What is a towing tank (ship model basin)?
My interpretations:
A large tank (ours is 80m*2.55m*1.8m for length, width and depth) filled with water, and a carriage is mounted across the tank running on the rails on the tank walls. A wave-maker is mounted at one end of the tank to generate wavy environment for testing, and a beach is installed on the other end to help reducing the reflective waves.
During tests, ship model(s) (or any marine structures) is connected to the carriage and towed along the tank with a given speed in calm water or waves generated by the wave-maker. The loads and motions of the model are recorded by specially-made devices such as dynanometer, gyroscope and accelerometers.
We do tests on wave-energy devices as well, check it up here!
Towing tank of the Richmond Field Station Physical Testing Facility, UC Berkeley
Towing tank carriage
Design and Fabrication of Adjustable Towing Frame
Structure is needed to attached the model ship to the carriage, and host necessary measuring devices (such as dynanometer, potentiometer) and controller. In addition, we are doing things differently here: towed two model ships at once with adjustable formation. Therefore, a lot of thoughts have been invested into designing and fabrication of such novel towing frame.
Solidworks drawing of the towing frame
Towing frame placement on carriage
On-frame Arduino Uno controller
Potentiometer for sinkage measurements
On-frame Whitstone bridge panel - Phidget 1046 bridge panel
Ship Motion Analysis Radio Transmission (SMART) system
As ships travel on calm-water surface, the uneven longitudinal distribution of hydrodynamic pressure along the hull body will result in vertical change of draft and pitching of the vessel, which are called sinkage and trim, respectively. In the towing tank experiments, sinkage is measured by potentiometer, that the linear motion of the vessel is transformed into the voltage signal and captured by Arduino Uno. In the meantime, the trim angle is measured by a wireless gyroscope/accelerometer, called the Ship Motion Analysis Radio Transmission (SMART) system, which is made with Arduino-based micro-electronic parts.
The main components of the SMART system are:
Computer program for data sampling and post-processing are written in MATLAB and Python, a Github website is coming soon!
Illustration of sinkage and trim
Sensor module of the SMART system
Receiver module of the SMART system