The noise characteristics of the jets exhausted from nozzles with diameters of 10 mm and 20 mm are experimentally studied at the gas flow rate of 30-150 m3/h. The effects of nozzle size on the underwater exhaust noise in different frequency bands are analyzed. Moreover, the noise reduction effect of a multi-nozzle exhaust scheme is investigated. The results show that the noise with frequencies of 10-100 Hz would decrease with nozzle size decreasing. The noise with frequencies of 100-1 000 Hz are very sensitive to gas velocity, and would increase with gas velocity increasing. Hence under certain gas flow rate conditions, reducing the nozzle size would increase the noise with frequencies of 100-1 000 Hz. For the reason, replacing a single large-size nozzle with several small-size nozzles would reduce the exhaust noise in the case of the total cross-sectional area unchanged.
XU Weiwei, WU Dazhuan, WANG Leqin, et al. Ana-lysis on characteristics of new muffler for marine pipelines [J]. Journal of drainage and irrigation machinery engineering, 2013, 31(2): 142-145.(in Chinese)
ZHANG Wenping, MA Qiang, ZHANG Zhihua, et al. Study on the influencing factors of the underwater exhaust noise of diesel engine and the ways of noise reduction. [J]. Journal of Harbin Shipbuilding Engineering Institute, 1991, 12(4): 406-414.(in Chinese)
CHEN L, MANASSEH R, NIKOLOVKSA A, et al. Noise generation by an underwater gas jet[C]//Proceedings of the 8th Western Pacific Acoustics Confe-rence, 2003:1-4.
MANASSEH R, RIBOUX G, RISSO F. Sound generation on bubble coalescence following detachment[J]. International journal of multiphase flow, 2008, 34(10): 938-949.
GAVIGAN J J, WATSON E E, KING W F. Noise ge-neration by gas jets in a turbulent wake[J]. The journal of the acoustical society of America, 1974, 56(4): 1094-1099.
DEANE G B, STOKES M D. The acoustic excitation of air bubbles fragmenting in sheared flow[J]. The journal of the acoustical society of America, 2008, 124(6): 3450-3463.
LINCK M, GUPTA A K, YU K. Submerged combustion and two-phase exhaust jet instabilities[J]. Journal of propulsion and power, 2009, 25(2): 522-532.