Thesis
Demonstration of acoustic instability in resonators with heat addition and mean flow
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/102862
Abstract
Thermoacoustic instabilities can arise in systems where unsteady heat release is favorably coupled with acoustic pressure oscillations. A modified Rijke tube with segments having different sections is found to have lower threshold levels of heat addition rate needed for exciting the fundamental acoustic mode of the tube. Experiments indicate that about 115 W of heating power is required to produce sound in the 90 cm long segmented tube, while over 230 W is needed in 60 cm long and 90 cm long tubes with constant-area cross sections. One of the causes for lowering the threshold of heat addition rate is due to a significant reduction of the resonator natural frequency. The presented results suggest an importance of including the system geometry details into analysis of practical devices prone to thermoacoustic instabilities. v Two types of acoustic energy harvesters are also tested and demonstrated in this study. Tonal sound is excited by heat addition or vortex shedding/impinging in the presence of mean flow in the resonator. The sound generated within the resonator is partially converted into electrical energy by using a piezoelectric disk with a brass back plate. One of the systems, a thermoacoustic engine, generated a maximum electric power of 0.446 mW at a resistance of 14.8 kΩ. The baffled tube with mean flow produced more than 0.5mW of electric power at a resistance of 10 kΩ and mean velocity of 2.6 m/s. Optimization of the system geometry and piezoelement are required in order to increase the power output.
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Details
- Title
- Demonstration of acoustic instability in resonators with heat addition and mean flow
- Creators
- Rafael Hernandez
- Contributors
- Konstantin I. Matveev (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525401401842
- Language
- English
- Resource Type
- Thesis