121 Characteristics of Velocity Fluctuation near Trailing Edge of Rotor Blade of Axial Flow Fan

2014 ◽  
Vol 2014.67 (0) ◽  
pp. _121-1_-_121-2_
Author(s):  
Kazuki HOSOKAI ◽  
Naoki ANDO ◽  
Hiromitsu HAMAKAWA ◽  
Eru KURIHARA
Keyword(s):  
Velocity Fluctuation ◽  
Rotor Blade ◽  
Axial Flow ◽  
Axial Flow Fan ◽  
Trailing Edge

213 Relation between Aerodynamic Noise and Velocity Fluctuation around Rotor Blade of Axial Flow Fan

2012 ◽  
Vol 2012.65 (0) ◽  
pp. 67-68
Author(s):  
Masatomo Shiotuki ◽  
Taro Nakamura ◽  
Hiromitsu Hamakawa ◽  
Eru Kurihara
Keyword(s):  
Velocity Fluctuation ◽  
Rotor Blade ◽  
Axial Flow ◽  
Aerodynamic Noise ◽  
Axial Flow Fan

Relationship between Aerodynamic Noise and Velocity Fluctuation in the Near-wake of Rotor Blade of Axial Flow Fan

2016 ◽  
Vol 2016.26 (0) ◽  
pp. 110
Author(s):  
Hiromitsu HAMAKAWA ◽  
Yuta YAMAUCHI ◽  
Kaisei ODA ◽  
Eru KURIHARA ◽  
Hidechito HAYASHI
Keyword(s):  
Velocity Fluctuation ◽  
Rotor Blade ◽  
Axial Flow ◽  
Aerodynamic Noise ◽  
Axial Flow Fan ◽  
Near Wake

Vortex Shedding From Trailing Edge of Rotor Blade of Axial Flow Fan at Design Operating Condition

2015 ◽  
Author(s):  
Hiromitsu Hamakawa ◽  
Kaisei Oda ◽  
Yuta Asai ◽  
Kazuki Hosokai ◽  
Eru Kurihara ◽  
...  
Keyword(s):  
Vortex Shedding ◽  
Velocity Fluctuation ◽  
Rotor Blade ◽  
Time Lag ◽  
Axial Flow ◽  
Rotational Axis ◽  
Trailing Edge ◽  
Velocity Fluctuations ◽  
Operating Condition ◽  
Karman Vortex

In the present paper the attention is focused on the vortex shedding from the trailing edge of the rotor blade at the design operating condition. We measured the relative velocity, the turbulence intensity, the spectrum of velocity fluctuation and the in-phase velocity fluctuation near the trailing edge along the blade span. The time variations of amplitude of velocity fluctuations from 1500 Hz to 1900 Hz in the wake of the suction and pressure side of the trailing edge are out of phase with each other simultaneously at the mid span region. Karman vortices were formed in the near wake of the trailing edge of rotor blade intermittently. As the distance between two measured locations along the blade span increased, the in-phase rate of two velocity fluctuations decreased. This rate became maximum value at the time lag of 0 s. As the measured radius of the moved sensor increased, the time lag decreased. The rotational axis of Karman vortex inclined for the trailing edge of rotor blade.

scholarly journals The influence of axial-flow fan trailing edge structure on internal flow

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881174
Author(s):  
Weijie Zhang ◽  
Jianping Yuan ◽  
Banglun Zhou ◽  
Hao Li ◽  
Ye Yuan
Keyword(s):  
Numerical Simulation ◽  
Low Frequency ◽  
Axial Flow ◽  
Internal Flow ◽  
Axial Flow Fan ◽  
Trailing Edge ◽  
Edge Structure ◽  
Blade Loading ◽  
Wideband Noise ◽  
Fluctuation Amplitude

Axial-flow fan with advantages such as large air volume, high head pressure, and low noise is commonly used in the work of air-conditioner outdoor unit. In order to investigate the internal flow mechanism of the axial-flow fan with different trailing edge structures of impellers, four kinds of impellers were designed, and numerical simulation and experiment were deployed in this article. The pressure distribution on the blades surface and distribution of vorticity in impellers were obtained using numerical simulation. Distribution of blade loading and velocity at the circumference are discussed. The relationship between the wideband noise and the trailing edge was established based on the experiment results. The results show that after the optimization of the trailing edge structure, the distribution of vorticity near the trailing edge of the blade is more uniform, especially at the trailing edge of 80% of the chord length of the suction surface. From the blade height position of 70% to the impeller tip, the pressure on the surface rapidly increases due to the tip vortex and the vortex shedding on the blade edge occurred in the top region of impeller. The pressure fluctuation amplitude at the trailing edge structure of the tail-edge optimization structure is smaller. In the distribution of blade loading, the three tail-edge optimization structures have smaller pressure fluctuations and pressure differences at the trailing edge structure. It is extremely important to control the fluctuation amplitude at the trailing edge. The amplitude of low-frequency sound pressure level of optimizing the trailing edge structure decreases obviously in the range of 50–125 Hz, and the optimization structure of trailing edge has an obvious effect on low-frequency wideband noise.

scholarly journals Correlation between Aerodynamic Noise and Velocity Fluctuation of Tip Leakage Flow of Axial Flow Fan

2012 ◽  
Vol 02 (04) ◽  
pp. 228-234
Author(s):  
Hiromitsu Hamakawa ◽  
Masatomo Shiotsuki ◽  
Takaaki Adachi ◽  
Eru Kurihara
Keyword(s):  
Velocity Fluctuation ◽  
Axial Flow ◽  
Aerodynamic Noise ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Axial Flow Fan ◽  
Tip Leakage

Performance Improvement on Axial-Flow Fan by Imposing Proper Frame Ribs

2014 ◽  
Vol 598 ◽  
pp. 129-134
Author(s):  
Sheam Chyun Lin ◽  
Fu Yin Wang ◽  
Cheng Ju Chang ◽  
Hung Cheng Yen ◽  
Yung Jen Cheng
Keyword(s):  
Performance Improvement ◽  
Rotor Blade ◽  
High Performance ◽  
Axial Flow ◽  
Tip Clearance ◽  
Geometrical Parameters ◽  
Axial Flow Fan ◽  
Design Guideline ◽  
Fan Performance ◽  
Air Passage

Generally, most research attempts on the axial-flow fan focus on optimizing rotor blade and tip clearance to enhance its aerodynamic and acoustic performances. Few efforts aim at finding out the appropriate frame rib, which is a supporting and vital part within the air passage and thus has significant influence on the turbulent flow near the blade trailing edge. Therefore, this study intends to investigate the geometrical parameters of the frame rib systematically by using an integrated scheme, which consists of numerical simulation, mockup fabrication, and experimental verification. At first, a high-performance fan (90×90×38 mm3) is constructed to serve as the sample fan for this investigation. Then three geometrical sections (triangle, cylinder, and arc) of frame rib are examined systematically to provide a design guideline on utilizing the appropriate frame rib for enhancing the fan performance.

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