Simulation and Experimental Studies of a Multi-Tubular Floating Sea Wave Damper

Abstract

This article explores the issue of shore protection from sea waves and has presented the main methods used for coastal protection. It discusses the construction and operation of the multi-tubular floating sea wave damper that has been developed at the Maritime University of Szczecin by Professor Bolesław Kuźniewski. This paper presents the results of the research project aimed at creating and examining a prototype of the device. The research aimed to confirm the two hypotheses: "the largest damping force should occur when the damping units are placed at an optimal distance equal to half the length of the wave to be damped" and "a compensation of the horizontal forces caused by the rippling of water should occur in the damping device". Simulation studies of the behaviour of the device's buoyancy elements when floating on waves were performed using the ANSYS AQWAWB and AQWA software. The buoyancy components were modelled as TUBE elements with a diameter of 0.11 m and a length of 1.5 m and as triangular and square surface elements. The results of the experimental research and the computer simulation of the operation of the prototype device have also been presented. The external conditions adopted corresponded to the frequency of a wave equal to 0.807 Hz and to the wave height in front of the device which was equal to 0.1 m. Experimental studies were conducted in an auxiliary model basin with dimensions of 60 m × 7 m × 3.12 m at the Ship Hydromechanics Division, Ship Design and Research Centre (CTO S. A.) in Gdańsk (Poland). The study recorded the distribution of the vertical and horizontal forces acting on the prototype device as well as the wave height both in front of and behind the device. Both hypotheses were proven. Simulation and experimental studies have been summarised. A proposal for future works has also been presented.

Importance Analysis of Components of a Multi-Operational-State Power System Using Fault Tree Models

“…If a vessel is equipped with both electrically driven and main propulsion engine-driven trawl and net winches, the vectors (24) and (25) will take their respective forms [27]: 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0] (26) Figure 12 shows the Vesely-Fussell importance measure of the system components during the trawling operation. position, a coupled trawl winch installed in the system, or a decoupled net winch, both shaft-driven, and noninstalled electrical winches, the vector w  of conditional events takes the following form [40]: 0 , 0 , 0 , 1 , 1 , 1 , 1 , 1 , 1 , 1 , 0 , 0 , 1 , 1 , 1 , 1 , 0 , 1 [ ] 0 , 0 , 0 , 0 , , , , , , , , 0 , 0 , , , , , 0 , [ 8 7 7 7 6 6 5 4 3 3 2 1 = = a c b a b a b a b a b w w w w w w w w w w w w w …”

“…Many complex technical systems are composed of similar or identical (analogous) basic components. Examples of such systems are ship's power systems [23][24][25]. The paper analyses the power system, understood as the whole system composed of the subsystems of electric energy production, ship propulsion, and the technological process.…”

Simulation-Based Methodology for Determining the Dynamic Strength of Tire Inflation Restraining Devices

“…There are a number of simulation-based methodologies that could be used for the analysis of different operational aspects of mechanical systems, including reliability and safety, as well as processes in solid-state materials and in fluids. Such tests might be performed in general by means of the Monte Carlo [27,28] method supported by Fault Tree Analysis (FTA) [29,30], Reliability Block Diagrams (RBD) [31,32], Accelerated Life Testing (ALT) [33], Computational Fluid Dynamics (CFD) [34,35] or the Finite Element Method (FEM) [24,36]. Following the specificity of the analyzed situation (explosion is rapid and extremally dynamic) and of the system that was taken into account (inflation restraining device to which solid-state mechanics are applied), the FEM-based analysis was taken into account as a candidate for the core of the proposed methodology.…”

A Numerical Analysis of the Working Machine Tyre Inflation Process to Ensure Operator Safety

“…An explosion is a rapid increase in volume and an energy release, and is usually accompanied by the generation of high temperatures, pressure, radiation emission (e.g., sparks) and acoustic waves. Explosions occur due to rapid exothermic chemical reactions (e.g., combustion), runaway chain reactions and rapid physical phenomena (e.g., steam boiler and gas pressure vessel explosions) [1,2].…”