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1

Design of jack-up platform for 6 MW wind turbine: Parametric analysis based dimensioning of platform legs

100%
Dymarski P.
Polish Maritime Research
|
2019
|
tom 26
|
nr 2
The article presents the results of the research conducted within the framework of the project entitled WIND-TU-PLA (ERA-NET, MARTEC II), the general aim of which was to design and analyse supporting structures for wind turbines intended for operation on the South Baltic area. The research part described in the article aimed at developing a preliminary design for a jack-up platform which can operate on water areas with depth of 40 m. The main task was to determine optimal dimensions of platform legs and the radius of their spacing. Two jack-up platform concepts differing by spacing radius and hull dimensions were designed with the intention to be used as a supporting structure for a 6-MW offshore wind turbine. For each concept, the parametric analysis was performed to determine optimal dimensions of platform legs (diameter Dleg and plating thickness tleg). Relevant calculations were performed to assess the movements of the platform with parameters given in Table 1 in conditions simulating the action of the most violent storm in recent 50 years. The obtained results, having the form of amplitudes of selected physical quantities, are shown in comprehensive charts in Fig. 6 and 7. Based on the critical stress values (corresponding to the yield stress), the area was defined in which the impact strength conditions are satisfied (Fig. 14).Then, the fatigue strength analysis was performed for two selected critical leg nodes (Fig. 12). Its results were used for defining the acceptable area with respect to structure’s fatigue (Fig. 14). Geometric parameters were determined which meet the adopted criteria, Table 6. The decisive criterion turned out to be the fatigue strength criterion, while the yield point criterion appeared to be an inactive constraint
2

Numerical simulation of viscid flow around hydrofoil

100%
Dymarski P.
Polish Maritime Research
|
2006
|
tom 13
|
nr 1
This paper presents results of application of a viscid fluid model to calculate flow arounda finite-spanhydrofoil.The presented calculations were performed with the use of SOLAGA soft ware developed by this author. The used theoretical model of viscid liquid motion was described, consisted of averaged liquid motion equations and Spalart-Allmaras one-equa-tion model of turbulence. Also, a numerical model based on the finite volume method wasshortly presented. Calculation results were shown in the form of distribution diagrams of pressures, longitudinal component of velocity and longitudinal component of rotation ve-locity. Additionally, the presented characteristics of the lifting force coefficient and drag force coefficientwere compared with experimental data.
3

A numerical model to simulate the motion of a lifesaving module during its launching from the ship's stern ramp

63%
Dymarski P., Dymarski C.
Polish Maritime Research
|
2014
|
tom 21
|
nr 2
The article presents a numerical model of object motion in six degrees of freedom (DoF) which is intended to be used to simulate 3D motion of a lifesaving module during its launching from a ship using a stern ramp in rough sea. The model, of relatively high complexity, takes into account both the motion of the ship on water in changing sea conditions, and the relative motion of the ramp with respect to the ship. The motion of the ramp changes and strongly depends on its constructional and geometrical parameters. The presented model takes into account the displacement of the submerged part of the ramp, as well as its damping in the water and the interaction with the module moving on it. The results of test simulation of a module launching from the ship in still water are included
4

Computational simulation of motion of a rescue module during its launching from ship at rough sea

63%
Dymarski C., Dymarski P.
Polish Maritime Research
|
2014
|
tom 21
|
nr 3
This paper is a continuation of the work titled : “A computational model for simulation of motion of rescue module during its launching from stern ramp of a ship at rough sea”. It presents results of computer simulations of motion of a rescue module with embarked persons during its launching on rollers along stern ramp of a ship at rough sea. The simulations were conducted for a selected ship fitted with a launching ramp , for a few selected scenarios of sea conditions. It was assumed that during this operation the ship drifts across direction of wave propagation
5

Computational model for simulation of lifeboat motions during its launching from ship in rough seas

63%
Dymarski P., Dymarski C.
Polish Maritime Research
|
2012
|
tom 19
|
nr 3
This paper presents a computational model which describes motion of an object of six degrees of freedom (DoF), intended for simulation of spatial motion of one- or two- rope-sling lifeboat or rescue boat during its launching from ship in rough sea. This is a complex model which accounts for sea conditions as well as elasticity and damping properties of davit’s elements and mechanisms, rope and boat hull. Also, are presented results of example calculations for an assumed set of technical parameters of davit and boat as well as sea conditions
6

