Stagnation Line and Upwash Formation of Two Impinging Jets

AIAA Journal ◽  
1981 ◽  
Vol 19 (10) ◽  
pp. 1286-1293 ◽  
Author(s):  
M. J. Siclari ◽  
W. G. Hill ◽  
R. C. Jenkins
Keyword(s):  
Impinging Jets ◽  
Stagnation Line

Convective Heat Transfer Enhancement Due to Intermittency in an Impinging Jet

1993 ◽  
Vol 115 (1) ◽  
pp. 91-98 ◽  
Author(s):  
D. A. Zumbrunnen ◽  
M. Aziz
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Stagnation Line ◽  
High Heat Transfer ◽  
Short Period

An experimental investigation has been performed to study the effect of flow intermittency on convective heat transfer to a planar water jet impinging on a constant heat flux surface. Enhanced heat transfer was achieved by periodically restarting an impinging flow and thereby forcing renewal of the hydrodynamic and thermal boundary layers. Although convective heat transfer was less effective during a short period when flow was interrupted, high heat transfer rates, which immediately follow initial wetting, prevailed above a threshold frequency, and a net enhancement occurred. Experiments with intermittent flows yielded enhancements in convective heat transfer coefficients of nearly a factor of two, and theoretical considerations suggest that higher enhancements can be achieved by increasing the frequency of the intermittency. Enhancements need not result in an increased pressure drop within a flow system, since flow interruptions can be induced beyond a nozzle exit. Experimental results are presented for both the steady and intermittent impinging jets at distances up to seven jet widths from the stagnation line. A theoretical model of the transient boundary layer response is used to reveal parameters that govern the measured enhancements. A useful correlation is also provided of local heat transfer results for steadily impinging jets.

Computational Investigations of Flow and Heat Transfer on an Effused Concave Surface With a Single Row of Impinging Jets for Different Exit Configurations

2009 ◽  
Author(s):  
M. Ashok Kumar ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Computational Study ◽  
Impinging Jets ◽  
Concave Surface ◽  
Local Enhancement ◽  
Stagnation Line ◽  
Single Row ◽  
Air Jets ◽  
Flow And Heat Transfer

A computational study is reported on flow and heat transfer from single row of circular air jets impinging on a concave surface with either one or two rows of effusion holes and without effusion holes. The effects of arrangement of jet orifices and effusion holes, spent air exit closure configurations, H/D ratio and jet Reynolds number are investigated. The pressure distribution is higher for the configuration with the air exit only through effusion holes. At higher Reynolds number, three peaks in local Nusselt number are identified and explained. Among the cases tested, the configuration with single row of inline effusion holes shows the least heat transfer and there is a significant local enhancement in heat transfer along the stagnation line for single row of staggered effusion holes. However, the effect of arrangement is negligible for two rows of effusion holes. Among the configuration tested the case of one edge open exit configuration with single row of staggered effusion holes (Case-C1s) shows higher heat transfer among others.

Stagnation line due to colliding wall jets of two liquid impinging jets on a horizontal surface

2021 ◽  
Vol 33 (4) ◽  
pp. 047112
Author(s):  
Behzad Mohajer ◽  
Anshuman Dey ◽  
Ri Li
Keyword(s):  
Impinging Jets ◽  
Horizontal Surface ◽  
Wall Jets ◽  
Stagnation Line

Mist/Steam Cooling by a Row of Impinging Jets

2001 ◽  
Author(s):  
X. Li ◽  
J. L. Gaddis ◽  
T. Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Cfd Simulation ◽  
Heated Surface ◽  
Impinging Jets ◽  
Stagnation Line ◽  
Round Jets ◽  
Steam Cooling ◽  
The Heat Transfer Coefficient

Closed loop steam has been chosen for cooling airfoils in heavy frame Advanced Turbine Systems (ATS) to improve efficiency. Enhanced cooling by the use of mist is considered to have potential to augment cooling by internal steam alone. Water droplets generally less than 10μm are added to 1.3 bar steam and injected through a row of four discrete round jets onto a heated surface. The Reynolds number is varied from 7500 to 22500 and the heat flux varied from 3.3 to 13.4 kW/m2. The mist increases the heat transfer coefficient along the stagnation line and downstream wanes in about 5 jet diameters. The heat transfer coefficient improves by 50 to 700 percent at the stagnation line for mist concentrations 0.75 to 3.5 percent by weight, depending on conditions. Off-axis maximum cooling occurs in most of the mist/steam flow but not in the steam-only flow. CFD simulation indicates that this off-axis cooling peak is caused by droplets’ interaction with the target walls.

CHARACTERISTIC STUDY ON THE LIKE-DOUBLET IMPINGING JETS ATOMIZATION

1999 ◽  
Vol 9 (3) ◽  
pp. 277-289 ◽  
Author(s):  
Wei-Hsiang Lai ◽  
Wennon Huang ◽  
Tsung-Leo Jiang
Keyword(s):  
Impinging Jets

HOLOGRAPHY EXPERIMENTS IN THE BREAKUP REGION OF A LIQUID SHEET FORMED BY TWO IMPINGING JETS

1995 ◽  
Vol 5 (4-5) ◽  
pp. 387-402 ◽  
Author(s):  
B. S. Kang ◽  
Y. B. Shen ◽  
D. Poulikakos
Keyword(s):  
Impinging Jets ◽  
Liquid Sheet

FLOW STRUCTURE AND HEAT TRANSFER IN MULTIPLE IMPINGING JETS

2016 ◽  
Vol 47 (4) ◽  
pp. 359-382 ◽  
Author(s):  
Nabil Kharoua ◽  
Lyes Khezzar ◽  
Zoubir Nemouchi
Keyword(s):  
Heat Transfer ◽  
Flow Structure ◽  
Impinging Jets
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