Internal Flow and Noise Investigations About the Cross-Flow Fan With Different Blade Angles

The experimental and numerical studies have been carried out to investigate the flow and the noise characters of the three impellers with different blade angles in a cross-flow fan (CFF). Firstly, the aerodynamic performances of the fan with these impellers are obtained experimentally and the averaged flow patterns inside the impellers are measured by the three-hole probe. Secondly, the far-field noise generated by CFF with different impellers has been measured in a semi-anechoic chamber under different throttling conditions. Thirdly, the two-dimensional unsteady CFD simulations have been performed by commercial software. The internal flow patterns influenced by the different blade angles have been summarized through the computational results. The accuracy of the calculations is validated by the corresponding experimental ones. The detail analysis has been carried out on the unsteady vortex flow properties of the three impellers, which is considered to be the main factor that influences the aerodynamic and aeroacoustic performance of the CFF. Finally, the relative far field noise generated by different impellers are evaluated by an empirical formula based on the assumption that the total sound pressure levels are proportional to the sixth power law of the relative velocity on the outer and inner circumferences of the impeller. The circumferential distributions of relative velocity are provided from the numerical solutions. The varying trends of predicted results agree well with the actual relative noise of the CFF with three different impellers.

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Internal Flow and Noise Investigations About the Cross-Flow Fan With Different Blade Angles

Journal of Turbomachinery ◽

10.1115/1.4004485 ◽

2012 ◽

Vol 134 (5) ◽

Cited By ~ 5

Author(s):

Hua Ouyang ◽

Jie Tian ◽

You Li ◽

Zhiming Zheng ◽

Zhaohui Du

Keyword(s):

Relative Velocity ◽

Numerical Solutions ◽

Cross Flow ◽

Internal Flow ◽

Flow Patterns ◽

Far Field ◽

Noise Characteristics ◽

Aerodynamic Performances ◽

Field Noise ◽

Cross Flow Fan

The experimental and numerical studies have been carried out to investigate the flow and the noise characteristics of the three impellers with different blade angles in a cross-flow fan (CFF). First, the aerodynamic performances of the fan with these impellers are obtained experimentally, and the averaged flow patterns inside the impellers are measured by the three-hole probe. Second, the far-field noise generated by CFF with different impellers has been measured in a semianechoic chamber under different throttling conditions. Third, the two-dimensional unsteady CFD simulations have been performed by commercial software. The internal flow patterns influenced by the different blade angles have been summarized through the computational results. The accuracy of the calculations is validated by the corresponding experimental ones. The detail analysis has been carried out on the unsteady vortex flow properties of the three impellers, which is considered to be the main factor that influences the aerodynamic and aeroacoustic performance of the CFF. Finally, the relative far field noise generated by different impellers are evaluated by an empirical formula based on the assumption that the total sound pressure levels are proportional to the sixth power law of the relative velocity on the outer and inner circumferences of the impeller. The circumferential distributions of relative velocity are provided from the numerical solutions. The varying trends of predicted results agree well with the actual relative noise of the CFF with three different impellers.

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Attenuation of Cross-Flow Fan Noise Using Porous Stabilizers

International Journal of Rotating Machinery ◽

10.1155/2011/528927 ◽

2011 ◽

Vol 2011 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Huanxin Lai ◽

Meng Wang ◽

Chuye Yun ◽

Jin Yao

Keyword(s):

Cross Flow ◽

Sound Radiation ◽

Internal Flow ◽

Considerable Effect ◽

Front Wall ◽

Performance Curve ◽

Fan Noise ◽

Aerodynamic Performances ◽

The Cross ◽

Cross Flow Fan

This paper presents a qualitative analysis of controlling the cross-flow fan noise by using porous stabilizers. The stabilizer was originally a folded plate. It is changed into a porous structure which has a plenum chamber and vent holes on the front wall. In order to investigate the influences of using the porous stabilizers, experiments are carried out to measure the cross-flow fan aerodynamic performances and sound radiation. Meanwhile, the internal flow field of the fan is numerically simulated. The results show that the porous stabilizers have not produced considerable effect on the cross-flow fan's performance curve, but the noise radiated from the fan is strongly affected. This indicates the feasibility of controlling the cross-flow fan noise by using the porous stabilizers with selected porosity.

