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Item type:Publication, Access status: without files , Analysis of unsteady flow over offshore wind turbine in combination with different types of foundationsEnvironmental effects have an important influence on Offshore Wind Turbine (OWT) power generation efficiency and the structural stability of such turbines. In this study, we use an in-house Boundary Element (BEM)—panMARE code—to simulate the unsteady flow behavior of a full OWT with various combinations of aerodynamic and hydrodynamic loads in the time domain. This code is implemented to simulate potential flows for different applications and is based on a three-dimensional first-order panel method. Three different OWT configurations consisting of a generic 5 MW NREL rotor with three different types of foundations (Monopile, Tripod, and Jacket) are investigated. These three configurations are analyzed using the RANSE solver which is carried out using ANSYS CFX for validating the corresponding results. The simulations are performed under the same environmental atmospheric wind shear and rotor angular velocity, and the wave properties are wave height of 4 m and wave period of 7.16 s. In the present work, wave environmental effects were investigated firstly for the two solvers, and good agreement is achieved. Moreover, pressure distribution in each OWT case is presented, including detailed information about local flow fields. The time history of the forces at inflow direction and its moments around the mudline at each OWT part are presented in a dimensionless form with respect to the mean value of the last three loads and the moment amplitudes obtained from the BEM code, where the contribution of rotor force is lower in the tripod case and higher in the jacket case and the calculated hydrodynamic load that effect on jacket foundation type is lower than other two cases.Publicationtype: Journal Article231 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Combined aerodynamic and hydrodynamic loads on offshore wind turbinesOffshore wind turbines are a complex mechanical systems located in severe environmental conditions. The calculation of design loads on offshore wind turbine structures is a complex undertaking involving the integration of different wind and wave load simulation methods. The aim of the thesis is the investigation of influence of the environmental conditions on the aerodynamic and hydrodynamic loads acting on fixed offshore wind turbine structures using in-house boundary element solver panMARE. So the generic NREL 5MW offshore wind turbine with the combine of three different turbines support structure typologies: monopile, tripod and jacket are chosen. Furthermore for verification of BEM results, RANSE simulations are carried out using the ANSYS CFX solver .The results comparison demonstrate the ability of the BEM solver to simulate the aerodynamic and hydrodynamic flow on a complex 3D offshore wind turbine.Publicationtype: Doctoral Thesis692 3257 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Investigation of the unsteady flow behaviour on a wind turbine using a BEM and a RANSE method(Hindawi Publishing Corporation, 2016-10-19); ; Analyses of the unsteady flow behaviour of a 5 MW horizontal-axis wind turbine (HAWT) rotor (Case I) and a rotor with tower (Case II) are carried out using a panel method and a RANSE method. The panel method calculations are obtained by applying the in-house boundary element method (BEM) panMARE code, which is based on the potential flow theory. The BEM is a three-dimensional first-order panel method which can be used for investigating various steady and unsteady flow problems. Viscous flow simulations are carried out by using the RANSE solver ANSYS CFX 14.5. The results of Case I allow for the calculation of the global integral values of the torque and the thrust and include detailed information on the local flow field, such as the pressure distribution on the blade sections and the streamlines. The calculated pressure distribution by the BEM is compared with the corresponding values obtained by the RANSE solver. The tower geometry is considered in the simulation in Case II, so the unsteady forces due to the interaction between the tower and the rotor blades can be calculated. The application of viscous and inviscid flow methods to predict the forces on the HAWT allows for the evaluation of the viscous effects on the calculated HAWT flows.Publicationtype: Journal Article262 422 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Entwicklung von panMARE als Paneelverfahren für interdisziplinäre maritime AnwendungenComputational methods based on the potential flow theory are common powerful tools for calculating the hydrodynamic behavior of lifting and non-lifting bodies. Potential flow methods can provide a valuable support for applications, where the pressure forces are dominant. Beside their short computing time, the accuracy of the results is mostly adequate for design purposes. Potential computational methods can also be used to simulate complex operation scenarios such as installation of offshore wind turbine involving different ship units. The development of computational methods for potential flow is usually carried out as problem-specific codes, i.e., certain methods are suitable only for a certain class of problems such as propeller flow or wave making resistance applications. In order to avoid this limitation, the development of a panel method panMARE was initiated several years ago at the Institute for Fluid Dynamics and Ship Theory, Hamburg University of Technology. A key point in the development of panMARE is the interdisciplinary applicability of the method for steady and unsteady flow problems under consideration of different physical models such as cavitation or influence of a free water surface. The motion of the investigated bodies can be either specified or calculated by solving the equation of motions. In addition panMARE has interfaces to various RANS solvers, thus it can be used in RANS-BEM simulations, as well as an interface to solvers that address structural and mechanical problems. Therefore, the method can be used to carry out coupled fluid-structure simulations. After explaining the theoretical background of the numerical method its capability will be demonstrated. In addition to typical shipbuilding problems such as calculation of propeller cavitation, pressure fluctuations or maneuver simulation in waves, different applications in the field of offshore wind energy will be presented.Publicationtype: Conference Paper131