DESIGN & ANALYSIS OF CYLINDRICAL DUCT AND SPIRAL RESONATORS FOR ATTENUATION OF PASSIVE NOISE CONTROL

摘要

In this paper, design of gradual expansion cylindical duct, design of Spiral Resonator was modelled by Pro-ENGINEER 5.0 Wildfire. Four Models of cylindrical duct were prepared such as Model-I, II, III & IV. Model-I is a simple circular duct, Model-II is a spiral resonator in cylindrical duct, Model-III is a single spiral resonator in gradual expansion cylindrical duct of different offset starting from '0' mm, '50' mm, '100' mm, '150'mm, '200'mm, '250' mm and '300' mm, and Model-IV is a double spiral resonator in cylindrical duct of different offset starting from, '0' mm, '50' mm, '100' mm, '150' mm, '200' mm, and '250' mm. Then comparison were made with Model-I with other three models and analyzed by using ANSYS fluent 14.5 Software. Transmission Loss was calculated by the difference between the outgoing power at the outlet 'w_o' and the incoming power at the inlet 'W_i'. Finally it was concluded that the acoustic attenuation performance of Model- III is increases with increase the distance between Spiral Resonator and the inlet of the Gradual Expansion Chamber. In Model - IV, there is visible strong minimization of sound attenuation of two Spiral resonators when placing them one by one. Presented results show that Spiral Resonator can be an effective additional sound attenuation element for ducted systems.