Dynamic Responses of the State-of-the-Art Floating System Integrating a Wind Turbine With a Steel Fish Farming Cage: Model Tests vs. Numerical Simulations

2021 ◽  
Author(s):  
Yu Lei ◽  
Xiang Yuan Zheng ◽  
Hua-dong Zheng
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Wind Turbine ◽  
Fish Farming ◽  
Dynamic Responses ◽  
Drag Coefficients ◽  
Free Decay ◽  
Floating System ◽  
Simulation Results ◽  
Decay Tests

Abstract This work is dedicated to comparing the experimental and numerical results of the dynamic responses of a novel floating system integrating a floating offshore wind turbine with a steel fish farming cage (FOWT-SFFC) under wind and wave loadings. The patents of this floating system have been successfully licensed recently in China and USA. The experimental study is carried out in the Ocean Basin of Tsinghua Shenzhen International Graduate School, with a Froude scaling of 1:30. A small commercial wind turbine is used to produce the scaled wind loads on FOWT-SFFC in terms of the similarity of thrust force. In this paper, the setup of model tests is described first. Second, a numerical model of prototype FOWT-SFFC is built in the software OrcaFlex. Then, this numerical model is calibrated and updated by the results of free decay tests and static offset tests in the basin. The numerical model also adopts three sets of drag coefficients. Finally, the experimental results of FOWT-SFFC under a variety of load cases are presented and compared with the numerical simulation results. They include seakeeping tests for hydrodynamic motion response amplitude operators (RAOs) and dynamic responses corresponding to normal operating and survival conditions. The numerical simulation results show that, though they are in good agreement with model test data especially on time records of dynamic responses, they are sensitive to the selection of drag coefficients particularly on extreme values and low-frequency spectral contents. Appropriate drag coefficients are suggested to be used in the numerical model for a specific environmental condition. Drag coefficients benchmarked from the free decay tests may not be suitable for moderate and harsh wave conditions.

Calibration of a Time-Domain Hydrodynamic Model for A 12 MW Semi-Submersible Floating Wind Turbine

2021 ◽  
Author(s):  
Carlos Eduardo Silva de Souza ◽  
Nuno Fonseca ◽  
Petter Andreas Berthelsen ◽  
Maxime Thys
Keyword(s):  
Numerical Model ◽  
Wind Turbine ◽  
Time Domain ◽  
Quadratic Model ◽  
Wave Loads ◽  
Frequency Wave ◽  
Load Models ◽  
Wave Drift ◽  
Floating Wind Turbine ◽  
Decay Tests

Abstract Design optimization of mooring systems is an important step towards the reduction of costs for the floating wind turbine (FWT) industry. Accurate prediction of slowly-varying horizontal motions is needed, but there are still questions regarding the most adequate models for low-frequency wave excitation, and damping, for typical FWT concepts. To fill this gap, it is fundamental to compare existing load models against model tests results. This paper describes a calibration procedure for a three-columns semi-submersible FWT, based on adjustment of a time-domain numerical model to experimental results in decay tests, and tests in waves. First, the numerical model and underlying assumptions are introduced. The model is then validated against experimental data, such that the adequate load models are chosen and adjusted. In this step, Newman’s approximation is adopted for the second-order wave loads, using wave drift coefficients obtained from the experiments. Calm-water viscous damping is represented as a linear and quadratic model, and adjusted based on decay tests. Additional damping from waves is then adjusted for each sea state, consisting of a combination of a wave drift damping component, and one component with viscous nature. Finally, a parameterization procedure is proposed for generalizing the results to sea states not considered in the tests.

scholarly journals NUMERICAL SIMULATION OF TSUNAMI CURRENTS

2011 ◽  
Vol 1 (32) ◽  
pp. 6 ◽  
Author(s):  
Eizo Nakaza ◽  
Tsunakiyo Iribe ◽  
Muhammad Abdur Rouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Open Channel ◽  
Implicit Method ◽  
Simulation Results ◽  
Moving Particle ◽  
Fixed Structure ◽  
Tsunami Currents

The paper aims to simulate Tsunami currents around moving and fixed structures using the moving-particle semi-implicit method. An open channel with four different sets of structures is employed in the numerical model. The simulation results for the case with one structure indicate that the flow around the moving structure is faster than that around the fixed structure. The flow becomes more complex for cases with additional structures.

scholarly journals An Investigation of Dynamic Responses and Head Injuries of Standing Subway Passengers during Collisions

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yong Peng ◽  
Tuo Xu ◽  
Lin Hou ◽  
Chaojie Fan ◽  
Wei Zhou
Keyword(s):  
Numerical Simulation ◽  
Head Injury ◽  
Head Injuries ◽  
Dynamic Responses ◽  
Passive Safety ◽  
Friction Coefficients ◽  
Safety Design ◽  
Parametric Studies ◽  
Simulation Results ◽  
Set Up

