A contra-rotating marine current turbine has a number of attractive features: near-zero reactive torque on the support structure, near-zero swirl in the wake, and high relative interrotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing t...

In order to harness the kinetic energy of marine currents, we propose a novel ocean-current turbine with a horizontal axis. The turbine can be moored to the seabed and function similarly to kites in a water flow. To operate such turbines in a marine current, the resulting rotor torque needs to be canceled. Therefore, the proposed turbine is designed with a float at its top and a counterweight a...

In order to solve the towing problem on water of the open caisson in the construction of the large scale bridge efficiently, combining with the towing operation project, the dragged open caisson and environmental data, etc. we design and produce the open caisson physical model and configure the test environment, use the force cell to collect real-time experimental data, analyze and demonstrate ...

In this paper a nonlinear thrust controller for fixed pitch marine propellers with torque loss estimation and an antispin strategy is presented. The controller, designed to operate in the four-quadrant plane composed by the shaft speed and the vessel speed, is a combination of a thrust controller developed for calm/moderate sea states and an anti-spin strategy to reduce power peaks and wear-and...

In this paper a nonlinear thrust controller for a fixed pitch marine propeller with torque loss estimation and an anti-spin strategy is presented. The controller, designed to work in the four-quadrant plane composed by the shaft speed and the vessel speed, is a combination of a thrust controller designed for calm sea conditions and an anti-spin strategy to reduce power peaks and wear-and-tear i...

Hydraulic turbine discharges in low-head hydroelectric plants, and plants with awkward intake geometries can be measured relatively easily with the Acoustic Scintillation Flowmeter (ASFM). The ASFM is non-intrusive, and may be deployed in intake gate slots in a straightforward manner, lending itself to multiple measurements in the same plant. Examples of measurements in two generating stations ...

Flow around a rowing blade is a very complex phenomenon, involving unsteady three-dimensional flow with violent motion of the free surface. However, in the literature, forces acting on blades are modelled using extreme and dubious simplifications. The aim of the present study was to evaluate the influence of free surface and unsteadiness (two physical characteristics that are commonly neglected...

B-spline curves and surfaces and their suitability for ship hull surface definition are discussed. A comparison with other curve and surface definition methods, e.g., cubic splines, Bézier curves, parabolic blending is given. Their use both for ab initio curve and surface generation and for fitting existing offset data is discussed. Comparisons of the data storage requirements are made. The uti...

This paper reviews current problems in intact stability criteria, including the development of new generation intact stability criteria at the IMO (International Maritime Organization), the activities of the ITTC(International Towing Tank Conference) ‘s Specialist Committee on Stability in Waves (SiW) and relevant international researches as the backgrounds of the SCAPE Committee (Strategic Res...