Nozzle-Geometry Effects on Upwind-Surface Properties of Turbulent Liquid Jets in Gaseous Crossflow

2010 ◽  
Vol 26 (5) ◽  
pp. 936-946 ◽  
Author(s):  
A. R. Osta ◽  
K. A. Sallam
Keyword(s):  
Surface Properties ◽  
Nozzle Geometry ◽  
Liquid Jets ◽  
Geometry Effects

Comparative study on interfacial oscillations of rectangular and elliptical liquid jets

2020 ◽  
Vol 234 (7) ◽  
pp. 1272-1286 ◽  
Author(s):  
Amin Jaberi ◽  
Mehran Tadjfar
Keyword(s):  
Aspect Ratio ◽  
Weber Number ◽  
High Speed ◽  
Nozzle Geometry ◽  
Liquid Jets ◽  
High Speed Photography ◽  
Aspect Ratios ◽  
Water Jets ◽  
Switching Phenomenon ◽  
Axis Switching

The instability characteristics and flow structures of water jets injected from rectangular and elliptical nozzles with aspect ratios varying from 2 to 6 were experimentally studied and compared. Shadowgraph technique was employed for flow visualization, and structures on the liquid jet surface were captured using high speed photography. It was found that disturbances originating from the nozzle geometry initially perturbed the liquid column, and then, at high jet velocities, disturbances generated within the flow dominated the jet surface. It was also found that rectangular nozzles introduced more disturbances into the flow than the elliptical ones. The characteristic parameters of axis-switching phenomenon including wavelength, frequency, and amplitude were measured and compared. Axis-switching wavelength was found to increase linearly with Weber number. Also, the wavelengths of rectangular jets were longer than the elliptical jets. Further, the frequency of axis-switching was shown to be reduced with increase of both Weber number and aspect ratio. It was observed that the axis-switching amplitude increased monotonically, reached a peak, and then decreased gradually. It was also found that the axis-switching amplitude varied with Weber number. At lower values of Weber number, the rectangular nozzles had higher amplitude than the elliptical nozzles. However, at higher values of Weber number, this relation was reversed, and the elliptical nozzles had the higher axis-switching amplitudes. This reversal Weber number decreased with the orifice aspect ratio. The reversal Weber number for aspect ratio of 4 was about 289, and it had decreased to 144 for the aspect ratio of 6.

Capillary Instability of Liquid Jets Issuing From Elliptic Nozzles

2010 ◽  
Author(s):  
Ghobad Amini ◽  
Ali Dolatabadi
Keyword(s):  
Surface Tension ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Stokes Equations ◽  
Practical Importance ◽  
Nozzle Geometry ◽  
Navier Stokes ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Breakup Mechanism

Breakup of a liquid jet issuing from an orifice is one of the classical problems in fluid dynamics due to its theoretical and practical importance. The main application of the process is in spray and droplet formation, which is of interest in the combustion in liquid-fuelled engines, ink-jet printers, coating systems, medical equipment, and irrigation device. The complexity of the breakup mechanism is due to the large number of parameters involved such as the design of injection nozzle, and thermodynamic states of both liquid and gas. In addition, different combinations of surface tension, inertia, and aerodynamic forces acting on the jet, define main breakup regimes. Effects of nozzle geometry on the behavior of liquid jets have been overlooked in the literature. Elliptic jets have never been investigated theoretically since mostly circular jets or liquid sheets have been analyzed; while experiments have shown that by using elliptical nozzles, entrainment and air mixing of fuel in combustion will be increased. In this article, instability of an elliptic liquid jet under the effect of inertia, viscous, and surface tension forces has been studied using temporal linear analyses. The effects of the gravity and the surrounding gas have been neglected. 1-D Cosserat equation (directed curve) has been used which can be considered as simplified form of Navier-Stokes equations. Results are comparable with classical Rayleigh mode of circular jet when the aspect ratio (ratio of major to minor axis) is one. Growth rate of instability on an elliptic liquid jet under various conditions has been compared with those of a circular jet. Results show that in comparison with a circular jet, the elliptic jet is more unstable and by increasing the aspect ratio the instability grows faster. In addition, similar to the circular case, the effect of viscosity is diminishing the growth rate for the elliptic jet.

