Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150306

150306 - Multi-Resonator Acoustic Muffler for Broadband Frequency Attenuation 

This research presents an acoustic device designed to function as an efficient muffler capable of attenuating a wide range of frequencies. The primary aim of this device is to achieve broadband noise reduction, which is crucial in many residential and industrial applications. The proposed device incorporates a series of short expansion chamber rings. Each expansion chamber ring varies in length and is tailored to attenuate specific frequencies based on its resonance. By combining these side-loaded rings onto a host tube, broadband noise reduction is achieved thanks to the cumulative effects of the individual components and their synergistic interactions. The length variation of the rings allows for adjustable sound suppression which can be tuned to meet the requirements of the application. The structure's open-cylinder design enables unobstructed flow through its center, resulting in a much lower impedance to the free movement of fluid compared to many traditional mufflers. Theoretical calculations and numerical simulations are used to validate and optimize the device. Using the impedance translation theorem, the overall reflection, absorption and transmission coefficients of the device can be calculated using a customized MATLAB code. By implementing a geometry generation function to this code, the structure can be parametrically optimized to suppress noise within any given frequency range. This function works by defining an input consisting of a range of possible values for each geometric parameter. The code then uses this to generate all possible geometries within those constraints. These geometries are systematically tested using the impedance translation theorem and given an overall transmission score. The function then presents the geometry with the best score within the target frequency range. Using finite element analysis, numerical simulations are performed to validate the results of the optimized geometry found through theoretical calculations. Using these methods, a design has been optimized that maximizes transmission loss from 800 Hz to 2000 Hz. The cumulative effect of the tuned resonator rings results in a transmission loss of 20 dB to 40 dB within the target frequency range. The implications of this research are significant for the development of advanced acoustic metamaterial solutions. The demonstrated utility of the device in achieving comprehensive noise control makes it a promising candidate for various applications such as automotive exhaust systems, industrial machinery, and naval vessels. The structure’s adjustability allows it to be adapted to different applications and frequency ranges, making it a versatile solution for noise suppression. The research provides a solid foundation for the development of next-generation acoustic metamaterial devices that can meet the growing demand for effective noise control in various settings where unrestricted fluid flow and broadband attenuation are paramount.

Presenting Author: Joshua Lloyd Rowan University

Presenting Author Biography: My name is Joshua Lloyd and I am a Master's student at Rowan University studying mechanical engineering. I am currently researching acoustic metamaterial mufflers as a research fellow of the university.

Authors:

Joshua Lloyd Rowan University
Chen Shen Rowan University