Vertical motions damping model test of a lifeboat lowered onto a flat sea surface

63%
Kniat A., Dymarski P.
Polish Maritime Research
|
2018
|
tom 25
|
nr Special Issue S1
The article presents the experiment’s results of the lifeboat model lowered with an initial speed and then released to fall onto a flat water surface. The purpose of the research is to determine the trajectory of the vertical boat motion and describe it with a mathematical model. This is closely related to determining the damping factor since the vertical motion is damped and the lifeboat gets balanced and stops moving after some time. The procedure of selecting parameters in the mathematical model to adjust to the results of the experiment was described in details. The summary describes the imperfections of the presented damping model and their probable causes
7

Design of structure of tension leg platform for 6 MW offshore wind turbine based on fem analysis

51%
Zywicki J., Dymarski P., Ciba E., Dymarski C.
Polish Maritime Research
|
2017
|
tom 24
|
nr Special Issue S1
The article presents the calculation and design stages of the TLP platform serving as a supporting construction of a 6 MW offshore wind turbine. This platform is designed to anchor at sea at a depth of 60 m. The authors presented the method of parameterization and optimization of the hull geometry. For the two selected geometry variants, the load and motion calculations of the platform subjected to wind, wave and current under 50-year storm conditions were performed. The maximum load on the structure was determined in these extreme storm conditions. For these loads, the MES calculation of the designed platform was performed for the selected variant. Authors have presented a method for calculating maximum wind, wave and current stresses on the structure during the worst storm in the past 50 years. For these loads the MES endurance calculations of the designed platform were made. Based on the results of these calculations, the required structural changes and recalculations have been made in succession to the structural design of the platform, which meets the design requirements and has the required ad hoc strength. The article contains stress analysis in „difficult” nodes of constructions and discusses ways of solving their problems. The work is part of the WIND-TU-PLA project from the NCBR Research Agreement (Agreement No. MARTECII / 1/2014)
8

Design and strength calculations of the tripod support structure for offshore power plant

51%
Dymarski C., Dymarski P., Zywicki J.
Polish Maritime Research
|
2015
|
tom 22
|
nr 1
The support structure being the object of the analysis presented in the article is Tripod. According to the adopted assumptions, it is a foundation gravitationally set in the water region of 60 m in depth, not fixed to the seabed, which can be used for installing a 7MW wind turbine. Due to the lack of substantial information on designing and strength calculations of such types of structures in the world literature, authors have made an attempt to solve this problem within the framework of the abovementioned project. In the performed calculations all basic loads acting on the structure were taken into account, including: the self mass of the structure, the masses of the ballast, the tower and the turbine, as well as hydrostatic forces, and aero- and hydrodynamic forces acting on the entire object in extreme operating conditions.
9

Stability analysis of the floating offshore wind turbine support structure of CELL SPAR type during its installation

51%
Dymarski P., Dymarski C., Ciba E.
Polish Maritime Research
|
2019
|
tom 26
|
nr 4
The article presents the results of selected works related to the wider subject of the research conducted at the Faculty of Ocean Engineering and Ship Technology of the Gdansk University of Technology, which concerns design and technology of construction, towing, and settlement on the seabed, or anchoring, of supporting structures for offshore wind farms. As a result of this research, several designs of this type of objects were developed, including two stationary types: gravitational and Jack-up, which are placed on the seabed, and two floating types: TLP and SPAR, anchored with tendons and anchors in the form of nailed or suction piles. Below presented is the stability analysis of the new floating CELL SPAR type support structure for offshore wind turbines during its installation in waters with a depth of over 65 m
10

Effective method for determining environmental loads on supporting structures for offshore wind turbines

