Influence of nozzle geometry on underexpanded axisymmetric free jet characteristics

Shock Waves ◽  
2012 ◽  
Vol 22 (5) ◽  
pp. 427-434 ◽  
Author(s):  
K. Hatanaka ◽  
T. Saito
Keyword(s):  
Nozzle Geometry ◽  
Free Jet ◽  
Jet Characteristics

scholarly journals Flow Pressure Behavior Downstream of Ski Jumps

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 168 ◽  
Author(s):  
Agostino Lauria ◽  
Giancarlo Alfonsi ◽  
Ali Tafarojnoruz
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Dynamic Pressure ◽  
Pressure Head ◽  
Navier Stokes ◽  
Maximum Pressure ◽  
Navier Stokes Equations ◽  
Free Jet ◽  
Jet Characteristics ◽  
The Impact

Ski jump spillways are frequently implemented to dissipate energy from high-speed flows. The general feature of this structure is to transform the spillway flow into a free jet up to a location where the impact of the jet creates a plunge pool, representing an area for potential erosion phenomena. In the present investigation, several tests with different ski jump bucket angles are executed numerically by means of the OpenFOAM® digital library, taking advantage of the Reynolds-averaged Navier–Stokes equations (RANS) approach. The results are compared to those obtained experimentally by other authors as related to the jet length and shape, obtaining physical insights into the jet characteristics. Particular attention is given to the maximum pressure head at the tailwater. Simple equations are proposed to predict the maximum dynamic pressure head acting on the tailwater, as dependent upon the Froude number, and the maximum pressure head on the bucket. Results of this study provide useful suggestions for the design of ski jump spillways in dam construction.

Effects of nozzle geometry on kinetics in free-jet expansions

1984 ◽  
Vol 88 (20) ◽  
pp. 4474-4478 ◽  
Author(s):  
Hylton R. Murphy ◽  
David R. Miller
Keyword(s):  
Nozzle Geometry ◽  
Free Jet

Nozzle Spraying Model of Combustion Thermal Spray

2013 ◽  
Vol 655-657 ◽  
pp. 211-217 ◽  
Author(s):  
Wen Liang Guo ◽  
Zheng Guo
Keyword(s):  
Turbulent Flows ◽  
High Speed ◽  
Numerical Solutions ◽  
Substrate Surface ◽  
Ccd Camera ◽  
Nozzle Geometry ◽  
Flame Spraying ◽  
Free Jet ◽  
Powder Particles ◽  
Mixing Length Theory

The flame used in combustion flame spraying is typical of a high-temperature free jet. The flow fields of free jets are multi-phase flows that couple the mass and heat transfer. The analytical and numerical solutions to turbulent flows are engineering approximations. This work uses Prandtle’s mixing-length theory to describe the flame spreading of free combustion spray jet and uses nozzle spray model to describe the distribution of the powder particles sprayed from powder nozzle to the substrate surface. The nozzle geometry and the parameters determine the distribution of the powder particles. The nozzle spray model has the same physical meaning with the jet spreading angle. Experimental measurements were carried by a high-speed CCD camera.

scholarly journals Needle-Free Jet Injectors’ Geometry Design and Drug Diffusion Process Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Yunfei Wang ◽  
Long Yue ◽  
Lechuan Hu ◽  
Jing Wang
Keyword(s):  
Diffusion Process ◽  
Process Analysis ◽  
Subcutaneous Tissue ◽  
Nozzle Geometry ◽  
Drug Diffusion ◽  
Free Jet ◽  
Cylindrical Nozzle ◽  
Geometry Design ◽  
Nozzle Geometries ◽  
Jet Injectors

In order to study the injection and diffusion process of the drug in the subcutaneous tissue of a needle-free jet injectors (NFJIs) in detail and understand the influence of different nozzle geometry on the diffusion process of the drug, in this paper, numerical simulations were performed to study the diffusion process of the drug in the subcutaneous tissue of NFJIs with cylindrical nozzle. On this basis, the differences of the drug diffusion process with different nozzle geometries were analyzed. The results show that the drug diffused in the shape of ellipsoid in the subcutaneous tissue. The penetration of the drug into the subcutaneous tissue is deeper under the condition of conical nozzle and conical cylindrical nozzle at the same time. However, it takes longer to spread to the interface between skin and subcutaneous tissue in reverse.

