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

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.

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.

Design and Experiment of Vibrating Screen Millet Cleaning Devise with Double-fan

2021 ◽  
Vol 37 (2) ◽  
pp. 319-331
Author(s):  
Xinping Li ◽  
Gaoyuan Zhao ◽  
Wenzhe Wang ◽  
Yu Huang ◽  
Jiangtao Ji
Keyword(s):  
Field Test ◽  
Loss Rate ◽  
Cross Flow ◽  
Centrifugal Fan ◽  
Rotating Speed ◽  
Vibrating Screen ◽  
Cleaning Performance ◽  
Cleaning Device ◽  
The Cross ◽  
Cross Flow Fan

HighlightsAccording to the physical characteristics of the millet, the double-layer mesh vibrating screen was used as the cleaning screen to prolong the cleaning time of the millet in the cleaning room, prevent the blocking of the vibrating screen, and improve the cleaning performance of the millet cleaning device.As the air flow produced by centrifugal fan was continuously attenuated on the screen surface, the draft chaser cannot completely discharge the chaffs, stalks and other sundries outside the machine. The cross-flow fan designed at the tail of the vibrating screen worked well for increasing the air flow field, improving the cleaning performance.In order to reduce the unthreshed grain-codes in the threshed mixture, a re-threshing device was installed for the millet cleaning device that transported sundries at the end of the screen to the main threshing roller for re-threshing, which improved the cleaning rate and reduced the loss rate effectively.The mathematical model of four factors quadric regression between the rotating speed of centrifugal fan, cross-flow fan, frequency of vibrating screen, width of sundry outlet and the cleaning performance of the device was established, which was meaningful and had high fitting degree. The results of indoor test shown that the cleaning rate was 98.8% and the loss rate was 1.3%.The results of bench test and field test shown that when the size of the upper screen was 12×12 mm, the size of the lower screen was 6×6 mm, the diameter of the suction port of the cross-flow fan was 15 mm, the rotating speed of the centrifugal fan was 1406 r/min, the rotating speed of the cross-flow fan was 713 r/min, the frequency of the vibrating screen was 5.9 Hz, and the width of the sundry outlet was 178 mm, the cleaning rate of the millet cleaning device was 98.75%, and the loss rate was 1.34%.Abstract. The cleaning device is an important part of the millet combine harvester, which directly affects the performance of the whole machine. Aiming at the problems of low cleaning rate and high loss rate in the traditional air-and-screen cleaning device, a vibrating screen millet cleaning device with double-fan was designed. The structure and relevant parameters of the vibrating screen millet cleaning device with double-fan were analyzed and determined. The effects of the rotating speed of centrifugal fan, the rotating speed of cross-flow fan, the vibrating frequency of vibrating screen and the width of the sundry outlet on the millet cleaning rate and the loss rate were studied by single factor test and the orthogonal combination test of four element quadratic rotation. The regression equation between the rotating speed of centrifugal fan, the rotating speed of cross-flow fan, the vibrating frequency of vibrating screen and the width of the sundry outlet and the millet cleaning rate and the loss rate are constructed was used to optimize and obtain the operation parameters of the cleaning device. The indoor test results showed that when the centrifugal fan speed was 1406 r/min, the cross-flow fan speed was 726 r/min, the vibrating screen frequency was 5.9 Hz, and the width of the sundry outlet was 178 mm, the millet cleaning rate was 98.8%, and the loss rate was 1.3%. The result of field test showed that the cleaning rate and loss rate of the vibrating screen millet cleaning device with double-fan were 98.75% and 1.34%, respectively. Keywords: Double-fan, Double-layer mesh vibrating screen, Field test, Millet.

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.

On similitude of the cross flow fan in a split-type air-conditioner

2008 ◽  
Vol 28 (14-15) ◽  
pp. 1853-1864 ◽  
Author(s):  
Yang-Cheng Shih ◽  
Hung-Chi Hou ◽  
Hsucheng Chiang
Keyword(s):  
Cross Flow ◽  
Air Conditioner ◽  
The Cross ◽  
Cross Flow Fan

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.

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