong Impact ◽  
Wall Film ◽  
Primary Breakup ◽  
Liquid Wall

The primary breakup under high-altitude relight conditions is investigated in this study where ambient pressure is as low as 0.4 bar and air, fuel and engine parts are as cold as 265 K. The primary breakup is crucial for the fuel atomization. As of today, the phenomena dictating the primary breakup are not fully understood. Direct Numerical Simulations (DNS) of liquid breakup under realistic conditions and geometries are hardly possible. The embedded DNS (eDNS) approach represents a reliable numerical tool to fill this gap. The concept consists of three steps: a geometry simplification, the generation of realistic boundary conditions for the DNS and the DNS of the breakup region. The realistic annular airblast atomizer geometry is simplified to a Y-shaped channel representing a planar geometry. Inside this domain the eDNS is located. The eDNS domain requires the generation of boundary conditions. A Large Eddy Simulation (LES) of the entire Y-shaped channel and a Reynolds-Averaged Navier-Stokes Simulation (RANS) of the liquid wall film are performed prior to the DNS. All parameters are stored transiently on all virtual DNS planes. These variables are then mapped to the DNS. Thus, high-quality boundary conditions are generated. The Volume-of-Fluid (VOF) method is used to solve for the two-phase flow. The results provide a qualitative insight into the primary breakup under realistic high-altitude relight conditions. Instantaneous snapshots in time illustrate the behavior of the liquid wall film along the prefilmer lip and illustrate the breakup process. It is seen that a slight variation of the surface tension force has a strong impact on the appearance of the primary breakup. Case 1 with the surface tension corresponding to kerosene at 293 K indicates large flow structures that are separated from the liquid sheet. By lowering the surface tension related to kerosene at 363 K, the breakup is dominated by numerous small structures and droplets. This study proves the applicability of the eDNS concept for investigating breakup processes as the transient nature of the phase interface behavior can be captured. At this time, the authors only present a qualitative insight which can be explained by the lack of quantitative data. The approach offers the potential of simulating realistic annular highly-swirled airblast atomizer geometries under realistic conditions.

scholarly journals Measurements and correlations for gas liquid surface tension at high pressure and high temperature

AIChE Journal ◽  
2018 ◽  
Vol 64 (11) ◽  
pp. 4110-4117 ◽  
Author(s):  
C. Leonard ◽  
J-H. Ferrasse ◽  
O. Boutin ◽  
S. Lefevre ◽  
A. Viand
Keyword(s):  
Surface Tension ◽  
High Pressure ◽  
High Temperature ◽  
Liquid Surface ◽  
Liquid Surface Tension

Self-alignment of microparts using liquid surface tension—behavior of micropart and alignment characteristics

2003 ◽  
Vol 27 (1) ◽  
pp. 42-50 ◽  
Author(s):  
Kaiji Sato ◽  
Kentaro Ito ◽  
Seiichi Hata ◽  
Akira Shimokohbe
Keyword(s):  
Surface Tension ◽  
Liquid Surface ◽  
Liquid Surface Tension

scholarly journals Microscale Surface Tension and its Applications

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 526 ◽  
Author(s):  
Pierre Lambert ◽  
Massimo Mastrangeli
Keyword(s):  
Surface Tension ◽  
Applied Research ◽  
Liquid Surface ◽  
Scientific Investigations ◽  
Liquid Surface Tension

More than 200 years since the earliest scientific investigations by Young, Laplace and Plateau, liquid surface tension is still the object of thriving fundamental and applied research [...]

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