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Experimental Study of Passive Control Method of Pipeline Cavity Flow

HUANG You;OUYANG Hua;WU Ya-dong;TIAN Jie;DU Zhao-hui

2012, 32 (4): 46-50. DOI: 10.3969/j.issn.1006-1355.2012.04.0011

Abstract （1635）

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Experiments were carried out in order to investigate the rectangular cavity flow of length-to-depth ratio of 5:1 using time-resolved particle image velocimetry (TR-PIV) technique. Three different passive control methods, including cylinder, sawtooth and rectangle body, were studied experimentally, having the same upstream velocity, i.e. 34 m/s. The experimental results show that the cylinder control method can increase shear layer thickness and effectively reduce the shear layer speed pulse and vorticity. Rectangle and sawtooth control methods will obviously raise shear layer to mainstream area, leading to no frontal impinging between the shear layer and the trailing edge of the cavity edge.

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Effect of Penetration on Aerodynamic Acoustic Characteristics of Chevron Nozzle

ZHU Xi-jia;OU-YANG Hua;TIAN Jie;DU Zhao-hui

2011, 31 (5): 113-116. DOI: 10.3969/j.issn.1006-1355-2011.05.026

Abstract （2025）

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Using TR-PIV technique and far-field measurement method, the aerodynamic acoustic characteristics of chevron nozzles with different penetrations have been studied at the Mach number Ma=0.12. Flow field results show that the chevron nozzles can reduce the potential core length and increase the mixing of the air flows in the core with the environment. With the penetration being higher, this tendency is increased. It is found that the chevron nozzles with high penetration can reduce low frequency noise, but increases high frequency noise; while the chevron nozzles with low penetration can reduce the global sound pressure level of the noise effectively. At aft angle of 150°, the chevron nozzle with low penetration can bring noise suppression by 1.3 dB. This work is of practical significance for jet noise control of factories.

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《Experimental Study on Acoustic Characteristics of the Muffler with Inserted Pipes》

DU Jiang;OUYANG Hua;DU Zhao-hui

2010, 30 (4): 104-109. DOI: 10.3969/j.issn.1006-1355.2010.04.028

Abstract （2176）

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The experimental study was carried out on both the internal and external acoustic characteristics of the muffler with inserted pipes. The lengthtodiameter ratio L/D of the pipes is 3.98 and the air velocity in the pipes is from 10m/s to 100m/s. The effects of air velocity and structure parameters on the acoustic characteristics of the muffler were studied. The acoustic characteristic mechanism of the muffler with inserted pipes was analyzed according to the air vortex mode in the cavity of the muffler and the acoustic modes of both cavity in muffler and tail pipe. It is found that both the internal and external acoustic characteristics of the muffler are influenced greatly by the air velocity. The acoustic characteristics of insertedpipe muffler are closely related to the acoustic mode of cavity in muffler and the acoustic mode of tail pipe, but they are essentially independent of the vortex mode of the air regeneration noise in the muffler.