Calamar-E

Cavity Actuated Low-Speed Actively Maneuverable Aquatic Rover Experiment

	Project
	Calamar-E is a University of Colorado Aerospace Engineering Senior Design project for the 2005-2006 academic year. Aerospace Engineering Senior Design is the culmination of the undergraduate aerospace curriculum that allows teams of students to design and manufacture a project of their own creation over the course of the academic year. Funding is provided by the Aerospace Engineering department as well as any external grants or sponsorships teams can obtain. Students are guided and advised by a Project Advisory Board (PAB) as well as any other faculty or external professionals that are willing to help. The result of senior design is that students receive an experience assumed close to what they will in industry so as to be prepared to enter their careers having some knowledge of how to work on a project in a team that is subject to time and financial constraints and external customer requirements. This page is a synopsis of the project in general. For a complete look, check out our Preliminary Design Review presentation (requires MS Powerpoint or OpenOffice) in the file archive

	Mission
	The purpose of this project is to conceptualize, design, fabricate, test, and verify the performance of synthetic vortex-generating actuators when implemented in a highly maneuverable, low-speed submersible vehicle. This new thrust-generating technology has yet to be successfully optimized for implementation on an operational vehicle. Calamar-E aims to provide verification that synthetic vortex generators can be a viable means for providing thrust for submersible vehicles that require high, low-speed maneuverability while maintaining a low-drag profile that allows them to remain independent from a carrier ship. This project is primarily concerned with low-speed accurate maneuverability and not with low-drag, high speed. However the proposed vehicle will be designed with future optimizations for rapid transport movement in mind.

	Drivers
	Thus far in submersible vehicles, there are two design configurations: low-drag, high speed "torpedo" configuration and the low speed, so-called "box" configuration.
	The torpedo configuration is designed for high-speed transport. These vehicles use control surfaces to make minor course adjustments during traversal between two points, much like any transport aircraft does. They are optimized for this type of motion since they have low drag in water and require only their missle-like control surfaces to maneuver. However, they require significant freestream fluid velocity to maneuver at all since control surfaces do not work well unless this condition is met, much like aircraft, again. These vehicles can be launched from a remote carrier vessel and can remain independent until they reach their target destination. They cannot be used for applications that require accurate attitude control and thus are relegated to use in weapons and science vehicles that have missions not requiring accurate positioning and maneuvering.
	The "Box" configuration is the functional inverse of the torpedo configuration. These types of vehicles require a carrier vessel close by at all times and are often even teathered. They have the ability to maneuver accurately by making precise attitude adjustments, typically by utilizing low-speed fan-like thrusters. They are incapable of high-speed traversal due to their poor drag profile and inadequate forward thrust capabilities. Box vehicles are often used for deep-sea exploration since they possess the ability to move in and around wreckages and control their attitude precisely enough to take certain data or photographs and video. Unfortunately, the requirement of a carrier mothership limits them to operating in regions that the ship can. This excludes quite a number of regions, the most obvious of which are the polar regions where ice prevents carrier vessels from entering. A box vehicle cannot explore beneath polar ice since it cannot receive support from its carrier ship.
	The Calamar-E vehicle aims to utilize a new thrusting method that will allow it to be capable of operating as both a high-speed, low drag transport vehicle as well as an accurately maneuvering, low-speed research and exploration vehicle. Such a vehicle would be adept at performing scientific missions in the arctic polar region where ocean thermal balance is of interest but where no ships can go. Proposed mission profiles have an autonomous underwater vehicle (AUV) that moves quickly between station buoys (as shown in the figure above) where it would slow down, carefully dock and upload data to be transmitted to a satellite, recharge and head to the next objective or buoy.
	Calamar-E is a hydridization of current AUV configurations that utilizes new cavity-actuation technology to meet its movement requirements.

	Technology
	A new thrust mechanism has been the subject of research here at the University of Colorado as well as at CalTech and a few other universities. The Calamar-E project's customer, Dr. Kamran Mohseni, is the leading researcher in this material and is assisting the project in developing vehicle-ready actuation devices that will validate theoretical research that has been done at this point. This vehicle will utilize synthetic vortex generators as thrusting devices. This concept is based off biomimicry, specifically, taken from nature's own jet-thrusting cephalopod: the squid.
	Squids generate thrust by intaking water into a mantle cavity, contracting it, and forcing it out the other end, thus creating a force in the opposite direction. By ejecting this jet of water (modeled as a slug of water), simple momentum balance shows that thrust is generated. However, this action also generates near-perfect ring vortices if accomplished cleanly. When the water jet being ejected from an orifice interacts with effectively stangant ambient fluid, it injects its momentum into the formation of these vortices, thereby producing a thrust in the opposite direction of the vortices' travel.
	Research by Mohseni et. al. thus far has shown that a device can be produced to create this effect. Such a device is referred to as a synthetic jet actuator or vortex generator. However, these devices are in their infancy and have yet to be proven to be a viable thrust option. Calamar-E will design actuators that utilize this fluid effect to generate thrust for an underwater vehicle.
	Synthetic jet actuators generally have some sort of cavity from which water is ejected and some mechanism that drives a plunger that forces water out of an orifice (ideally, a specially designed nozzle) and sucks it back in. These actions oscillate to create a pulsatory thrust system that continuously generates ring vortices and an overall mean thrust. There are numerous of design options for all the components of the entire device so no configuration can be seen as the ultimate best at this stage in development. An example of a functional actuator is this large, test model that has been in operation in the Microfluidics Laboratory at the University of Colorado (It utilizes a type of cam-follower design for its driver mechanism). Under nominal operating conditions it can produce as much as 0.5N of thrust at an oscillation frequency range of 30-40Hz. This actuator is merely a test-bed and is far too large and non-specific to be implemented in a vehicular system. Calamar-E will design new actuators that will be vehicle grade and capable of demonstrating the usefulness of this technology for aquatic thrust.