scholarly journals The effect of nozzle geometry on the flow characteristics of small water jets

2006 ◽  
Vol 220 (12) ◽  
pp. 1739-1753 ◽  
Author(s):  
E Ghassemieh ◽  
H K Versteeg ◽  
M Acar
Keyword(s):  
Internal Combustion Engines ◽  
Cone Angle ◽  
Circular Cross Section ◽  
Flow Characteristics ◽  
Nozzle Geometry ◽  
Viscous Effects ◽  
Small Water ◽  
Jet Impact ◽  
The Stability ◽  
Jet Characteristics

A wide variety of processes make use of plain orifice nozzles. Fuel injectors for internal combustion engines incorporate these nozzles to generate finely atomized sprays. Processes such as jet cutting, jet cleaning, and hydroentanglement, on the other hand, use similar nozzles, but require coherent jets. The spray or jet characteristics depend on the stability of the flow emerging from the orifice. This problem has been extensively researched for nozzles with diameters above 300 μm. Much less is known about the characteristics of jets produced by nozzles with smaller diameters, where viscous effects and small geometric variations due to manufacturing tolerances are likely to play an increasing role. Results are presented of a wide-ranging investigation of geometry effects on the flow parameters and jet characteristics of nozzles with diameters between 120 and 170 μm. Nozzles with circular cross-section and conical, cone-capillary and capillary axial designs were investigated. For conical and cone-capillary nozzles, the effect of cone angle and effects due to interactions between adjacent nozzles in the multi-hole cone-capillary nozzles were studied. For capillary nozzles, the effects of diameter variations and inlet edge roundness for capillary nozzles were considered. Furthermore, the effect of varying the aspect ratio (ratio of major and minor axes) of elliptical nozzles was studied. Flowrate and jet impact force measurements were carried out to determine the discharge coefficient Cd, velocity coefficient Cv, and contraction coefficient Cc of the nozzles for supply pressures between 3 and 12 MPa. Visualizations of the jet flow were carried out in the vicinity of the nozzle exit in order to identify near-nozzle flow regimes and to study jet coherence. The relationship between nozzle geometry, discharge characteristics, and jet coherence is examined.

scholarly journals Study of air jet characteristics in air-conditioned rooms

2020 ◽  
Vol 324 ◽  
pp. 03009
Author(s):  
Yulia R. Kareeva ◽  
Vladimir N. Posokhin ◽  
Rinat G. Safiullin ◽  
Ksenia A. Bliznyakova
Keyword(s):  
Cross Sections ◽  
Longitudinal Velocity ◽  
Dimensionless Temperature ◽  
Buoyant Force ◽  
Free Jet ◽  
Air Jets ◽  
Air Jet ◽  
Calculation Results ◽  
Fluent Software ◽  
Jet Characteristics

The research deals with supply air jets in air-conditioned rooms which have different lengths. The study was conducted according to the numerical method using the Fluent software package. Discharge conditions are equal in all cases. As a result, dependences of main kinematic and geometric jet’s characteristics (width and jet range, longitudinal velocity profiles, axial velocity, average velocity of the back flow, flow rates in the cross sections of the direct and back flows, distribution of static pressure along the length of the jet) on longitudinal constraint parameter are determined (length of room). The calculation results are presented in the form of corrections to the characteristics of a free jet, taking into account the influence of longitudinal constraint. It is found that influence of Archimede’s buoyant force on the temperature distribution along the length of non-isothermal jet is inconsequential. Dependence of dimensionless temperature on the jet axis of dimensionless length of the room of the coordinate x̄ is determined. The results can be used in calculation of airflow circulation in different purpose air-conditioned rooms.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

Sign in / Sign up

Export Citation Format

Share Document