scholarly journals Wake-Body Interaction Noise Simulated by the Coupling Method Using CFD and BEM

2020 ◽  
Author(s):  
Masaaki Mori
Keyword(s):  
Heat Exchanger ◽  
Vortex Shedding ◽  
Peak Frequency ◽  
Flow Patterns ◽  
Coupling Method ◽  
Sound Generation ◽  
Engineering Applications ◽  
Rotating Blades ◽  
Body Interaction ◽  
Dominant Peak

In many engineering applications, obstacles often appear in the wake of obstacles. Vortices shed from an upstream obstacle interact with downstream obstacle and generate noise, for example blades in a turbomachinery, tubes in a heat exchanger, rotating blades like a helicopter and wind turbine and so on. This phenomenon is called wake-body interaction or body-vortex interaction (BVI). The rod-airfoil and airfoil-airfoil configurations are typical models for the wake-body interaction. A rod and an airfoil are immersed upstream of the airfoil. In this chapter, we review the noise mechanism generated by the wake-body interaction and show the numerical results obtained by the coupling method using commercial CFD and acoustic BEM codes. The results show that depending on the spacing between the rod or airfoil and the airfoil, the flow patterns and noise radiation vary. With small spacing, the vortex shedding from the upstream obstacle is suppressed and it results in the suppression of the sound generation. With large spacing, the shear layer or the vortices shed from the upstream obstacle impinge on the downstream obstacle and it results in the large sound generation. The dominant peak frequency of the generated sound varies with increase in the spacing between the two obstacles.

Wake-body interaction Noise Simulations by Coupling CFD and BEM

2021 ◽  
Vol 263 (1) ◽  
pp. 5360-5371
Author(s):  
Masaaki Mori
Keyword(s):  
Heat Exchanger ◽  
Vortex Shedding ◽  
Peak Frequency ◽  
Vortex Interaction ◽  
Sound Generation ◽  
Rotating Blades ◽  
Body Interaction ◽  
Noise Radiation ◽  
Dominant Peak ◽  
Small Spacing

In many engineering applications, the wake-body interaction or body-vortex interaction (BVI) occurs. In the wake-body interaction, vortices shed from an upstream obstacle interact with downstream obstacle and generate noise, for example blades in a turbomachinery, tubes in a heat exchanger, rotating blades like a helicopter and wind turbine and so on. The rod-airfoil and airfoil-airfoil configurations are typical models for the wake-body interaction. A rod and an airfoil are immersed upstream of the airfoil. In this paper, we reviewed the noise mechanism generated by the wake-body interaction and show the numerical results obtained by the coupling method using commercial CFD and acoustic BEM codes. The results shows that depending on the spacing between the rod or airfoil and the airfoil, the flow patterns and noise radiation vary. With small spacing, the vortex shedding from the upstream obstacle is suppressed and it results in the suppression of the sound generation. With large spacing, the shear layer or the vortices shed from the upstream obstacle impinge on the downstream obstacle and it results in the large sound generation. The dominant peak frequency of the generated sound varies with increasing of the spacing between the two obstacles.

Study on Evaluation of Sound Speed in Duct With Tube Banks

2010 ◽  
Author(s):  
Kunihiko Ishihara
Keyword(s):  
Heat Exchanger ◽  
Resonance Frequency ◽  
Vortex Shedding ◽  
Sound Speed ◽  
Flow Direction ◽  
Fem Analysis ◽  
The Self ◽  
Resonance Phenomenon ◽  
Acoustic Characteristics ◽  
Tube Banks

As tube banks are set in a duct in a boiler and a heat exchanger, the resonance phenomenon or the self sustained tone are generated due to the interference between vortex shedding and the acoustic characteristics of the duct. It is necessary to know the resonance frequency of the duct, namely sound speed, for avoiding any trouble that may arise. In general, it is said that the sound speed decreases in the duct with tube banks and an evaluation formula is given. However, this formula is often used for the perpendicular direction of the flow. We wanted to know whether this formula would be able to be used for the flow direction and for various arrays of patterns or not. In this paper, the applicability of this expression is discussed by using FEM analysis and experiments.

