scholarly journals Studies on the Flow of Axisymmetric Radialwise Wall Jet on the Impinged Wall by the Annular Impinging Jet

1980 ◽  
Vol 23 (176) ◽  
pp. 217-223 ◽  
Author(s):  
Hiroshi MAKI ◽  
Hikoaki ITO ◽  
Fumitaka SAIGO
Keyword(s):  
Impinging Jet ◽  
Wall Jet

Experimental Study on Fluid Mixing for Evaluation of Thermal Striping in T-Pipe Junction

2002 ◽  
Author(s):  
Minoru Igarashi ◽  
Masaaki Tanaka ◽  
Shigeyo Kawashima ◽  
Hideki Kamide
Keyword(s):  
Temperature Fluctuation ◽  
Velocity Ratio ◽  
Impinging Jet ◽  
Fluid Mixing ◽  
Cold Spot ◽  
Wall Jet ◽  
Fluid Temperature ◽  
Thermochromic Liquid Crystal ◽  
Inflow Condition ◽  
Thermal Striping

A water experiment is performed to investigate thermal striping phenomena in a T-pipe junction which is a typical geometry of fluid mixing. The flow velocity ratio and temperature difference were experimental parameters. The jet form was classified into four patterns; (1) impinging jet, (2) deflecting jet, (3) re-attachment jet and (4) wall jet according to the inflow condition. The parameter experiments showed that the jet form could be predicted by a momentum ratio between the two pipes. The thermochromic liquid crystal sheet showed that a cold spot was formed at the wall surface in the main pipe in the cases of the impinging jet and the wall jet. From the temperature measurement in the fluid, temperature fluctuation intensity was high along the edge of the jet exiting from branch piping. A database of temperature fluctuation and frequency characteristics was established for an evaluation rule of thermal striping in a T-pipe junction.

Performance analysis of different turbulence models in impinging jet cooling

2020 ◽  
Vol 31 (04) ◽  
pp. 2050051
Author(s):  
Shashikant Pawar ◽  
Devendra Kumar Patel
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Transfer Problem ◽  
Impinging Jet ◽  
Experimental Results ◽  
Wall Jet ◽  
Quadratic Formula ◽  
Upward Direction ◽  
Number Formula ◽  
Text Model

The characteristics of heat transfer from a hot wall surface for the oblique impingement of a free turbulent slot jet have been investigated numerically. Different turbulent models — the [Formula: see text]-[Formula: see text], [Formula: see text]-[Formula: see text], SST [Formula: see text]-[Formula: see text], cubic [Formula: see text]-[Formula: see text] and quadratic [Formula: see text]-[Formula: see text] models — are used for the prediction of heat transfer and their results were compared with experimental results reported in the literature. The comparison shows that the [Formula: see text]-[Formula: see text], quadratic [Formula: see text]-[Formula: see text] and SST [Formula: see text]-[Formula: see text] models give more unsatisfactory results for the investigated configuration, while the cubic [Formula: see text]-[Formula: see text] model is capable of predicting the local Nusselt number in wall-jet region only. The [Formula: see text]-[Formula: see text] model exhibits the best agreement with the experimental results in both stagnation and wall-jet regions. Further, the [Formula: see text]-[Formula: see text] model is applied to analyze the obliquely impinging jet heat transfer problem. The parametric effects of the jet inclination ([Formula: see text], [Formula: see text] and [Formula: see text]), jet-to-surface distance ([Formula: see text], 6 and 8), Reynolds number ([Formula: see text], 15[Formula: see text]000 and 20[Formula: see text]000), and turbulent intensity ([Formula: see text], [Formula: see text] and [Formula: see text]) have been presented. The heat transfer on the upward direction is seen to decrease, while that on the downward direction it rises for the increasing angle. It is to be noted that as the value of [Formula: see text] decreases, the point of maximum Nusselt number ([Formula: see text]) displaces toward the upward direction from the geometric center point as well as its value reduces. The shifting of the [Formula: see text] is found to be independent of Re and [Formula: see text] within the range considered for the study.

