To extend their application scope, towing tanks can be fitted with additional equipment such as a planar motion mechanism (PMM) or a computerized planar motion carriage (CPMC). These devices measure the hydrodynamic forces and moments acting on ships or submerged objects due to the influence of oblique inflow and enforced motions. Another possibility is to equip the towing tank with a wave generator to carry out seakeeping tests.
Solutions from Kistler for towing tank tests, ship model testing and ditching
Towing tanks play a key part in many different tests on ship models. Examples include resistance and propulsion tests that are performed with both towed and self-propelled models. Towing tanks are also used in scaled-down tests to determine a vessel's maneuvering behavior. Kistler supports researchers with multi-component force sensors and dynamometers capable of high measuring ranges as well as high and low frequencies – enabling also accurate quasi-static measurements. In some cases, acceleration is measured at the same time as force and moment, using accelerometers.
However, the applications are not limited to ships. Several specialized test centers also use their towing tanks to investigate how helicopters or airplanes will behave during an emergency landing on water. These ditching simulations involve a model aircraft with its fuselage fixed below an overhead rail.
Piezoelectric six-component force sensors or dynamometers that include triaxial piezoelectric sensors play a critical part in all these applications: they measure the induced forces and moments. Waterproof solutions are usually essential for these tests.
High force measuring range and high moment handling capability
Piezoelectric technology can work under very high loads while focusing on measurements of very small variations, thanks to the right choice of charge amplifier settings. Benefits: very high versatility, smaller sensors and easy installation.
High- and low-frequency response capability
The stiffness of piezoelectric technology allows high resonance frequencies for the mechanical assembly, so high-frequency measurements can be performed. Quasi-static measurements are also possible thanks to a charge output solution combined with high-insulation.
High measurement accuracy
Achieved thanks to high linearity and low crosstalk.
Force sensors from Kistler are hermetically sealed with a welded design to ensure that they are watertight. Cables are fitted with seals specifically designed for underwater use. Further water tightness can be achieved by welding a 1698A cable on a triaxial force sensor.