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PREDICTION OF NOISE GENERATED BY A ROUND NOZZLE JET FLOW USING COMPUTATIONAL AEROACOUSTICS

Journal of Computational Acoustics ◽

10.1142/s0218396x11004365 ◽

2011 ◽

Vol 19 (03) ◽

pp. 291-316 ◽

Cited By ~ 23

Author(s):

ALI UZUN ◽

M. YOUSUFF HUSSAINI

Keyword(s):

Flow Field ◽

Near Field ◽

Internal Flow ◽

Jet Flow ◽

Computational Aeroacoustics ◽

Far Field ◽

Free Jet ◽

Grid Points ◽

Field Noise ◽

Inflow Conditions

This paper demonstrates an application of computational aeroacoustics to the prediction of noise generated by a round nozzle jet flow. In this study, the nozzle internal flow and the free jet flow outside are computed simultaneously by a high-order accurate, multi-block, large-eddy simulation (LES) code with overset grid capability. To simulate the jet flow field and its radiated noise, we solve the governing equations on approximately 370 million grid points using high-fidelity numerical schemes developed for computational aeroacoustics. Projection of the near-field noise to the far-field is accomplished by coupling the LES data with the Ffowcs Williams–Hawkings method. The main emphasis of these simulations is to compute the jet flow in sufficient detail to accurately capture the physical processes that lead to noise generation. Two separate simulations are performed using turbulent and laminar inflow conditions at the jet nozzle inlet. Simulation results are compared with the corresponding experimental measurements. Results show that nozzle inflow conditions have an influence on the jet flow field and far-field noise.

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Experimental and numerical studies on the discrete noise about the cross-flow fan with block-shifted impellers

Applied Acoustics ◽

10.1016/j.apacoust.2010.07.002 ◽

2010 ◽

Vol 71 (12) ◽

pp. 1142-1155 ◽

Cited By ~ 5

Author(s):

You Li ◽

Hua Ouyang ◽

Jie Tian ◽

Zhaohui Du ◽

Zhiming Zheng

Keyword(s):

Cross Flow ◽

Numerical Studies ◽

The Cross ◽

Cross Flow Fan

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Performance and Internal Flow of Cross-Flow Fan with Inlet Guide Vane

JSME International Journal Series B ◽

10.1299/jsmeb.48.763 ◽

2005 ◽

Vol 48 (4) ◽

pp. 763-769 ◽

Cited By ~ 21

Author(s):

Junichiro FUKUTOMI ◽

Rei NAKAMURA

Keyword(s):

Guide Vane ◽

Cross Flow ◽

Internal Flow ◽

Inlet Guide Vane ◽

Cross Flow Fan

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The Influence of Non-Uniform Impeller on the Cross Flow Fan Noise

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.693.251 ◽

2016 ◽

Vol 693 ◽

pp. 251-256

Author(s):

Zhi Qiang Yang ◽

C.J. Wu

Keyword(s):

Pressure Fluctuations ◽

Flow Characteristics ◽

Cross Flow ◽

Internal Flow ◽

Broadband Noise ◽

Aerodynamic Noise ◽

Air Conditioner ◽

Fan Noise ◽

Power Spectral ◽

Cross Flow Fan

The aerodynamic noise of a cross flow fan with uneven blade spacing in room air-conditioner was simulated by computational aerodynamic acoustics (CAA) method. It is detailed to analyze the vorticity distribution of the flow field and the power spectral density of measured points’ pressure fluctuations, and the results demonstrate the non-uniform impeller used in this paper can significantly improve internal flow characteristics. Thus the broadband noise got reduced.

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Geometric optimization of cross-flow heat exchanger based on dynamic controllability

Thermal Science ◽

10.2298/tsci0803075a ◽

2008 ◽

Vol 12 (3) ◽

pp. 75-84

Author(s):

Sorour Alotaibi ◽

Asad Alebrahim

Keyword(s):

Aspect Ratio ◽

Mass Flow ◽

Numerical Solutions ◽

Cross Flow ◽

Internal Flow ◽

Geometric Optimization ◽

Transient Model ◽

The Face ◽

Mass Flow Rates ◽

Water Mass Flow Rate

The operation of heat exchangers and other thermal equipments in the face of variable loads is usually controlled by manipulating inlet fluid temperatures or mass flow rates, where the controlled variable is usually one of the output temperatures. The aim of this work is to optimize the geometry of a tube with internal flow of water and an external cross-flow of air, based on its controllability characteristics. Controllability is a useful concept both from theoretical and practical perspective since it tells us if a particular output can be controlled by a particular input. This concept can also provide us with information about the easiest operating condition to control a particular output. A transient model of a tube in cross-flow is developed, where an implicit formulation is used for transient numerical solutions. The aspect ratio of the tube is optimized, subject to volume constraints, based on the optimum operation in terms of controllability. The reported optimized aspect ratio, water mass flow rate and controllability are studied for deferent external properties of the tube.

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