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原文传递 Studies of Submarine Engine Exhaust Silencers and Thermal Infrared Signature Reduction

论文题名：	Studies of Submarine Engine Exhaust Silencers and Thermal Infrared Signature Reduction
关键词：	潜水艇;热红外线;消音器
摘要：	The 3-D numerical methods are used to predict the acoustic attenuationperformance and flow resistance. characteristics of submarine engine exhaustreactive silencers. In addition, simulations of temperature drop of exhaust gas bythe use of dry type cooling silencer and water injection in tail pipe through spray}:ozzle are also performed. In this thesis, the fundamental theory of acoustic finiteelement method and brief introduction to the finite volume method, as well as therelated software SYSNOISE and FLUENT are introduced. The transmission loss ispredicted by finite element method using SYSNOISE, while pressure drop iscalculated by finite volume method using FLUENT. Temperature drop simulationsof both dry type cooling silencers and water injection in tail pipe are carried out byusing heat txansfer module and spray model in discrete phase modeling of FLUENTsoftware. During surfacing and snorkeling,a submarine has to compromise its inherentstealth,as Exhaust Noise of diesel engines and the associated IR/ThermalSignatures of hot exhaust gases increases the vulnerability towards detection bysonars and IR detectors of hostile ASW aircrafls and vessels. Submarine dieselengine exhaust noise is controlled through the use of reactive silencers. Theobjective of the present work has been to simulate the acoustic and aerodynamicperformance of selected submarine reactive silencers and to devise a method tominimize the IR/Thermal signatures of engine exhaust. Cooling of exhaust gaseswill result in a decrease of temperature of tail pipe or exhaust mast and a shift inthe wavelength, thus masking the associated IR signatures. Numerical results of transmission loss of simple expansion chamber with offsetextended inletloutlet and expansion chamber with offset perforated extendedinletloutlet tubes showed that repeating dome behavior characteristics of onedimensional propagation do not extend beyond the first asymmetric (l, 0) mode.Also predicted pressure drop of these two silencers are almost the same. Doublechamber reactive silencers with double inter-connecting tubes have higherpressure drop and provide higher acoustic attenuation than the single chambersilencer at most frequencies after its first pass frequency. Using guiding annulus,the pressure drop may be decreased effectively, with Negligible effect on acousticattenuation performance. The influence of inereasing the value of clearance "Lc"on the acoustic performance of reversing flow silencer is negligible at lowfrequencies and limited at higher frequencies. For reversing flow silencer,pressure drop varies inversely with the clearance space between the shell andguide plates. Temperature drop rn}merical simulation results of cooling silencers show thatincreasing the exhaust inlet velocity adversely affect the cooling process, resultingin a lower overall temperature drop. Temperature drop of exhaust gas passingthrough cooling silencer depends upon the cooling silencer dimensions i.e. largerthe heat transfer surface area, greater will be reduction in the exhaust gastemperarirre. Water injection in the exhaust gas through spray nozzle hasremarkable results and results in a greater reduction in exhaust gas temperature ascompared to dry type cooling silencer.
作者：	Khurram Shehzad
专业：	Marine Engineering
导师：	Ji Zhenlin
授予学位：	硕士
授予学位单位：	哈尔滨工程大学
学位年度：	2006
正文语种：	中文