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January 2012 www.sname.org/sname/mt easement on 70 acres of land around the LCC to guarantee that no development poten- tially interfering with the quiet environment required for acoustic testing would ever occur,? says Etter. ?e navy also has guar- anteed access to use of the crane if desired.? The channel uses fresh water from the municipal water supply. When installing or changing test objects, some 20% of the 1.4 million gallons of water must be removed and temporarily stored in a large tank so that the test section can be opened. According to Etter, all parts of the channel that come into contact with water are made of welded 304L stainless steel. e LCC also was designed to conduct acoustic testing, and can be rigged for very silent operation so acoustic sensors can col- lect data. e motor and pump are mounted on a complex isolation system to eliminate vibrations. Furthermore, the lower section of the LCC is actually built inside a concrete trench, which could be flooded, offering additional sound isolation for measuring acoustic signatures of test models. Turning vanes direct the water to make the 90-degree changes of direction. It then ows through a series of more than one mil-lion very small honeycombed cells to reduce turbulence and improve flow uniformity, before entering the test section. e LCC was designed to be able to test both submerged and surface hulls, but until now had never been used to test a platform with a free surface. To test the interaction between SES skirts and the water surface, the LCC was modied using a gate to create a surface within the test section. e experi- ments are being conducted by a team from the University of Michigan, led by Dr. Steven F. Zalek, under the sponsorship of the Oce of Naval Research (ONR).Building data to reduce risk Kit Ryan is Alion Science and Technology?s chief naval architect and was the technical director on the company?s T-Craft design eort that occurred over a three-year period ending May 2010. With more than 40 years of professional experience, Ryan previously served at the Naval Sea Systems Command on a number of ship programs and now works with ship design-related projects with Alion?s Design, Engineering and Technology Group. ?We are interested in the LCC testing in what it can do to help us improve our powering prediction computer program for SES type ships, so this basic research eort at the LCC can really benefit us. Deciding how much power to install in a high-performance ship like an SES is an important decision and there is much less existing empirical information in the literature about it than for other types of ships, adding to the risk of not getting it right. ese tests will help the whole community in this regard.? Ryan adds that the LCC is a unique facil- ity that primarily provides state of the art cavitation testing for propellers at a large scale. And, he says, it?s big. ?I haven?t seen any other water channel that is even in the same ball park as this one. Certainly there are none others in this country. e sheer size of the test capability and the channel itself dwarfs anything else like it.? [PULL-QUOTES]: e LCC is like a very large wind tunnel, but lled with water and used for high Reynolds number hydrodynamic experimentation. e overhead bridge cranes in the building are each capable of lifting 500 tons and can be ganged to lift 1,000 tons. ?We?re not trying to model an SES in its entirety, but capture the physics of a SES bow seal system.? To conduct free surface testing, the LCC has been fitted with a gate, designed at the University of Michigan. [CAPTIONS]: Lundquist1.jpg: [Darryl: is is to be the lead image.] e Large Cavitation Channel is used to investigate the physical response in the cou -pled behavior between the SES air cushion, the bow skirts, and the incoming water ow. [Darryl: Images 2 through 4 can be used in whatever order you think is best for the design/ layout.] Lundquist2.jpg: e University of Michigan experiments are investigating the behavior of nger seal ele -ments immersed in water at high speed, along with recordings of seal drag. Lundquist3.jpg: A special gate permits testing in the LCC to better understand how SES bow seals interact with the water surface. Lundquist4.jpg: e LCC test section is tted with viewing windows to allow visual observations of the ow. þÿ AA special gate permits testing in the LCC to better understand how þÿ SSEþÿ SS bow seals interact with the water surface. 42_48_Lundquistfeature_SNAME_Jan12_P3.indd 4612/22/11 3:42 PM