51%
Dymarski P., Ciba E., Marcinkowski T.
Polish Maritime Research
|
2016
|
tom 23
|
nr 1
This paper presents a description of an effective method for determining loads due to waves and current acting on the supporting structures of the offshore wind turbines. This method is dedicated to the structures consisting of the cylindrical or conical elements as well as (truncates) pyramids of polygon with a large number of sides (8 or more). The presented computational method is based on the Morison equation, which was originally developed only for cylindrically shaped structures. The new algorithm shown here uses the coefficients of inertia and drag forces that were calculated for non-cylindrical shapes. The analysed structure consists of segments which are truncated pyramids on the basis of a hex decagon. The inertia coefficients, CM, and drag coefficients, CD, were determined using RANSE-CFD calculations. The CFD simulations were performed for a specific range of variation of the period, and for a certain range of amplitudes of the velocity. In addition, the analysis of influence of the surface roughness on the inertia and drag coefficients was performed. In the next step, the computations of sea wave, current and wind load on supporting structure for the fifty-year storm were carried out. The simulations were performed in the time domain and as a result the function of forces distribution along the construction elements was obtained. The most unfavourable distribution of forces will be used, to analyse the strength of the structure, as the design load
11

Technology concept of TLP platform towing and installation in waters with depth of 60 m

51%
Dymarski C., Dymarski P., Zywicki J.
Polish Maritime Research
|
2017
|
tom 24
|
nr Special Issue S1
The ar ticle is par t of the design and research work conducted at the Gdansk University of Technolog y, Faculty of Ocean Engineering and Ship Technology, in cooperation with a number of other research centres, which concerns offshore wind farms planned to be built in the Polish zone of the Baltic sea in the next years. One of most difficult tasks in this project is building suitable foundations for each power unit consisting of a tower and a wind turbine mounted on its top. Since the water regions selected for building those wind farms have different depths, there was need to study different possible technical variants of this task, with the reference to both the foundation structures themselves, and the technology of their transport and setting, or anchoring. The article presents the technology of towing, from the shipyard to the setting place, and installation of the foundation having the form of a floating platform of TLP (Tension Leg Platform) type, anchored by tight chains to suction piles in the waters with depth of 60 m
12

Searching for critical conditions during lifeboat launching - simulations

51%
Dymarski C., Dymarski P., Kniat A.
Polish Maritime Research
|
2017
|
tom 24
|
nr Special Issue S1
The article describes numerical simulations of the process of lifeboat launching at the ship’s side. The research aimed at finding the values of ship motion parameters which appear to be most dangerous for people in the lowered lifeboat due to the generated accelerations. The simplified model of ship hull motion adopted at this research stage bases on a superposition of harmonic motions with given amplitudes and periods in six degrees of freedom. The range of the amplitude of motion for each degree of freedom corresponds approximately to that of possible motion of the PANAMAX type ship on the Baltic sea. In total, 120 960 cases of ship hull motion were examined
13

A method for the accurate numerical prediction of the tip vortices shed from hydrofoils

45%
Flaszynski P., Szantyr J. A., Biernacki R., Dymarski P., Kraskowski M.
Polish Maritime Research
|
2010
|
tom 17
|
nr 2
The possibly accurate numerical prediction of the detailed structure of vortices shed from the tips of hydrofoils is an important element of the design process of marine propellers. The concentrated tip vortices are responsible for the propeller cavitation erosion and acoustic emission. The purpose of the project described in this paper was to develop the numerical method for prediction of the tip vortex structure. In the course of the project the numerical calculations were confronted with the results of experimental measurements. This led to creation of the specific method of construction of the computational grid and to selection of the optimum turbulence model. As a result the reliable method for the accurate numerical prediction of the concentrated tip vortices for different hydrofoil geometry and flow conditions has been developed and validated. This method enables elimination of the unfavourable phenomena related to the tip vortices in the course of the propeller design calculations
14

An experimental and numerical study of the vortices generated by hydrofoils

45%
Szantyr J. A., Biernacki R., Flaszynski P., Dymarski P., Kraskowski M.
Polish Maritime Research
|
2009
|
tom 16
|
nr 3
The article presents the results of the research project concerning the process of formation of the tip vortices shed from hydrofoils of different geometry in different flow conditions. Three hydrofoils resembling the contemporary marine propeller blades have been selected for the study. The experimental part of the project consisted of the LDA measurements of the velocity field in three cross-sections of the vortex generated by the hydrofoils in the cavitation tunnel. The numerical part of the project consisted of calculations of the corresponding velocity field by means of three computer codes and several selected turbulence models. The comparative analysis of the experimental and numerical results, leading to the assessment of the accuracy of the numerical methods, is included
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