Investigation on Unstable Pressure Distribution of an Axial Fan Blade with Difference of Setting Angle and Chord Length

2020 ◽  
Vol 13 (2) ◽  
pp. 336-347 ◽  
Author(s):  
Yong-In Kim ◽  
Seul-Gi Lee ◽  
Sang-Yeol Lee ◽  
Hyeon-Mo Yang ◽  
Sung Kim ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Chord Length ◽  
Axial Fan ◽  
Setting Angle ◽  
Fan Blade

Surface Coating Effect on Protection of Icing for Axial Fan Blade

2011 ◽  
Author(s):  
Takeshi Murooka ◽  
Shinichirou Shishido ◽  
Riho Hiramoto ◽  
Takakazu Minoya
Keyword(s):  
Surface Coating ◽  
Axial Fan ◽  
Fan Blade

Evaluation of Effects of Different Design Parameters on Axial Fan Performance Using CFD

2015 ◽  
Author(s):  
Racheet Matai ◽  
Savas Yavuzkurt
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Chord Length ◽  
Design Parameters ◽  
Axial Fan ◽  
Blade Length ◽  
Resistor Networks ◽  
Mass Flow Rates

The performance of an industrial fan was simulated using CFD and results were compared with the experimental data. The fan is used to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. It has a diameter of 24 inches (0.6096m) and rotates at different speeds ranging from 2500 to 3900 RPM depending on the requirements. CFD simulation results were also verified by simulating performance of the same fan at different speeds and comparing the results with what was expected from fan affinity laws. The CFD results matched almost exactly (with ∼0.2% difference for pressure at a given flow rate) with the performance being predicted by the affinity laws. The effect of variation of different parameters such as the blade length, number of blades, and blade chord length was studied. Increasing the blade length at the same RPM increased the mass flow rate (by ∼17%) for the same pressure. Increasing the chord length while keeping the same number of blades, at a given RPM, made the performance curve (pressure versus flow rate, i.e. PV curve) steeper and blades stalled at a higher mass flow rate (8.77 kg/sec compared to the previous 8.44 kg/sec). For the same total blade surface area, less number of blades with longer chords stalled at lower mass flow rates (9.22 kg/sec for a 33% shorter chord and 36 blades compared to 8.3 kg/sec for the original rotor which had 24 blades).

A Ring Silencer Design for Reducing Noise of Axial Fan

2003 ◽  
Vol 03 (03) ◽  
pp. L259-L264
Author(s):  
Jian-Da Wu ◽  
Mingsian R. Bai
Keyword(s):  
Helmholtz Resonator ◽  
Boundary Region ◽  
Acoustic Analogy ◽  
Axial Fan ◽  
Noise Sources ◽  
Fan Noise ◽  
Fluctuating Pressure ◽  
Axial Fans ◽  
Fan Blade ◽  
Broadband Frequency

In this paper, a ring silencer design for reducing the noise of axial fans is presented. The noise sources on axial fans are usually caused by the fluctuating pressure distribution on the surface of fan blade. Most of the sources are near the trailing edge of blades or boundary region of blades. The ideation of proposed design is based on the principle of Helmholtz resonator for reducing the noise around the fan. The electro-acoustic analogy of this design is presented and simply discussed. Experimental measurement is carried out to evaluate the proposed design for reducing the axial fan noise. The result of experiment indicated that the ring silencer achieved 17 dB in blade passing frequency and 10 dB in other broadband frequency of power spectrum level.

Fan Blade Design Methods: Cascade Versus Isolated Airfoil Approach — Experimental and Numerical Comparison

2016 ◽  
Author(s):  
Stefano Castegnaro
Keyword(s):  
Reynolds Numbers ◽  
Medium Size ◽  
Numerical Comparison ◽  
Blade Design ◽  
Axial Fan ◽  
Local Flow ◽  
Flow Features ◽  
Fan Blade ◽  
Mixed Approach ◽  
Cfd Analyses

