With Instrumentation Upgrades and Modernizations, Virginia Tech’s Towing Tank Facility Is Ready for Engineering Research | VTX

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Tucked deep in the basement of Norris Hall, Virginia Tech’s 60-year-old tow tank was in desperate need of a facelift. The basin and its towing trolley, mainly used for ship strength research, were beginning to age.

In late 2018, Associate Professor Christine Gilbert and Professor Craig Woolsey of the Department of Aerospace and Oceanic Engineering Kevin T. Crofton secured $620,000 from the Office of Naval Research through the Research Instrumentation Program at the University of defense. The resulting instrumentation upgrade modernized the aging towing tank to provide Virginia Tech with a unique test facility to perform innovative, non-traditional experiments that will serve the U.S. Department of Defense.

One of more than a dozen university towing tanks in the United States, the Virginia Tech Enhanced Tank provides undergraduate and graduate engineering students with valuable experience in state-of-the-art facilities, training in cutting-edge technologies and, finally, the opportunity to work to advance military research, which plays an essential role in the development of the workforce. The facility is located near several U.S. Navy and commercial installations in the Mid-Atlantic region, including Washington, D.C. and Norfolk, which regularly hire Virginia Tech engineers to support the Department of Defense mission.

Experimental towing tank facilities are used by naval architects and engineers to conduct physical model experiments in a controlled environment. Although they vary in size and length, these rigs typically consist of a tank several meters long with a tow dolly mounted on rails above the tank, which pulls a model through the water at high speed. Researchers can test small-scale models of ships and vehicles and ocean engineering instruments, and capture hydrodynamic data such as drag, lift, and flow force while studying the effects of waves on the vehicle structure.

“Students are going to be able to use the new towing tank facility to gain fundamental knowledge – whether they get this opportunity through undergraduate or graduate research projects, independent study, and engineering design. curricular or competitive,” Gilbert said. “Work experience on tank towing experiments at Virginia Tech is valuable professional training for experimental work performed in the field and in naval laboratories.”

Smoother movement, precisely controlled speed

Virginia Tech began working with DLBA (a division of Gibbs & Cox) in partnership with Edinburgh Designs on commercial studies for the dolly upgrade beginning in 2019. The old tow dolly was removed and replaced with a high-speed single frame design that no longer requires researchers and students to climb on the cart. The cart is now remote-controlled, equipped with cameras for surveillance, and boasts smoother cart movement along its tracks and more precisely controlled cart speed.

The cart itself is capable of a constant maximum speed of 7 meters per second (or 23 feet per second). The carriage is powered by a belt drive system with a large electric motor on each rail. The brakes are electromagnetic, providing sufficient braking force for heavy acceleration and deceleration loads. The main structure of the cart is constructed using ITEM aluminum extrusions in combination with large custom aluminum parts. These extrusions make it easy to build and modify breadboards.

Other additions to the towing tank include a dedicated data acquisition system and a suite of new sensors for experiments, such as dynamometers, accelerometers, potentiometers, wave probes, inclinometers and pressure sensors. .

A newly installed vertical planar motion mechanism, designed by DLBA and built by Virginia Tech, facilitates controlled motion experiments for a model by prescribing heave and pitch motions. The mechanism, manipulated with two linear actuators, will have controllable lifting movements with a range of 64 centimeters.

Although Virginia Tech’s tow tank is relatively small in size—the basin is 98 feet long, 6 feet wide, and 4 feet deep—the cart’s top speed is more than twice as fast as tow tanks of similar size. New enhancements to the facility enable precision measurements, making the facility well suited for small-scale ocean vehicles and platforms, including small watercraft, autonomous underwater vehicles, and biomimetic robots. Experimental capabilities include strength and propulsion testing, linear and non-linear maneuvering experiments, and development of sea-keeping models.

“Maintaining high-quality facilities to support formal and research-based education is essential,” Gilbert said. “In particular, the upgraded facility will help validate new analytical models for submerged vessels maneuvering in waves or computational fluid dynamics models for studying the slapping of small craft in waves.”

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