Preliminary Investigation Into the Effects of Cross-Flow on Low Reynolds Number Transition

2011 ◽  
Author(s):  
Alejandra Uranga ◽  
Per-Olof Persson ◽  
Mark Drela ◽  
Jaime Peraire
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Preliminary Investigation ◽  
Cross Flow ◽  
Low Reynolds

scholarly journals Investigation of effect on cross-flow heat exchanger with air flow non-uniformity under low Reynolds number

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770808 ◽  
Author(s):  
Kai Shen ◽  
Zhendong Zhang ◽  
Ziqing Zhang ◽  
Youwen Yang
Keyword(s):  
Reynolds Number ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Low Reynolds Number ◽  
Air Flow ◽  
Cross Flow ◽  
Calculation Model ◽  
Flow Heat ◽  
Air Flows ◽  
Low Reynolds

In this study, the theoretical and experimental study of a cross-flow heat exchanger is carried out based on the theory of porous media under low Reynolds number. The accuracy of the mathematical calculation model is verified by experiments. Pressure drop in air side and efficiency of heat exchanger are analyzed with mathematical models of various non-uniform air flows under low Reynolds number. The responses are found influences of air flow non-uniformity on pressure drop and efficiency of heat exchanger have certain rules. The difference in pressure drops between non-uniform air flows and evenly distributed air flows is linearly related to variance [Formula: see text] of non-uniformity. And the increasing rate of resistance energy consumption difference between non-uniform air flows and evenly distributed air flows is approximately linearly related to the relatively non-uniform coefficient squared [Formula: see text] of non-uniformity. The descent range of heat transfer efficiency has exponential relation to the relatively non-uniform coefficient [Formula: see text].

The Effects of the Synthetic Jet on the Mixing Promotion in Low Reynolds Number

2007 ◽  
Author(s):  
Masashi Higashiura ◽  
Koichi Inose ◽  
Masahiro Motosuke ◽  
Shinji Honami
Keyword(s):  
Reynolds Number ◽  
Flow Visualization ◽  
Static Pressure ◽  
Low Reynolds Number ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Vortex Pair ◽  
Synthetic Jet ◽  
The Cross ◽  
Low Reynolds

The present paper describes a synthetic jet interaction with the cross flow in low Reynolds number condition by flow visualization and the wall static pressure measurements. The primary focus of the current study is to examine the possibility on the interaction of the synthetic jet with the cross flow in low Reynolds number viscous dominant flow. The low bulk velocity of the cross flow is set in a small scale of the wind tunnel with a high aspect ratio. A wide range of Reynolds number based on the tunnel height and the bulk velocity is covered. The flow visualization at Reynolds number of 1,000 is conducted in X-Y and Y-Z planes to clarify the development of the interaction process in the downstream. Both the time averaged and phase averaged wall static pressure were obtained downstream of the jet injection. The synthetic jet has a diameter of 0.5 mm and a frequency of 100 to 400 Hz. The penetration of the jet in the cross flow depends on the jet velocity ratio, and the deepest penetration occurs at the phase of π/2 at the highest jet velocity ratio. The counter rotating longitudinal vortex pair is generated even in low Reynolds number and can be observed at 100d downstream from the injection. The vortex pair shows the up-wash motion at the center of the jet core and the down-wash motion at the outsides of the jet. For the synthetic jet in cross flow, the fluctuated wall static pressure is increased, and the wall static pressure has similar frequency to the synthetic jet.

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