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January 2012 www.sname.org/sname/mt e experimentation being conducted at the LCC impressed Ryan. ?e tests tack- led extremely dicult technical areas with creativity and superb attention to technical and theoretical issues to provide the best possible results. The knowledge brought by the test team, primarily from University of Michigan, precluded major problems and enabled rapid progress toward the test objectives. e team had an excellent mix of skill sets in hydrodynamics, mechani- cal, computer, electrical, and model testing to solve the design and development chal- lenges quickly and eectively.? e exibility for the LCC to be able to con- duct free surface testing is remarkable, Ryan says. ?With the ability to conduct continuous testing plus the direct underwater visual view- ing of the test xture, we could see behavior of the surface eect ship bow seal that has never been revealed before?a big step forward in understanding the hydrodynamics of these complex seal systems. e free surface capa- bility opens up whole new possibilities for continuous testing, meaning that lengthy data sets can be gathered quickly.? e professional community involved in naval architecture and marine engineering benets from the LCC, Ryan says. ?e LCC is truly a national resource. Even if it doesn?t get 100% utilization, when it is needed there is no equal. e navy must retain this capa- bility if we are to maintain our leadership in submarines and other critical technologies.? Experimentalists and numerical scientists ?e work put up by the team of University of Michigan along with the sta at the Large Cavitation Channel facility is simply extraordinary,? says Pere-Andreu Ubach de Fuentes, assistant director of CIMNE (International Center for Numerical Methods in Engineering) in Barcelona, Spain. Fuentes attended the ONR-sponsored dem- onstration of the LCC SES skirt testing. ?It is a remarkable eort with experimentalists coop- erating with numerical scientists in order to raise the level of understanding of the physical response in the coupled behavior between the SES air cushion, the bow skirts, and the incom- ing water ow. From a numerical approach standpoint, I am very excited at the prospect of obtaining very high quality experimental results of a problem as complex as this one.? e facility is impressive, capable and well run, says David Lavis, senior vice pres- ident and general manager of CDI Marine Company - Band Lavis Division, and an expert in high-speed ship and craft design. Lavis served as chairman of BLA for 21 years before that company?s 1998 acquisition by CDI Marine Company. He has held manage- ment positions with the Marine Division of Aerojet General, Bell Aerospace Textron, and Saunders Roe in the U.K. ?I know of no comparable facility in capability,? Lavis says. ?I have seen cavita- tion tunnels in Hamburg Germany, MARIN Wageningen in Holland, and Marintek in Trondheim, Norway and would guess that they do signicant commercial work at much less cost, albeit with smaller/less capable facilities.? ?e demonstration of the set up was very impressive and gave unprecedented sh-eye views of the behavior of nger seal elements immersed in water at high speed along with recordings of seal drag,? Lavis says. The LCC is a unique facility?at least within the United States?capable of run- ning large models at high test speeds in scale cavitation conditions, says Robert Moore, an aeronautical engineer with Textron Marine & Land Systems for 33 years, now retired and working for Textron as a consultant on the T-Craft project. ?I do not think there is any other facility that can come close to the com- bination of Froude number, Reynolds number and cavitation number that can be achieved simultaneously in the LCC,? Moore says. ?Compared with other free-surface chan- nel or flume facilities, the test speeds are higher, making it usable for research into the hydrodynamics of high speed craft such as Surface Eect Ships,? Moore says. ?Compared with a towing tank, you can run continu- ously, and the ability to view the test article for extended periods of time from above or below the water is extremely valuable.? ?The planned testing of bow seals made from dramatically dierent materials could also be very valuable in understanding the physical phenomena at play in the interaction of seal fabric with the water surface,? Moore says. Moore says the facility provides a unique capability to run continuously, and vary parameters such as cushion pressure, cushion height etc. while observing the model at close quarters from above water or under water. ?For the test conditions we þÿ O pOPEþÿ rRATI þÿ nNG S þÿ pPECIFICATIO þÿ n sNS þÿ TThe Large þÿ CCavitation þÿ CChannel is a vertical plane, closed recir- culating 1.4 million gallon, variable-speed, variable-pressure channel with the lower half submerged in a 2.5 million gal- lon water-lled trench, with numerous acoustic treatment features. þÿ TThe facility has a 6:1 contraction ratio, aeration/deaer- ation system, lter system (5-micron), temperature control, stainless steel shell, and low turbulence (0.1%). þÿ TThe high- speed capability ranges up to 50 ft./s. þÿ TThe large test chamber is 10 ft. by 10 ft. in cross section with a 13.1 m (43 ft.) working length. Pressure in the test section ranges from less than atmo- spheric to four times atmospheric pressure, the equivalent of water approximately 100 ft. in depth. To conduct free surface testing, the LCC has been tted with a gate, designed at the University of Michigan. 42_48_Lundquistfeature_SNAME_Jan12_P3.indd 4712/22/11 3:42 PM