Nature of convection-stabilized DC arcs in dual-flow nozzle geometry. I. The cold flow field and DC arc characteristics

1990 ◽  
Vol 18 (1) ◽  
pp. 91-101 ◽  
Author(s):  
I. Serbetci ◽  
H.T. Nagamatsu
Keyword(s):  
Flow Field ◽  
Nozzle Geometry ◽  
Cold Flow ◽  
Arc Characteristics ◽  
Dc Arc

scholarly journals Sensitivity analysis of FDA´s benchmark nozzle regarding in vitro imperfections - Do we need asymmetric CFD benchmarks?

2020 ◽  
Vol 6 (3) ◽  
pp. 78-81
Author(s):  
Michael Stiehm ◽  
Christoph Brandt-Wunderlich ◽  
Stefan Siewert ◽  
Klaus-Peter Schmitz ◽  
Niels Grabow ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
In Silico ◽  
Nozzle Geometry ◽  
Geometrical Imperfection ◽  
Custom Made ◽  
Inlet Conditions ◽  
Silicone Model ◽  
Bench Testing

AbstractModern technologies and methods such as computer simulation, so-called in silico methods, foster the development of medical devices. For accelerating the uptake of computer simulations and to increase credibility and reliability the U.S. Food and Drug Administration organized an inter-laboratory round robin study of a generic nozzle geometry. In preparation of own bench testing experiment using Particle Image Velocimetry, a custom made silicone nozzle was manufactured. By using in silico computational fluid dynamics method the influence of in vitro imperfections, such as inflow variations and geometrical deviations, on the flow field were evaluated. Based on literature the throat Reynolds number was varied Rethroat = 500 ± 50. It could be shown that the flow field errors resulted from variations of inlet conditions can be largely eliminated by normalizing if the Reynolds number is known. Furthermore, a symmetric imperfection of the silicone model within manufacturing tolerance does not affect the flow as much as an asymmetric failure such as an unintended curvature of the nozzle. In brief, we can conclude that geometrical imperfection of the reference experiment should be considered accordingly to in silico modelling. The question arises, if an asymmetric benchmark for biofluid analysis needs to be established. An eccentric nozzle benchmark could be a suitable case and will be further investigated.

Influence of the over-fire air angle on the flow field in a down-fired furnace determined by a cold-flow experiment

Fuel ◽  
2011 ◽  
Vol 90 (3) ◽  
pp. 997-1003 ◽  
Author(s):  
Feng Ren ◽  
Zhengqi Li ◽  
Zhichao Chen ◽  
Zhenxing Xu ◽  
Guohua Yang
Keyword(s):  
Flow Field ◽  
Cold Flow ◽  
Flow Experiment

Influence of Primary and Secondary Flow Interaction on the Near Flow Field Mixing in an Enclosed Space

2006 ◽  
Author(s):  
Ijaz M. Khan ◽  
Tony Gilbert ◽  
Mostafa Barigou
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Air Entrainment ◽  
Streamwise Velocity ◽  
Nozzle Geometry ◽  
Turbulence Characteristics ◽  
Mass Entrainment ◽  
Diffusion Characteristics ◽  
Velocity Decay ◽  
Enclosed Space

This paper presents the influence of an induction diffuser ports on a turbulent jet and its effect on the axial mean streamwise velocity decay, mass entrainment, turbulence characteristics and the temperature distribution in the near flow field of an enclosed numerical space. Convergence of the steady state simulations is achieved by RNG kappa-epsilon turbulence model. Comparisons of the axial mean streamwise velocity decay, turbulence characteristics and the temperature distribution in an enclosed space are reported for JETs (Jet Environmental Techniques) nozzle, and another similar simulation was conducted for an induction diffuser box with open ports at specific positions to evaluate its performance. The numerical analysis was validated by prototype experiments using the JETs nozzle geometry in a test room 11 m in length, 5.5 m wide and 2.5 m high. The measurement of the streamwise velocity and temperature distribution was measured inside the room on a grid with the help of a hotwire anemometer and digital thermometer, respectively. From the analysis of the data, it was found that the near flow field air entrainment and diffusion characteristics of the jet were significantly influenced by the air induction diffuser.

Impact of Mechanical Chevrons on Supersonic Jet Flow and Noise

2009 ◽  
Author(s):  
K. Kailasanath ◽  
Junhui Liu ◽  
Ephraim Gutmark ◽  
David Munday ◽  
Steven Martens
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Near Field ◽  
Supersonic Jet ◽  
Initial Step ◽  
Nozzle Geometry ◽  
Jet Flows ◽  
Flow Conditions ◽  
Nozzle Geometries ◽  
The Impact

In this paper, we present observations on the impact of mechanical chevrons on modifying the flow field and noise emanated by supersonic jet flows. These observations are derived from both a monotonically integrated large-eddy simulation (MILES) approach to simulate the near fields of supersonic jet flows and laboratory experiments. The nozzle geometries used in this research are representative of practical engine nozzles. A finite-element flow solver using unstructured grids allows us to model the nozzle geometry accurately and the MILES approach directly computes the large-scale turbulent flow structures. The emphasis of the work is on “off-design” or non-ideally expanded flow conditions. LES for several total pressure ratios under non-ideally expanded flow conditions were simulated and compared to experimental data. The agreement between the predictions and the measurements on the flow field and near-field acoustics is good. After this initial step on validating the computational methodology, the impact of mechanical chevrons on modifying the flow field and hence the near-field acoustics is being investigated. This paper presents the results to date and further details will be presented at the meeting.

Effect of arc characteristics on the properties of large size diamond wafer prepared by DC arc plasma jet CVD

2013 ◽  
Vol 39 ◽  
pp. 47-52 ◽  
Author(s):  
C.M. Li ◽  
R.H. Zhu ◽  
J.L. Liu ◽  
L.X. Chen ◽  
J.C. Guo ◽  
...  
Keyword(s):  
Plasma Jet ◽  
Arc Plasma ◽  
Arc Characteristics ◽  
Large Size ◽  
Dc Arc
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