Background

Controlled application of the Coanda effect to the duct of a marine Kort-nozzle propulsor can yield large lateral forces, comparable to or larger than those produced by a rudder.  The ability of a C3M system to vector large amounts of thrust rivals that of a Z-drive propulsor.  The C3M system, however, exposes no vulnerable parts to damage and has no additional bearings, seals or gears to maintain.  Further a C3M system can be locally manufactured and installed in new-building craft or retrofitted at a lower cost than foreign built Z-drives.

Objectives

Demonstrate and measure the C3M enhanced forces on realistic, operating Kort-nozzle propulsors and associated rudders.

Determine the limits imposed by cavitation and ventilation, and devise ways to extend them.

Examine the performance consequences of various system protective arrangements.

Application Potential and Uses

With the U. S. Navy's support via  various agencies, demonstrations toward augmenting the directional control of submarines operating at low speeds were carried out using a ring-duct model in a wind tunnel.  These demonstrations have successfully shown that C3M is effective.

In addition to Naval applications regarding submarine control, commercial applications of this technology are to be most promising.  Foremost is an application to the heavily loaded propulsors of towboats engaged in riverine barge traffic.  The annual tonnage moved in this trade far exceeds that of the U. S. blue-water commercial fleet - and all of it is American made and operated.  The economy and safety - both environmental and material - of the vessels in this trade will be significantly enhanced by the successful adoption of the prospective maneuvering system.

Other applications include tugboats, fireboats, and fishing craft - wherever maneuvering power is desired in heavily loaded working craft.

Development Partners/Principal Industry Collaborators

Bird-Johnson Company, a major designer and manufacturer of large workboat propulsors and thrusters, as well as the principal supplier of controllable/reversible pitch propellers to the U. S. Navy, is our principal industry collaborator.  A representative of the U. S. Army Corps of Engineers, Philadelphia Design Center, also acts as an industry collaborator.  The COE is responsible for the safe and efficient use of our waterways.

Project Status

Six months into our two-year program, we have completed the design of our model-scale equipment and protocols for testing in the University of New Orleans towing tank.  Early stage testing is now underway, as we await the completion of Coanda system-equipped propulsor models being manufactured by expert machinists.

Future Plans

As models become available, we intend to rapidly expand the experimental and analytical performance data base.  We shall employ transient operating conditions in the towing tank with PC-based data acquisition and analysis to rapidly explore the ranges of a number of important parameters, such as the Coanda blowing-slot flow rate, propulsor loading, and vehicle turning rate.

As the "envelope" of C3M system performance takes shape, we shall disseminate the information to operators and shipyards to enlist their backing for commercialization of the technology.  To these ends, we shall soon begin a preliminary design of a full-scale C3M system for retrofit to an existing commercial or Government vessel for test and evaluation.

Neal A. Brown, PhD
(504) 280-7183
nabna@uno.edu

GCRMTC TECHNICAL BRIEFS are published periodically by the Gulf Coast Region Maritime Technology Center, a U.S. Navy Center of Excellence in Advanced Marine Technology based at the University of New Orleans.  GCRMTC's Mission is to "enhance international competitiveness in the U.S. shipbuilding industry through sponsored research."   For additional information, contact:  GCRMTC, University of New Orleans, New Orleans, LA 70148, Tel: (504) 280-3871, Fax: (504) 280-3898, E-mail: jtsen@uno.edu

The contents of this publication reflect the views of the MERIC staff and are based on information obtained from the literature.  The contents do not necessarily reflect the official views or the policies of MERIC or the Gulf Coast Maritime Technology Center.  This publication does not constitute a standard, specification, or regulation.  MERIC does not endorse products, equipment or manufacturers.  Trademarks or manufacturer's names appear herein only because they are considered essential to the object of this publication.