Both cascade and isolated airfoil methods are considered valid in axial fan blade design, for high (σ≳1) and low (σ≲0.7) solidities respectively. For bladings that feature intermediate solidities the modified isolated approach is commonly employed. This method uses isolated airfoil data, with proper adjustments to take into account multiplane interference effects. Contrarily, the literature does not refer about modifications of the cascade approach to design medium solidity fans. Such method would use cascade data, properly adjusted for the blade sections at lower solidities. Thus, with the aim of comparing these two opposite design approaches (modified cascade versus modified isolated) for medium solidity blades, two free-vortex blading were designed for a 315 mm rotor-only axial fan and experimentally tested. CFD analyses were performed as well to obtain the local flow features. NACA-65 series airfoils were employed, as both cascade and isolated data are available for chord Reynolds numbers typical of axial fans applications. Results highlight the differences between the two approaches. Finally, a mixed approach that employs both isolated and cascade data is suggested as the most accurate one. Moreover, results also show the detrimental effects of the low chord Reynolds numbers on the performance of the blades. This effect should be taken into account in blade design for small-to-medium size machines.

scholarly journals A New Method for Adjusting Setting Angle of Rotor Blade for Axial Fan in Wind Tunnel

2019 ◽  
Vol 37 (3) ◽  
pp. 580-586
Author(s):  
Xiaoli Qu ◽  
Zebin Ren ◽  
Wenguo Yang ◽  
Yuanqiang Luo ◽  
Chenghua Cong
Keyword(s):  
Wind Tunnel ◽  
Flow Velocity ◽  
Test Section ◽  
Rotor Blade ◽  
New Method ◽  
Axial Fan ◽  
Low Speed ◽  
Rotating Speed ◽  
Setting Angle ◽  
Low Speed Wind Tunnel

Combining the fan aerodynamic efficiency with the wind tunnel pressure loss coefficient, a new equation which points out the inherent relationship of the fan blade setting angle, fan rotating speed and gas flow rate in wind tunnel circuit is derived according to the two-dimensional flow theory of the axial fan rotor blades and the aerodynamic characteristics of the low speed wind tunnel. So a new method for setting angle adjustment of fan rotor blade to satisfy the fan performance at off-design point by getting the test results of fan operation parameters but without the fan total pressure rise in the low speed wind tunnel is developed. Flowing the new method, the setting angle adjusting value of fan rotor blade was provided only with the fan rotating speed and flow velocity in the test section of a low speed wind tunnel directly before the fan setting angle altered, the adjusting target was achieved by the new blade setting angle successfully and the time and cost of the wind tunnel commissioning test were saved. The test results show that, after increasing the fan rotor blade setting angle by 4.5 degrees, when the flow velocity in the wind tunnel test section reaches 60 m/s, the fan rotating speed is 570 r/min, the deviation from the predicted fan rotating speed value of 575 r/min is 0.9%. For the same test section flow velocity, the predicted value of the fan rotating speed is in a good agreement with the real value, it proves that this method is reliable and accurate in practical application.

scholarly journals Influence of Chord Lengths of Splitter Blades on Performance of Small Axial Flow Fan

2015 ◽  
Vol 9 (1) ◽  
pp. 361-370
Author(s):  
Guoqi Li ◽  
Lifu Zhu ◽  
Yongjun Hu ◽  
Yingzi Jin ◽  
Toshiaki Setoguchi ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Axial Flow ◽  
Internal Flow ◽  
Leading Edge ◽  
Chord Length ◽  
Aerodynamic Noise ◽  
Axial Fan ◽  
Axial Flow Fan ◽  
Suction Surface ◽  
Small Axial Flow Fan

On the basis of small axial fan with five blades, 6 types of small axial flow fans with different chord lengths splitter blades were designed. Numerical simulation of 6 fan models with splitter blades and prototype fan were done by using Fluent. Based on the obtained simulation results, internal flow characteristics and aerodynamic noise were analyzed and compared. It indicates that: splitter blades with suitable chord length have improved significantly on internal flow characteristics, which inhibits backflow from pressure surface to the suction surface at blade tip and leading edge and restrains flow separation. The 6 model fans are better than prototype fan on aerodynamic noise improvement, but too long or too short chord lengths are both disadvantage to improve aerodynamic noise. The results reveal that 2/6, 3/6 and 4/6 chord length model have relatively better acoustic characteristics and internal flow characteristics. The research program will offer a reference for structural improvements and noise reduction on small axial flow fan.

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