Oscillation of Impinging Jet with Generation of Acoustic Waves

2002 ◽  
Vol 1 (4) ◽  
pp. 385-402 ◽  
Author(s):  
Y. Sakakibara ◽  
J. Iwamoto
Keyword(s):  
Acoustic Waves ◽  
Pressure Ratio ◽  
Impinging Jet ◽  
Tvd Scheme ◽  
Wall Jet ◽  
Sound Waves ◽  
Convergent Nozzle ◽  
Plate Spacing ◽  
Nozzle Plate ◽  
Jet Oscillation

This paper presents an oscillatory phenomenon of the underexpanded jet which issues from a convergent nozzle and impinges on a flat plate perpendicularly. As the characteristics of the generating noise deeply depend on the oscillation of the impinging jet, the flow field is visualized using the shadowgraph method and the pressure on the plate is measured to classify the oscillation modes for different parameters such as the nozzle pressure ratio and the distance between the nozzle and the plate. For the comparison, the jet is numerically simulated using Total Variation Diminishing (TVD) scheme under the assumption of the non-viscous flow. Simulating the impinging main jet and the radial wall jet on the plate separately, the sound waves propagating around the jet are shown and the frequency of the oscillation for each jet is tested. The wall-jet oscillation which is caused by the small vortices from the main jet occurs at high frequency when the nozzle-plate distance is comparatively small, while the main-jet oscillation induced by the grown vortices are shown to generate at large nozzle-plate spacing and the frequencies under such condition have well-known saw-tooth characteristics. With the correlation of pressure on the plate, three types of the oscillation – axisymmetric mode, whirling mode and non-regular pattern – are shown.

Flow Visualization of Axisymmetric Impinging Jet on a Concave Surface

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Dong Hwan Shin ◽  
Yeonghwan Kim ◽  
Jin Sub Kim ◽  
Do Won Kang ◽  
Jeong Lak Sohn ◽  
...  
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Impinging Jet ◽  
Ambient Air ◽  
Concave Surface ◽  
Small Scale ◽  
Wall Jet ◽  
Entrainment Rate ◽  
Toroidal Vortex ◽  
Axisymmetric Jet

Flow visualization was performed to give a physical insight with vortical structures of an axisymmetric impinging jet on a concave surface. High-speed imaging was employed to get clear images with a laser light sheet illumination. An axisymmetric jet is issued into quasi-ambient air through a straight pipe nozzle with fully-developed velocity profile. A regular vertical pattern of an axisymmetric jet was observed with different flow entrainment rate. While an impinged jet turns to convert a wall jet along a concave surface, the flow interaction between the large-scale toroidal vortex and the concave surface was observed in the transition between the stagnation and wall jet zone. The ring-shaped wall eddies induced from a pair of toroidal vortices were also appeared to diverge into the radial direction along the concave surface. As the jet Reynolds number increases, small-scale vortices can be developed to a large-scale toroidal vortex. The location in which a large-scale toroidal vortex strikes is generally identical to the location where the secondary peak in heat transfer occurs. The frequency of large scale toroidal vortex on concave surface is found to be nearly similar as that of wall jet on flat surface. As the nozzle-to-target spacing (L/D) increases, it becomes shorter due to the loss of jet momentum. The flow behavior of axisymmetric impinging jet on a concave surface can be helpful to design the internal passage cooling for gas turbine blade.

