An article with controllable wettability includes a substrate and a layer of a composite material supported on the substrate. The layer has an exposed surface and the composite material includes particles that have controllable polarization embedded fully or partially in a matrix. A controller is operable to selectively apply a controlled variable activation energy to the layer. The controllable polarization of the particles varies responsive to the controlled variable activation energy such that a wettability of the exposed surface also varies responsive to the controlled variable activation energy.

This disclosure relates to a system for reducing cavitation at a surface that moves relatively with respect to a first fluid. The system comprises a degasser configured to at least partially degas a second fluid. The system also comprises a reservoir in communication with the degasser and configured to house the at least partially degassed second fluid, the reservoir having an outlet that is arranged for directing the second fluid towards the surface. The system is configured such that the directing of the at least partially degassed second fluid towards the surface forms a boundary layer at the surface. The boundary layer is adapted to at least partially increase the negative pressure required to initiate cavitation at the surface so as to reduce the occurrence of cavitation during such relative movement.

A cross-flow fan includes a plurality of fan blades provided to be circumferentially spaced apart from each other. The fan blade has an inner edge portion arranged on the radially inner side to/from which air flows in/out, and an outer edge portion arranged on the radially outer side to/from which air flows in/out. Fan blade has a blade surface extending between the inner edge portion and the outer edge portion. The blade surface includes a pressure surface arranged on the rotation direction side of the cross-flow fan and a suction surface arranged on the back side of the pressure surface. When cut along a plane orthogonal to the rotation axis of the cross-flow fan, the fan blade has a blade cross-sectional shape in which a concave portion concave from the pressure surface is formed.

Disclosed herein is a foldable canoe. More particularly, the foldable canoe is configured such that it is constructed by folding a single synthetic resin sheet along a folding line without using a separate structural frame, and after the use of the canoe, the synthetic resin sheet can be completely folded along the folding line to form a compact shape, thus reducing the volume and length of the canoe, thereby facilitating transportation and storage of the canoe.

A fluid hinge includes a first part of a two-part element including a planar surface of a trim tab and a second part of the two-part system having at least one bracket secured to the hull of a watercraft and the first and second parts of the two-part element are not physically coupled together. It also provides at least one bracket secured to the hull on which the planar surface of the trim tab may rest and the at least one bracket not taking any load from the planar surface except at rest to keep the planar surface from descending below the horizon of the hull.

A ship and associated methods of operation. In an example embodiment, a method of transporting includes providing multiple vessels each having a hull defining an air cavity over a water surface. Different ones of the vessels are loaded with material destined for different end locations. The vessels are connected to one another with rigid couplings to effect tandem movement of the multiple vessels over water as one ship while permitting each vessel to undergo changes in pitch. The vessels are transported to a first destination and one or more of the vessels are disconnected from the ship.

Disclosed is a vessel including a hull and a system providing an air lubricating layer between the bottom and water, including a cavity defined by sidewalls, a top wall and an interface plane, in which water mixes with air due the Kelvin Helmholtz effect. The sidewalls extend from a dagger-shaped nose section at the front end to the rear end of the cavity and diverge so a distance between the sidewalls increases along the length of the cavity when going in a rearward direction. The diverging cavities provide a stable air lubrication layer that covers a relatively large area of the bottom, so the number of cavities can be reduced. The alignment of the diverging cavities with the streamlines has relatively large tolerances so construction is simplified and can be carried out in a cost-effective manner. The diverging sidewalls lead to reduced formation of vortices and reduced drag.

The invention provides an apparatus that attaches to a hull of a boat to disrupt water flow around the hull such that a wake created behind the boat is larger, differently positioned, and/or differently shaped. In some embodiments, the apparatus is removably attached to the hull by one or more suction cups. The wake shaping apparatus can include a blade and be configured such that an angular orientation of the blade is adjustable. In certain embodiments, the wake shaping apparatus is inflatable.

In a method of ice distribution and data processing for ship ice resistance experiment in broken ice field, the ice floe is uniformly distributed in the broken ice field before each ship ice resistance experiment with eliminating the mutually overlapped broken ice to make it close to the experimental design working condition, and independent repeated experiments are carried out on each ship ice resistance experiment to reduce the influence of accidental factors; after finishing the experiment, the experimental data are divided into intervals and the experimental data corresponding to unreasonable subdomains are eliminated by mathematical statistics, and the uncertainty analysis is carried out; image correction is carried out for pictures of in broken ice field in the pre-experimental data, and the pictures are divided to obtain subdomain pictures to calculate the actual coverage rate of each subdomain; the ice resistance in the experimental data corresponding to each remaining subdomain is modified.

A novel mechanism for reducing boundary layer friction and inhibiting the effects of uncontrolled fluid turbulence and turbulent layer separation, thus reducing the body drag, kinetic energy losses and lowering engine and pump fuel consumption is proposed. It steps on the type of turbulence observed in the so-called in fluid dynamics “drag crisis”. Plurality of device shapes and plurality of devices producing the wanted pure form of even plurality of counter-rotating vortices extending into the flow, i.e. tubes, are presented and discussed in detail, contrasting with the prior art. Configurations of multiple devices for the purposes of drag and fuel reduction, including their simulations and experimental results are put forward. Additional embodiments of the resulting tubes disclose use on aircraft or vessel control surfaces as stall inhibitors, use in wind turbines as dynamic range extenders, as well as use in turbines in efficient cooling mechanisms.