scholarly journals Experimental investigation of five parallel plane jets with variation of Reynolds number and outlet conditions

2018 ◽  
Vol 180 ◽  
pp. 02018 ◽  
Author(s):  
Tomas Daubner ◽  
Jens Kizhofer ◽  
Mircea Dinulescu
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Near Field ◽  
Parallel Plane ◽  
Nozzle Geometry ◽  
Channel Height ◽  
Equivalent Diameter ◽  
Free Atmosphere ◽  
Single Plane ◽  
Plane Jets

This article describes an experimental investigation in the near field of five parallel plane jets. The study applies 2D Particle Image Velocimetry (PIV) for ventilated and unventilated jets, where ventilated means exiting into a duct with expansion ratio 3.5 and unventilated means exiting to the free atmosphere. Results are presented for Reynolds numbers 1408, 5857 and 10510. The Reynolds number is calculated for the middle channel and is based on the height of the nozzle (channel) equivalent diameter 2h. All characteristic regions of the methodology to describe multiple interacting jets are observed by the PIV measurements - converging, merging and combined. Each of the five parallel channels has an aspect ratio of 25 defined as nozzle width (w) to height (h). The channels have a length of 185 times the channel height guaranteeing a fully developed velocity profile at the exit from the channel. Spacing between the single plane jets is 3 times the channel height. The near field of multiple mixing jets is depended on outlet nozzle geometry. Blunt geometry of the nozzle was chosen (sudden contraction).

Numerical Study of Two-Dimensional Turbulent Jets

2006 ◽  
Author(s):  
Tarek Abdel-Salam ◽  
Gerald Micklow ◽  
Keith Williamson
Keyword(s):  
Reynolds Number ◽  
Numerical Analysis ◽  
Numerical Study ◽  
Turbulent Jets ◽  
Parallel Plane ◽  
Two Dimensional ◽  
Reattachment Point ◽  
Wall Angle ◽  
Plane Jets ◽  
Turbulent Plane

The current study reports numerical analysis of turbulent jets. Effects of various parameters on the characteristics of two-dimensional turbulent plane parallel and offset jets are investigated. The emphasis is put on the effect of the wall angle and nozzle width on the location merging and the combining points. The flowfield under consideration are two-parallel plane jets and offset jets issued from plane wall. Four angles and three values of the nozzle width are used. Also, different values of Reynolds number between 9000 and 39000 have been examined. It is noted that the wall angle and the nozzle width linearly affect the location of the merging and the combining points, while Reynolds number plays no role in their location. The effect of the wall angle on the reattachment point is found to be non linear.

Experimental-Numerical Analysis of Turbulent Incompressible Isothermal Jets

2017 ◽  
Author(s):  
Seyed Sobhan Aleyasin ◽  
Nima Fathi ◽  
Mark Francis Tachie ◽  
Peter Vorobieff ◽  
Mikhail Koupriyanov
Keyword(s):  
Reynolds Number ◽  
Near Field ◽  
Turbulent Transport ◽  
Reynolds Numbers ◽  
Nozzle Geometry ◽  
System Response ◽  
Potential Core ◽  
Turbulence Structures ◽  
Round Jets ◽  
Core Length

An experimental investigation was conducted to study the effects of Reynolds number on mixing characteristics and turbulent transport phenomena in the near and intermediate regions of free equilateral triangular and round jets issuing from modified contoured nozzles (nozzles with sharp linear contractions). Detailed velocity measurements were made using a particle image velocimetry at Reynolds numbers of 6000, 10000, 13800 and 20000. Computational fluid dynamics (CFD) was also applied to understand the flow behaviors in different Reynolds numbers. We applied standard k-ε turbulence model in an axisymmetric domain to conduct the numerical simulation of the round jet cases. The potential core length was the system response quantity to evaluate our simulation against the experimental results. The geometrical comparative study shows enhanced mixing in the near field of the triangular jets compared to the round jets, regardless of Reynolds number. This conclusion is supported by shorter potential core length and faster growth of turbulence intensity on the centerline of the triangular jets. The obtained data in the round jets exhibit that the jet at the lowest Reynolds number has the most effective mixing with the ambient fluid, while increase in Reynolds number reduces the mixing performance. In the triangular jets almost there is no Reynolds number effect on the measured quantities including the length of the potential core, the decay rate and the axis-switching locations. The results revealed that the asymptotic values of the turbulence intensities on the jet centerline are not only independent of the Reynolds number but also they are the same for both the round and triangular jets. Due to the specific shape of the triangular nozzle, a skewed flow pattern is observed in the near field region in the major plane while the jet is absolutely symmetric in the minor plane. The turbulence structures in all the jets studied become larger as streamwise distance increases, while there is no considerable Reynolds number or nozzle geometry effects on the size of the structures on the jet centerline.

Experimental Investigation on Blunt-Edged UTM Delta Wing VFE-2 Configurations at Low Reynolds Number

2018 ◽  
Vol 12 (3) ◽  
pp. 255
Author(s):  
Muhammad Zal Aminullah Daman Huri ◽  
Shabudin Bin Mat ◽  
Mazuriah Said ◽  
Shuhaimi Mansor ◽  
Md. Nizam Dahalan ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Delta Wing ◽  
Low Reynolds Number ◽  
Low Reynolds

scholarly journals Numerical and Experimental Investigation of Phaseless Spherical Near-Field Antenna Measurements

2021 ◽  
pp. 1-1
Author(s):  
Fernando Rodriguez Varela ◽  
Javier Fernandez Alvarez ◽  
Belen Galocha Iraguen ◽  
Manuel Sierra Castaner ◽  
Olav Breinbjerg
Keyword(s):  
Experimental Investigation ◽  
Near Field ◽  
Antenna Measurements

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.

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