College of Graduate Studies: Theses & Dissertations

Term of Award

Spring 2026

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Marcel Ilie

Committee Member 1

Mosfequr Rahman

Committee Member 2

Shaowen Xu

Abstract

This thesis investigates the effect of internal chamber geometry on the performance of a piezoelectric oscillating water column (OWC) wave energy harvester. Four acrylic chamber configurations with internal top-surface angles of 0°, 30°, 45°, and 60° were tested under 32 controlled conditions combining synchronous (SYN) and asynchronous (ASC) forcing at input voltages of 4, 6, 8, and 10 V. A 35 mm piezoelectric disc mounted at the chamber roof served as the power take-off element and, subject to the RC-limit caveat disclosed in Section 3.2.1, as a first-order dynamic analogue of the chamber pressure for phase-based compressibility analysis. All test cases operated within the compressible regime, with Ω ranging from 0.228 to 0.971. The results show a clear advantage for synchronous forcing, which produced mean outputs of 122.3 mV and 6.93 nW, compared with 99.1 mV and 4.54 nW under asynchronous forcing. Among the four geometries, the 45° chamber delivered the strongest overall performance, with the highest mean Vᵣₘₛ of 118.0 mV and the highest mean estimated power of 6.55 nW. The best individual case was recorded for the 45°/SYN/10 V condition, which reached 155.0 mV and 10.92 nW. Overall, the findings show that electrical output is shaped by the combined effects of geometry, forcing mode, and wave power, with the 45° chamber and synchronous forcing giving the most favourable performance within the scope of this study. The mode effect is statistically significant at α = 0.05 (F = 19.6, p < 0.001 for Vᵣₘₛ), while the geometry main effect has a medium practical effect size (Cohen's d = 0.56–0.65; η² ≈ 0.07) but does not reach α = 0.05 at the present replication of n = 8 per geometry — a power-limited outcome that the study addresses in its future-work recommendations.

Research Data and Supplementary Material

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