Analysis of an Impinging Two-Dimensional Jet

2005 ◽  
Vol 128 (3) ◽  
pp. 307-310 ◽  
Author(s):  
A. H. Beitelmal ◽  
A. J. Shah ◽  
M. A. Saad
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Analytical Solution ◽  
Flat Plate ◽  
Potential Flow ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Wall Jet ◽  
Two Dimensional ◽  
Stagnation Region

Heat transfer in jet impingement is a complicated phenomenon and a general analytical solution is not available. Typical jet impingement studies are conducted experimentally and best-fit correlations are proposed (Beitelmal, Saad, and Patel [2]; Beitelmal [3]; Beitelmal, Saad, and Patel [4]; Schauer and Eustis [7]; McMurray, Myers, and Uyehara [8], Gardon and Akfirat [9]). Separate solutions for the stagnation region and the wall jet region are then combined to determine the overall heat transfer solution for the impinging jet. In this paper, stagnation and wall jet region solutions for a two-dimensional jet normally impinging on a flat surface are developed using heat transfer relations available in the literature. These solutions are analyzed and compared to previous experimental results (Beitelmal, Saad, and Patel [2]; Beitelmal [3]). The potential flow assumption is used for the fluid dynamics analysis at the stagnation region. For the wall jet region, a comparison was achieved through consideration of the classical analytical solution for parallel flow over a flat plate. Analytical solutions as well as semiempirical solutions for the stagnation region and the wall jet reported by previous investigators were also considered. Predictions for heat transfer in the stagnation region using potential flow assumptions were found to be accurate to within 20%. For the wall jet region, previous correlations predicted by McMurray, Myers, and Uyehara [8] and Nizou [10] were found to be the most accurate. At large values of x∕D, the heat transfer properties in the wall jet are shown to be very similar to those of a turbulent boundary layer over a flat plate. Such a simplified analysis in different regions of an impinging jet using some basic fluid dynamics assumptions can greatly facilitate a prediction of the local Nusselt number.

scholarly journals Scour formation due to simultaneous circular impinging jet and wall jet

2012 ◽  
Vol 50 (4) ◽  
pp. 395-399 ◽  
Author(s):  
Mojtaba Mehraein ◽  
Masoud Ghodsian ◽  
Anton J. Schleiss
Keyword(s):  
Impinging Jet ◽  
Wall Jet

Very Large Eddy Simulation of Flow and Heat Transfer in a Pulsating Impinging Jet

2020 ◽  
Author(s):  
Fangyuan Liu ◽  
Junkui Mao ◽  
Xingsi Han ◽  
Zhaoyang Xia
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Large Eddy Simulation ◽  
Impinging Jet ◽  
Core Region ◽  
Wall Jet ◽  
The Core ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Pulsating Jets

Abstract The steady impinging jets applied in turbomachine have been comprehensively studied but the pulsating jets still need to be further researched. The flow field and heat transfer characteristics of pulsating impinging jet impinging on a flat plate have been simulated using the improved very large eddy simulation established with SST k–ω model. Two time-mean Reynolds numbers (6,000 and 23,000) in the conditions of frequency = 10Hz and steady state at the constant jet–to–surface distance (6D) were considered. The velocity, vortices, and Nusselt number distributions on the plate surface were investigated to emphasize on the vortex structures in the flow and its relation to the heat transfer. The investigation has revealed the advantage of the improved very large eddy simulation for predicting the dynamical generating process of flow structures in pulsating jets. Calculated results showed pairs of vortices were organized and induced from the jet exit, and propagated along with the jet region periodically. The vortices grew with the entrainment towards the ambient fluid and resulted in accelerated interaction in the wall jet region. Meanwhile, the vortices had strong interaction with the core region and weakened velocity in the core region. Results showed that the time–mean local Nusselt number of pulsating jet was lower in the stagnation region at both investigated Re numbers but not reduced in the wall jet region.

Effect of pulsation on the wall jet flow in the near region of an impinging jet

2021 ◽  
Vol 62 (8) ◽  
Author(s):  
Abhishek Mishra ◽  
Harekrishna Yadav ◽  
Lyazid Djenidi ◽  
Amit Agrawal
Keyword(s):  
Impinging Jet ◽  
Jet Flow ◽  
Wall Jet ◽  
Wall Jet Flow
Sign in / Sign up

Export Citation Format

Share Document