Surface Properties During Primary Breakup of Turbulent Liquid Jets in Still Air

AIAA Journal ◽  
2003 ◽  
Vol 41 (8) ◽  
pp. 1514-1524 ◽  
Author(s):  
K. A. Sallam ◽  
G. M. Faeth
Keyword(s):  
Surface Properties ◽  
Liquid Jets ◽  
Primary Breakup

scholarly journals Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis

2019 ◽  
Vol 21 (1) ◽  
pp. 73-88 ◽  
Author(s):  
Adrian Pandal ◽  
Jose M Garcia-Oliver ◽  
Jose M Pastor
Keyword(s):  
Turbulence Modeling ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Computational Effort ◽  
Diffuse Interface ◽  
Cfd Modeling ◽  
Nozzle Geometry ◽  
Nozzle Flow ◽  
X Ray ◽  
Geometry Effects

Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the [Formula: see text]–Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier–Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.

scholarly journals Nozzle Geometry Effects on Corner Boundary Layers in Supersonic Wind Tunnels

AIAA Journal ◽  
2019 ◽  
Vol 57 (8) ◽  
pp. 3620-3623 ◽  
Author(s):  
Kshitij Sabnis ◽  
Holger Babinsky
Keyword(s):  
Boundary Layers ◽  
Wind Tunnels ◽  
Nozzle Geometry ◽  
Geometry Effects

scholarly journals Nozzle geometry effects in liquid jet array impingement

2009 ◽  
Vol 29 (11-12) ◽  
pp. 2211-2221 ◽  
Author(s):  
Brian P. Whelan ◽  
Anthony J. Robinson
Keyword(s):  
Nozzle Geometry ◽  
Liquid Jet ◽  
Geometry Effects ◽  
Jet Array

Measurements of the Spray Angle of Atomizing Jets

1983 ◽  
Vol 105 (4) ◽  
pp. 406-413 ◽  
Author(s):  
K.-J. Wu ◽  
C.-C. Su ◽  
R. L. Steinberger ◽  
D. A. Santavicca ◽  
F. V. Bracco
Keyword(s):  
Room Temperature ◽  
Density Ratio ◽  
Spray Angle ◽  
Nozzle Geometry ◽  
Liquid Jets ◽  
Injection Velocity ◽  
Liquid Density ◽  
Breakup Process ◽  
Strong Function ◽  
Test Conditions

Liquid jets are considered issuing from single-hole, round nozzles into quiescent gases under conditions such that they break up into a well defined conical spray immediately at the nozzle exit plane. The initial angles of such sprays were measured at room temperature by a spark photography technique. Water, n-hexane, and n-tetradecane at pressures from 11.1 MPa to 107.6 MPa were injected into gaseous N2 at pressures from 0.1 MPa to 4.2 MPa through sixteen nozzles of different geometry. Under the test conditions, the spray angle is found to be a strong function of the nozzle geometry and the gas-liquid density ratio and a weak function of the injection velocity. The measured trends are then discussed in the light of possible mechanisms of the breakup process and shown to be compatible with the aerodynamic theory of surface breakup if modified to account for nozzle geometry effects.

MIXING AND NOZZLE GEOMETRY EFFECTS ON FLAME STRUCTURE AND STABILITY

2007 ◽  
Vol 179 (1-2) ◽  
pp. 249-263 ◽  
Author(s):  
FAWZY EL-MAHALLAWY ◽  
AHMED ABDELHAFEZ ◽  
MOHY S. MANSOUR*
Keyword(s):  
Flame Structure ◽  
Nozzle Geometry ◽  
Structure And Stability ◽  
Geometry Effects
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