scholarly journals Attenuation of Cross-Flow Fan Noise Using Porous Stabilizers

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
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.

Noise Controlling Using Porous Stabilizers in a Cross-Flow Fan

2012 ◽  
Author(s):  
Huanxin Lai ◽  
Hongbo Zhang ◽  
Jin Yao ◽  
Gailan Xing
Keyword(s):  
Pressure Fluctuations ◽  
Cross Flow ◽  
Internal Flow ◽  
Considerable Effect ◽  
Performance Curve ◽  
Fan Noise ◽  
Radiated Noise ◽  
Instantaneous Pressure ◽  
The Cross ◽  
Cross Flow Fan

Experimental measurements and simulations are carried out to study the performances and the unsteady internal flow fields of a cross-flow fan (CFF), which uses a kind of porous stabilizers proposed by the authors in an attempt to control the noise. The performance curve and sound radiation of the fan as well as instantaneous pressure fluctuations in the flowfield are measured and analysed. Transient calculations of the flowfield are carried out to study the vortical flows inside the fan as well as in the porpous stabilizers. The results show that the porous stabilizers have not produced considerable effect on the cross-flow fan’s performance curve, but the amplitude of the pressure fluctuation and the level of radiated noise are affected. This qualitative study indicates the cross-flow fan noise may be controlled by using the porous stabilizers if the porosity is properly selected.

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

2012 ◽  
Vol 134 (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.

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

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.

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

2010 ◽  
Author(s):  
You Li ◽  
Hua Ouyang ◽  
Jie Tian ◽  
Zhiming Zheng ◽  
Zhaohui Du
Keyword(s):  
Relative Velocity ◽  
Numerical Solutions ◽  
Cross Flow ◽  
Internal Flow ◽  
Flow Patterns ◽  
Far Field ◽  
Numerical Studies ◽  
Aerodynamic Performances ◽  
Field Noise ◽  
Cross Flow Fan

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.

Experimental and Computational Investigation of Cross-Flow Fan Propulsion for Lightweight VTOL Aircraft

2004 ◽  
Author(s):  
Garth V. Hobson ◽  
W. T. Cheng ◽  
M. Scot Seaton ◽  
Anthony Gannon ◽  
Max F. Platzer
Keyword(s):  
Cross Flow ◽  
Performance Data ◽  
Power Ratio ◽  
Performance Measurements ◽  
Promising Alternative ◽  
Rotary Engine ◽  
Speed Range ◽  
The Cross ◽  
Cross Flow Fan ◽  
Vtol Aircraft

Cross-flow fan propulsion has not been seriously considered for aircraft use since an Vought Systems Division (VSD) study for the U.S. Navy in 1975. A recent conceptual design study of light-weight, single seat VTOL aircraft suggest that rotary-engine powered cross-flow fans may constitute a promising alternative to the conventional lift-fan vertical thrust augmentation systems for VTOL aircraft. The cross-flow fan performance data obtained by VSD supported the hypothesis that they could be improved to the point where their thrust augmentation could be used in a VTOL aircraft. In this paper we report results of a NASA Glenn supported experimental and computational cross-flow fan investigation which is currently in progress and we provide an assessment of the potential suitability of crossflow fans for VTOL aircraft propulsion. The tests are carried out in the Turbopropulsion Laboratory of the Naval Postgraduate School, using an existing Turbine Test Rig as a power source to drive the cross-flow fan. A 0.305 m (12-inch) diameter, 38.1 mm (1.5-inch) span cross-flow fan test article was constructed to duplicate as closely as possible the VSD fan so that baseline comparison performance data could be obtained. Performance measurements were taken over a speed range of 1,000 to 7,000 RPM and results comparable to those measured by Vought Systems Division were obtained. At 3,000 RPM a 2:1 thrust-to-power ratio was measured which dropped to one as the speed was increased to 6,000 RPM. Performance maps were experimentally determined for the baseline configuration as well as one with both cavities blanked off, for the speed range from 2,000 to 6,000 rpm. Using Flo++, a commercial PC-based computational fluid dynamics software package by Softflo, 2-D numerical simulations of the flow through the cross-flow fan were also obtained. Based on the performance measurements it was concluded that the optimum speed range for this rotor configuration was in the 3,000 to 5,000 rpm range. The lower speed producing the best thrust-to-power ratio and the upper speed range producing the highest efficiency over sizeable throttling range.

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

2010 ◽  
Vol 71 (12) ◽  
pp. 1142-1155 ◽  
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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