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Exploration into the Feasibility of Underwater Synthetic Jet Propulsion


Polsenberg Thomas, AnnMarie (2007) Exploration into the Feasibility of Underwater Synthetic Jet Propulsion. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/72SZ-T823.


This thesis explores the feasibility of using synthetic jet actuators for the propulsion of small underwater vehicles. This work was inspired by the widespread use of pusatile jet propulsion by sea creatures such as squid, salp, and jellyfish. The jets created by these animals utilize vortex rings for thrust production. A method for creating similar vortex ring-based jets is the use of synthetic, or zero net mass flux, jets. These jets, which form a jet structure through the alternating sucking and blowing of fluid through a single orifice, have previously been investigated for the utility in air flow control.

The design, construction, and testing of aquatic synthetic jet prototypes is presented. Force measurement and flow visualization experiments are performed on these jets to gain an understanding of the forces and flow structures produced. The flow visualizations confirm the outflow vortex ring observations reported previously in the literature and present the first images of vortex ring formation inside the synthetic jet chamber. A new phenomenon, that of self-induced coflow upstream of the jet orifice, is discussed. The force measurements present confirmation that a net thrust is produced by the jets and give insight to the relationship between jet forcing parameters (such as frequency) and the resulting thrust. An automated genetic algorithmic approach to optimizing the thrust for a given jet geometry is also presented and tested.

Using the results of these experiments I propose a model for synthetic jet thrust. This model asserts that there are three force producing components to the flow: orifice inflow, orifice outflow, and a self-induced coflow. The contribution of each of these components is derived and compared with experimental results.

Included at the end of this thesis is a preliminary study into possible vehicle architecture for the utilization of synthetic jet thrusters.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:aquatic propulsion; synthetic jets; underwater robotics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Burdick, Joel Wakeman
Thesis Committee:
  • Burdick, Joel Wakeman (chair)
  • Dabiri, John O. (co-chair)
  • Brennen, Christopher E.
  • Antonsson, Erik K.
Defense Date:25 August 2006
Non-Caltech Author Email:apthomas (AT)
Record Number:CaltechETD:etd-09252006-134742
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3761
Deposited By: Imported from ETD-db
Deposited On:28 Sep 2006
Last Modified:23 Mar 2020 22:12

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