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Item type:Publication, Access status: with files , Design of a high efficiency podded drive for improved course keeping(Norwegian University of Science and Technology, Department of Marine Technology, 2024-04-04); ; ; The design of modern podded propulsion solutions is dominated by merging different, partly counteracting requirements at widely spread operating conditions. Whereas high propulsion efficiency is the key factor, large steering forces at small azimuth angles while maintaining reduced azimuth torque are of importance for a safe navigation with reasonable azimuth unit and bearing sizes. The paper introduces the approach to consider the different requirements in the early stage of a pod design of the SISHIP SiPOD 17M by application of numerical methods. Over a period of more than 25 years, the Potsdam model basin has developed optimizing methods for pods using series of model tests and numerical calculations to achieve an integral description of the interactions of propeller and housing. The numerical method is demonstrated by presenting the propeller design tool VTXopt with an optimization procedure designed as an inverse method. Enhanced numerical calculations using a RANS solver demonstrate the consequences of different fin and strut configurations on course-keeping and maneuvering. An improved steering capability with an attached fin at the cost of larger azimuth torque at small azimuth angles is observed, whereas the azimuth torque at large angles is reduced. The results are validated by model tests at the SVA Potsdam GmbH (SVA).Publicationtype: Conference Paper31 83 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Validation of a partitioned fluid-structure interaction simulation for turbo machine rotors(Taylor & Francis, 2022-05-14); ; ; ; A partitioned solution approach for the fluid-structure interaction (FSI) simulations of turbo machine rotors is presented. The in-house developed boundary element method solver panMARE is used for the fluid simulation, while the structural side is treated with the commercial finite element method solver ANSYS. The generic in-house multiphysics coupling library comana is used for the management of the implicit coupling procedure. As the first example, the KRISO container ship propeller is considered. The simulation is validated for open water test conditions assuming a rigid propeller based on the thrust and torque coefficients. Simulation results for a flexible propeller in open water are also presented. In the second example, the validation of the FSI simulation is conducted for a multilayered flexible submersible mixer based on thrust and torque coefficients and local strains. The results show a good agreement between the simulations and the experimental data for both examples.Publicationtype: Journal Article137 464 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Steady and Unsteady Hydrodynamic Loads on the Azimuth Bearing of a POD during a Crash-Stop Maneuver(The Society of Naval Architects and Marine Engineers, 2021-03); ; The crash-stop maneuver of a ship equipped with two pods produces the largest loads that the structure and azimuth bearing can possibly experience. For design purposes, a sufficiently fast and accurate determination of the loads is thus critically important. This study examines load estimation during crash-stop maneuvers based on model tests and numerical methods. Forces and moments are compared to determine the influence of different control parameters (azimuth rate, propeller number of revolution, etc.). In addition, the results of numerical simulations carried out in model- and full-scale are used to analyze the influence of the Reynolds number on the flow behavior. Results show a significant influence of the azimuth rate on the maximum forces and moments. The numerical calculations indicate a strong dependency of the flow stall behavior on the azimuth rate. The dynamic stall effect on the profileshaped parts, such as the pod strut, is shifted to a larger angle of attack compared with a steady angular position. This phenomenon is also observed during the model tests. The full-scale simulations show up to a 23% increase of the forces compared with the model-scale simulations. Thus, a detailed and careful handling of the results considered in the design process is required for the load estimation. Crash-stop maneuvers must be carried out during sea trials and regular mandatory class surveys to demonstrate compliance with safety requirements for the ship, crew, and passengers in an emergency situation. In the case of ships equipped with podded propulsion devices, these maneuvers often result in the maximum azimuth bearing load that can occur in a ship's lifetime. The stopping maneuver for ships with a conventional twin-screw propeller shaft drive arrangement is performed by turning the sense of propeller rotation into the opposite direction. By contrast, for ships equipped with podded propulsion devices, the whole unit of the podded propulsor turns around its azimuth axis until the propeller produces thrust opposite to the ship's heading direction, while the propeller turning direction remains unchanged. During the crash-stop maneuver, the lateral surface of the pod is for a short period of time almost perpendicular to the incoming flow, and consequently, the exposed surface of the pod housing to the inflow reaches a maximum value. Because the crash-stop maneuvers must be carried out at maximum ship speed, the podded drive must operate under the most severe loads during these trials. Large steering moments are required to turn the pod under these conditions, and extreme loads must be held by the azimuth bearing and then transferred to the ship structure. These loads are the design loads for the bearing and the structural components of the pod housing.Publicationtype: Journal Article213 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Numerische Untersuchung des Manövrierverhaltens von Schiffen während des StoppmanöversThis thesis focuses on the stopping behavior of ships and presents a coefficient-based approach to numerically simulate the stopping maneuver by taking into account the change of the ship speed. The maneuvering coefficients are derived from numerical calculations with a RANS method including the interaction of propeller slip stream and ship at off-design conditions. The variation of thrust deduction is covered by appropriate maneuvering coefficients and a comparison to model tests of stopping maneuvers with limited degrees of freedom allows a validation of the simulation tool.Publicationtype: Doctoral Thesis325 1293 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Steady and Unsteady Hydrodynamic Loads on the Azimuth Bearing of a POD during a Crash-Stop ManeuverPublicationtype: Conference Paper88 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Efficient Prediction of Crashback Performance of Controllable Pitch PropellersThe prediction of propeller performance in crashback con-ditions with numerical methods is challenging due to thehighly unsteady flow field, which is dominated by large-scale separation and recirculation regions. For a controllable pitch propeller (CPP), the computations should becarried out for a wide range of pitch angles. Reynolds Averaged Navier-Stokes (RANS) methods are not capable ofcapturing the most complex flow conditions. Hence, moreprecise methods like Detached Eddy Simulations (DES)should be applied. The high computational effort in conjunction with the application of these methods demands astrong limitation of the number of investigated operation points. In this paper, the computed open water characteristics curves of a CPP are compared with the experimental results. Thereby, the ranges of the open water diagram areidentified, where the RANS methods yield unsatisfying results. In these ranges, DES simulations are carried out tocapture the flow details on a propeller in crashback operation condition. DES results are shown to be in good agreement with the experimental data of the thrust and torque coefficient.Publicationtype: Conference Paper76 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , SimStopp: Entwicklung eines numerischen Modells zur Simulation von Stoppmanövern von Schiffen mit Verstellpropellern und elektrischen oder hybriden Antrieben innerhalb des Verbundprojektes OptiStopp: Optimierung des Stoppmanövers von Schiffen mit Verstellpropellern und HybridantriebenPublicationtype: Technical Report76 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Development of an Efficient Numerical Method for Coefficient-Based Simulations of Stopping ManeuversPublicationtype: Conference Paper63 - 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 Paper132 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Numerical Simulation of Propeller-Rudder Interaction for Non-Cavitating and Cavitating Flows Using Different ApproachesThe present article deals with the numerical investigation of propeller-rudder interaction. The involved simulation method is based on coupling a RANS solver and a potential-theory based panel method, where the panel method primarily handles the propeller flow and the RANS solver is used for the simulation of the complex rudder flow. Compared to full RANS simulations, this separation allows numerical investigations in a time-saving manner. In a numerical study, a rudder-propeller combination is evaluated by means of the developed simulation method for different propeller advance coefficients and rudder angles. Rudder cavitation is also adressed. The results are compared to results obtained by a full RANS simulation.Publicationtype: Conference Paper96