Abstract:
Enhancement in the stealth capabilities of conventional submersible during surfacing or snorkeling require a reduction in the acoustic and thermal/IR signatures generated by the diesel engine exhaust. Exhaust noise has long been recognized as the primary noise source for diesel engines and is controlled through the use of silencers. The optimum design of a silencer requires prediction of its acoustic and aerodynamic performance. The aim of present study is to simulate the acoustic and aerodynamic performance of submersible reactive silencers and to minimize the Thermal/IR signatures of engine exhaust. Cooling of exhaust gas decreases the temperature of tail pipe and a shift in the wavelength, thus masking the associated IR signatures, which can be achieved by the use of dry type cooling silencer. Four reactive silencers analyzed in detail having same length and diameter but different configurations are expansion chamber with offset extended inlet/outlet, expansion chamber with offset extended perforated inlet/outlet, double expansion chamber reactive silencer with double interconnecting tubes and reversing flow silencer. Transmission loss (TL), chosen as acoustic performance criteria, is predicted by FEM/BEM based computational acoustics program SYSNOISE, whereas pressure drop and temperature drop simulations are carried out by using commercial CFD software FLUENT. Numerical simulation results show that double chamber reactive silencers with double inter-connecting tubes have higher pressure drop and provide higher acoustic attenuation as compared to other silencers at most frequencies after its first pass frequency. Using guiding annulus, the pressure drop may be decreased effectively, with negligible effect on acoustic attenuation perform-ance. Temperature drop numerical simulation results of cooling silencers show that increasing the exhaust inlet velocity adversely affect the cooling process, resulting in a lower overall temperature drop.
Page(s):
224-235
DOI:
DOI not available
Published:
Journal: Proceedings 6th International Bhurban Conference on Applied Sciences and Technology , Volume: 1, Issue: 0, Year: 2009