Mid-March
2007
Table
of Contents:
New England Section |
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Greek Section |
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Mid-March
2007
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New
England Section February 8, 2007 On February 8, 2007, the The New England Section hosted their annual student papers night met on the campus of the Massachusetts Institute of Technology (MIT) for our annual student papers’ night. We had Student entries included from students representing MIT, U.S. Coast Guard Academy, Maine Maritime Academy, and the University of New Hampshire. Written copies of all papers were available to members and guests as they signed in. Mr. Greg Beers, Papers Chair, kept the evening moving. Each student, or team of students, was given 10 minutes to present their paper, followed by a five minute question and answer period. Certificates of Appreciation were presented to all contributors at the end of the evening.
Greek
Section February 15, 2007 On February 15th, 2007, the Greek Section had its fifth technical meeting for the 2006-2007 season. Mr. Johannsen, Director of Propellers & Cavitation Department in Hamburg Ship Model Basin, gave a comprehensive presentation on the problem of rudder cavitation in high performance, highly-powered ships. The background on cavitation, the vaporization of water in low-pressure regions of the flow, was analyzed and shown to be an unavoidable but critical phenomenon at the propellers of seagoing ships. The challenges involved in high-power density propeller disks were presented, and sophisticated investigations were exemplified, as a matter of course to avoid problems resulting from unfavorable propeller cavitation behavior. With the recent trend of ever-larger container vessels and higher speed passenger ferries, cavitation has been known to become a problem for the rudders as well. Johannsen provided the theoretical background for such cavitation behavior and categorized the known occurrences to their differing origins: gap, rudder sheet and rudder tip-vortex cavitation to name a few. Instances of severe damages were shown from full scale ships and sophisticated model testing procedures along with numerical methodologies were presented as means to provide solutions to existing ships and thus avoid such problems in future designs. Practical advise for optimal rudder choice as well as design guidelines were given, such as the introduction of spoilers, baffle plates, gap avoidance, asymmetric rudder design, etc.
Following the presentation, Kristen Navigation hosted a reception. The event was attended by over thirty members of SNAME and visitors.
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