Date Available

7-29-2024

Year of Publication

2024

Degree Name

Master of Engineering (ME)

Document Type

Master's Thesis

College

Engineering

Department/School/Program

Mechanical Engineering

First Advisor

Dr. David Herrin

Abstract

Mufflers and silencers are commonly used to control noise from sources such as internal combustion engines and heating, ventilating, and air conditioning (HVAC) systems. In these applications, flow interacts with muffler components generating aeroacoustic noise sources. In order to measure these sources in a lab setting, specialized flow rigs are designed to isolate aeroacoustic noise sources. Flow sometimes compromises muffler performance. However, muffler performance is sometimes improved because flow can increase the attenuation of some muffler elements such as perforates. To better understand the complicated impact of flow, the University of Kentucky developed a muffler test rig to measure insertion loss and noise reduction with flow included. Additionally, the rig can be used to isolate and quantify the aeroacoustic sources inside of a muffler or at the termination. In this research, the test rig is first validated by measuring the aeroacoustic sources for a subsonic jet at the outlet of a straight pipe. Data is compared with theory to verify that the measured aeroacoustic sources match what is anticipated from well understood acoustic source power laws. The test rig is then used to measure the whistle tones generated by a perforated concentric tube resonator. The effect of hole diameter and porosity is evaluated. Finally, a subsonic jet is simulated using computational fluid dynamics and acoustic finite element analysis. The measured sound power is compared with the aeroacoustic simulation and correlation is excellent.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.336

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