On aerodynamic noise generation from vortex shedding in rotating blades

1992 ◽  
Vol 155 (2) ◽  
pp. 317-324 ◽  
Author(s):  
B.T. Martin ◽  
D.A. Bies
Keyword(s):  
Vortex Shedding ◽  
Aerodynamic Noise ◽  
Noise Generation ◽  
Rotating Blades

Wake interference of a row of normal flat plates arranged side by side in a uniform flow

1986 ◽  
Vol 164 ◽  
pp. 1-25 ◽  
Author(s):  
Masanori Hayashi ◽  
Akira Sakurai ◽  
Yuji Ohya
Keyword(s):  
Vortex Shedding ◽  
Flow Patterns ◽  
Water Tank ◽  
Flat Plates ◽  
Wind Tunnel Experiments ◽  
Wake Interference ◽  
Gap Flow ◽  
Flow Directions ◽  
Stable Flow ◽  
Plate Width

The wake characteristic of groups of normal flat plates, consisting of two, three, or four plates placed side by side with slits in between, have been investigated experimentally. When the ratio of the slit width to the plate width (slit ratio) was small, the gap flows were observed to be biased either upward or downward in a stable way, leading to multiple, stable flow patterns for a single slit-ratio value. Some regularities were recognized in the gap-flow directions and the appearance of the flow patterns. The plates on the biased side showed high drag and regular vortex shedding, while those on the unbiased side showed the opposite. The origin of the biased flow has also been investigated with water-tank experiments, numerical calculations and wind-tunnel experiments. The-results showed that the origin of biasing is strongly related to the vortex shedding of each plate of a row.

scholarly journals PIV Investigations of Flow Patterns in the Entrance Configuration of Plate-fin Heat Exchanger

2006 ◽  
Vol 14 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Jian WEN ◽  
Yanzhong LI ◽  
Aimin ZHOU ◽  
Yansong MA
Keyword(s):  
Heat Exchanger ◽  
Flow Patterns

Effect of Tube Spacing on the Vortex Shedding Characteristics of Laminar Flow Past an Inline Tube Array

2008 ◽  
Author(s):  
C. Liang ◽  
X. Luo ◽  
G. Papadakis
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Unstructured Grid ◽  
Flow Patterns ◽  
Instantaneous Flow ◽  
Flow Past ◽  
Recirculation Zones ◽  
Shedding Frequency ◽  
Drag And Lift ◽  
Lift And Drag

The effect of tube spacing on the vortex shedding characteristics and fluctuating forces in an inline tube array is examined. The array consists of 6 cylinders in tandem, the examined Reynolds number is 100 and the flow is laminar. The numerical methodology and the code employed to solve the equations in an unstructured grid are validated against available results from the literature for the flow past two cylinders in tandem. Computations are then performed for the 6 row inline bank for 8 pitch-to-diameter ratios s ranging from 2.1 to 4. The instantaneous flow patterns are visualised for different spacings and the lift and drag coefficients for all cylinders are recorded and analysed. At the smallest spacing examined (s = 2.1) there are five stagnant and symmetric recirculation zones and weak vortex shedding activity occurs behind the last cylinder only. As s increases, the symmetry of the recirculation zones breaks leading to vortex shedding. This process progressively moves upstream, so that for s = 4 there is clear shedding for every row. The shedding frequency behind each cylinder is the same and increases with tube spacing. A spacing region between 3d and 3.6d is identified, within which rms drag and lift coefficients attain maximum values. This behaviour is explained with the aid of instantaneous flow patterns.

Anti-freezing prediction model for different flow patterns of air-cooled heat exchanger

2020 ◽  
Vol 153 ◽  
pp. 119656
Author(s):  
Weijia Wang ◽  
Yanqiang Kong ◽  
Fengli Wang ◽  
Lijun Yang ◽  
Yuguang Niu
Keyword(s):  
Heat Exchanger ◽  
Prediction Model ◽  
Flow Patterns ◽  
Air Cooled Heat Exchanger
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