scholarly journals The Turbulence Intensity Effect on the Flow Characteristics and Aerodynamics of a Circular Cylinder

2021 ◽  
pp. 901-912
Author(s):  
İlyas KARASU ◽  
Sergen TÜMSE
Keyword(s):  
Circular Cylinder ◽  
Turbulence Intensity ◽  
Flow Characteristics ◽  
Intensity Effect

scholarly journals Airflow Characteristics According to the Change in the Height and Porous Rate of Building Roofs for Efficient Installation of Small Wind Power Generators

2021 ◽  
Vol 13 (10) ◽  
pp. 5688
Author(s):  
Jangyoul You ◽  
Kipyo You ◽  
Minwoo Park ◽  
Changhee Lee
Keyword(s):  
Wind Speed ◽  
Wind Power ◽  
Turbulence Intensity ◽  
Flow Characteristics ◽  
High Porosity ◽  
Power Generators ◽  
Speed Reduction ◽  
Reduction Effect ◽  
Wind Power Generators ◽  
The Impact

In this paper, the air flow characteristics and the impact of wind power generators were analyzed according to the porosity and height of the parapet installed in the rooftop layer. The wind speed at the top was decreasing as the parapet was installed. However, the wind speed reduction effect was decreasing as the porosity rate increased. In addition, the increase in porosity significantly reduced turbulence intensity and reduced it by up to 40% compared to no railing. In the case of parapets with sufficient porosity, the effect of reducing turbulence intensity was also increased as the height increased. Therefore, it was confirmed that sufficient parapet height and high porosity reduce the effect of reducing wind speed by parapets and significantly reducing the turbulence intensity, which can provide homogeneous wind speed during installation of wind power generators.

Free-Stream Turbulence From a Circular Wall Jet on a Flat Plate Heat Transfer and Boundary Layer Flow

1989 ◽  
Vol 111 (1) ◽  
pp. 78-86 ◽  
Author(s):  
R. MacMullin ◽  
W. Elrod ◽  
R. Rivir
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Flow Characteristics ◽  
Surface Profile ◽  
Constant Heat Flux ◽  
Length Scale ◽  
Wall Jet ◽  
Reynolds Analogy ◽  
Free Stream Turbulence

The effects of the longitudinal turbulence intensity parameter of free-stream turbulence (FST) on heat transfer were studied using the aggressive flow characteristics of a circular tangential wall jet over a constant heat flux surface. Profile measurements of velocity, temperature, integral length scale, and spectra were obtained at downstream locations (2 to 20 x/D) and turbulence intensities (7 to 18 percent). The results indicated that the Stanton number (St) and friction factor (Cf) increased with increasing turbulence intensity. The Reynolds analogy factor (2St/Cf) increased up to turbulence intensities of 12 percent, then became constant, and decreased after 15 percent. This factor was also found to be dependent on the Reynolds number (Rex) and plate configuration. The influence of length scale, as found by previous researchers, was inconclusive at the conditions tested.

Numerical Investigation of Inlet Turbulence Intensity Effect on a Bluff-Body Stabilized Flame at Near Flame Blow-Off Conditions

2020 ◽  
Author(s):  
Amir Ali Montakhab ◽  
Benjamin Akih Kumgeh
Keyword(s):  
Boundary Conditions ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Bluff Body ◽  
Chemical Species ◽  
Simulation Method ◽  
Intensity Effect ◽  
Flame Instability ◽  
Eddy Simulation ◽  
Lean Conditions

Abstract This paper investigates the effects of the inlet turbulence intensity (ITI) on the dynamics of a bluff-body stabilized flame operating very close to its blow-off condition. This work is motivated by the understanding that more stringent regulations on combustion-generated emission have forced the industry to design combustion systems that operate at very fuel-lean conditions. Combustion at very lean conditions, however, induces flame instability that can ultimately lead to flame extinction. The dynamics of the flame at lean conditions can therefore be very sensitive to boundary conditions. Here, a numerical investigation is conducted using Large Eddy Simulation method to understand the flame sensitivity to inlet turbulence intensity. Combustion is accounted for through the transport of chemical species. The sensitivity to inlet turbulence is assessed by carrying out simulations in which the inlet turbulence is varied in increments of 5%. It is observed that while the inlet intensity of 5% causes blow-off, further increased to 10% preserves a healthy flame on account of greater heat release arising from greater and balanced entrainment of combustible mixtures into the flame zone just behind the bluff-body. This balanced stabilization is again lost as the inlet turbulence intensity is further increased to 15%. Since experimental data pertaining to the topic of this paper are rare, the reasonableness of the combination of models is first checked by validating Volvo propane bluff-body flame, whereby reasonable agreement is observed. This study will advance our understanding of the sensitivity of bluff-body flames to boundary conditions specifically to the inlet turbulent boundary condition at near critical blow-off flame conditions.

Effects of Freestream Turbulence Intensity on the Flow Past a Circular Cylinder

2004 ◽  
Vol 28 (8) ◽  
pp. 953-960
Author(s):  
Jong-Yeon Hwang ◽  
Kyung-Soo Yang ◽  
Sungsu Lee ◽  
Joon Sik Lee ◽  
Sangsan Lee
Keyword(s):  
Circular Cylinder ◽  
Turbulence Intensity ◽  
Freestream Turbulence ◽  
Flow Past
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