Maritime Research Institute Netherlands

About: Maritime Research Institute Netherlands is a nonprofit organization based out in Wageningen, Netherlands. It is known for research contribution in the topics: Turbulence & Computational fluid dynamics. The organization has 200 authors who have published 279 publications receiving 4382 citations. The organization is also known as: MARIN.

The behaviour of flexible risers in waves

Abstract: In this paper results of flexible riser model tests are discussed and compared with results of time domain simulations for regular and irregular wave conditions with current. The model tests were performed at the Maritime Research Institute Netherlands (MARIN) with a large scale riser model. Special attention was given to the correct phasing between riser motions and irregular waves. The calculations were performed with the MARIN riser analysis program DYNAFA.

Roughness Effects on the VIM Response of Deep-Draft Semi-Submersible Platforms

Abstract: Experiments on the Vortex-Induced Motions (VIM) acting on deepdraft Semi-Submersible (SS) platforms were carried out in a towing tank in order to investigate the roughness effects on the surface of two different 1:100-scale models. Both models were built based on the typical SS geometry with four columns and each model with the same arrangement of four pontoons in closed configuration. The models were elastically supported by means of a set of linear springs, which also provided low structural damping, and then submitted to a range of towing velocities in the reduced velocity range from 4 up to 25 covering the Reynolds numbers from 7,000 up to 80,000. Three different levels of roughness were tested: 1) bare models; 2) intermediate level of roughness and 3) high level of roughness. For the SS with rounded square columns, no significant differences were observed in terms of the VIM response For the SS platform with circular columns, some difference on the transverse and yaw motions were observed. These results seem to confirm two important aspects: the important role played by the separation point near the rounded corners of the rounded-square columns and the roughness effect on the boundary layers of the circular columns at the Reynolds numbers just below the critical regime. The results presented herein are part of a more complete campaign of experiments carried out within the VIM JIP which is run by MARIN and USP. Also within this campaign, the effect of column design on VIM response was investigated using the same models. Those results can be found in a complementary paper in this conference.

Calculation-methods of hydrodynamic coefficients of ships in shallow water

Abstract: Etude en vue d'etablir une relation entre les resultats de calcul obtenus a partir de plusieurs techniques disponibles et les resultats experimentaux. Dans ce but des essais a oscillations forcees ont ete realises par le laboratoire d'hydromecanique du departement de l'Universite de technologie de Delft. Les coefficients hydrodynamiques ont ete etablis a la fois pour les directions horizontales et verticales du mouvement dans le cas d'eau dont les profondeurs sont differentes

A hardware-in-the-loop wave-basin scale-model experiment for the validation of control strategies for floating offshore wind turbines

Abstract: This paper presents a new hardware-in-the-loop methodology for wave-basin scale-model experiments about floating offshore wind turbines and its application as a tool for the validation of control strategies. In the hardware-in-the-loop experiments, the physical Froude-scaled wind turbine model used in conventional scale-model tests is replaced by a numerical model, measurements and a multi-fan actuator. As usual, properly-scaled waves are generated in the wave basin and the floating platform is simulated by means of a scale-model. The hardware-in-the-loop methodology was used to recreate the interaction between the collective pitch controller and the platform pitch mode that, often observed in numerical studies. In addition, the blade-root load measurement available in the numerical model of the rotor was used to implement an individual pitch control strategy. Different from in conventional experiments, the hardware-in-the-loop methodology allows to recreate a realistic three-dimensional wind field that was used to demonstrate the effectiveness of the individual pitch control. The improved emulation of the rotor loads and wind field make the hardware-in-the-loop experimental methodology an effective tool for the development and validation of control strategies for floating offshore wind turbines.