Title Noise suppression of a dipole source by tensioned membranewith side - branch cavities
نویسندگان
چکیده
Reducing the ducted-fan noise at the low frequency range remains a big technical challenge. This study presents a passive approach to directly suppress the dipole sound radiation from an axial-flow fan housed by a tensioned membrane with cavity backing. The method aims at achieving control of low frequency noise with an appreciable bandwidth. The use of the membrane not only eliminates the aerodynamic loss of flow, but also provides flexibility in controlling the range of the stopband with high insertion loss by varying its tension and mass. A three-dimensional model is presented which allows the performance of the proposed device to be explored analytically. With the proper design, this device can achieve a noise reduction of 5 dB higher than the empty expansion cavity recently proposed by Huang et al. Through the detailed modal analysis, even in vacuo modes of the membrane vibration are found to play an important role in the suppression of sound radiation from the dipole source. Experimental validation is conducted with a loudspeaker as the dipole source and good agreement between the predicted and measured insertion loss is achieved.
منابع مشابه
Title Noise Suppression of a Dipole Source by Tensioned Membrane with Side-branch Cavities Rights This Work Is Licensed under a Creative Commons Attribution- Noncommercial-noderivatives 4.0 International License. Noise Suppression of a Dipole Source by Tensioned Membrane with Side-branch Cavities
Reducing the ducted-fan noise at the low frequency range remains a big technical challenge. This study presents a passive approach to directly suppress the dipole sound radiation from an axial-flow fan housed by a tensioned membrane with cavity backing. The method aims at achieving control of low frequency noise with an appreciable bandwidth. The use of the membrane not only eliminates the aero...
متن کاملNoise suppression of a dipole source by tensioned membrane with side-branch cavities.
Reducing the ducted-fan noise at the low frequency range remains a big technical challenge. This study presents a passive approach to directly suppress the dipole sound radiation from an axial-flow fan housed by a tensioned membrane with cavity backing. The method aims at achieving control of low frequency noise with an appreciable bandwidth. The use of the membrane not only eliminates the aero...
متن کاملDamage Detection in Post-tensioned Slab Using 2D Wavelet Transforms
Earthquake force, loading more than structural capacity, cracking, material fatigue and the other unpredicted events were undeniable in the structure life cycle in order that environmental conditions of the structure would be changed and treats health. Damage of structures such as crack, corrosion of the post tension cables from inappropriate grouting of the post tension structures and etc. can...
متن کاملProgress in the search for the optimum light source : squeezing experiments with a frequency doubler
AbstraeL Real lasers show inuinsic noise well above the standard quantum noise limit. We review the propenies of lasers and of techniques to suppress this noise. Experimental results of elenroqxic feedback techniques and of squeezing in a sewnd harmonic genenuor are presented. pinally we show that the optimum light s o w e could well be a cascade of different cavities, each one performing a spe...
متن کامل