With the development of the subway and the pressing demand of environmentally friendly transportation, more and more people travel by subway. In recent decades, the issues about passenger passive safety on the train have received extensive attention. In this research, the head injury of a standing passenger in the subway is investigated. Three MADYMO models of the different standing passenger postures, defined as baseline scenarios, are numerically set up. HIC15values of passengers with different postures are gained by systematic parametric studies. The injury numerical simulation results of various scenarios with different friction coefficients, collision acceleration, standing angle, horizontal handrail height, and ring handrail height are analyzed. Results show that the horizontal handrail provides better protection in the three different standing passenger postures. Different friction coefficients and the standing angle have great impact on the head injuries of passengers in three different scenarios. The handrail height also has some effects on head injury of passengers with different standing postures, so it is necessary to be considered when designing the interior layout of the subway. This study may provide guidance for the safety design of the subway and some advices for standing subway passengers.

scholarly journals Loads and Response of a Tension Leg Platform Wind Turbine with Non-Rotating Blades: An Experimental Study

2019 ◽  
Vol 7 (3) ◽  
pp. 56 ◽  
Author(s):  
Timothy Murfet ◽  
Nagi Abdussamie
Keyword(s):  
Wind Turbine ◽  
Degrees Of Freedom ◽  
Wind Loading ◽  
Dominant Factor ◽  
Tension Leg Platform ◽  
Rotating Blades ◽  
Motion Responses ◽  
Free Decay ◽  
Response Amplitude Operators ◽  
Decay Tests

This paper describes model testing of a Tension Leg Platform Wind Turbine (TLPWT) with non-rotating blades to better understand its motion and tendon responses when subjected to combined wind and unidirectional regular wave conditions. The TLPWT structure is closely based on the National Renewable Energy Laboratory (NREL) 5 MW concept. Multiple free decay tests were performed to evaluate the natural periods of the model in the key degrees of freedom, whilst Response Amplitude Operators (RAOs) were derived to show the motion and tendon characteristics. The natural periods in surge and pitch motions evaluated from the decay tests had a relatively close agreement to the theoretical values. Overall, the tested TLPWT model exhibited typical motion responses to that of a generalised TLP with significant surge offsets along with stiff heave and pitch motions. The maximum magnitudes for the RAOs of surge motion and all tendons occurred at the longest wave period of 1.23 s (~13.0 s at full-scale) tested in this study. From the attained results, there was evidence that static wind loading on the turbine structure had some impact on the motions and tendon response, particularly in the heave direction, with an average increase of 13.1% in motion amplitude for the tested wind conditions. The wind had a negligible effect on the surge motion and slightly decreased the tendon tensions in all tendons. The results also showed the set-down magnitudes amounting to approximately 2–5% of the offset. Furthermore, the waves are the dominant factor contributing to the set-down of the TLPWT, with a minimal contribution from the static wind loading. The results of this study could be used for calibrating numerical tools such as CFD codes.

The Study of Wake and Array of Double Wind Turbine

2013 ◽  
Vol 448-453 ◽  
pp. 1707-1711
Author(s):  
Rui Yang ◽  
Wei Wei Xia ◽  
Jin Long Li
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Turbulence Intensity ◽  
Fatigue Load ◽  
Wake Effect ◽  
Wake Field ◽  
Aerodynamic Interaction ◽  
Simulation Results ◽  
Effective Use ◽  
Wind Resources

For the effective use of wind resources, and in order to decrease the wake effect on the performance of wind turbine, a numerical simulation has carried out to the aerodynamic interaction between two rotors coaxial arrangement. At last the numerical simulation results are verified by experiment. The results show that downstream turbine makes the upstream diverging wake to be converged when coaxial arrangement, and the output of downstream turbine is affected by upstream wake when the distance is less than 5D.The wake field become more diffused after pass the downstream turbine, the area of diverging wake become larger than the wake of upstream turbine mainly due to the increase of turbulence intensity. The greater fatigue load will impact on the downstream turbine. At last the simulation results are in well agreement with the experimental results.

Study on the Forming Process of the Crossmember in Car Intermediate Floor

2013 ◽  
Vol 442 ◽  
pp. 593-598
Author(s):  
Xue Xia Wang ◽  
Peng Chong Guan ◽  
Hai Peng Li ◽  
Li Hui Wang ◽  
Na Zhang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Process Parameters ◽  
Thickness Distribution ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Simulation Technology ◽  
Forming Process ◽  
Distribution Diagram ◽  
Simulation Results

Flanging and bending forming processes of the crossmember in car intermediate floor are investigated respectively by using numerical simulation technology. The numerical model of the crossmember was established and its press forming effect was simulated to determine the feasible process parameters affecting its manufacturability. Forming limit diagram and thickness distribution diagram are used to evaluate simulation results of different process schemes. And then optimum values of process parameters for flanging and bending are found, which can reduce the tendencies of wrinkling, springback and crackling during the stamping of the product.

Calibration of Hydrodynamic Coefficients for a Semi-Submersible 10 MW Wind Turbine

2018 ◽  
Author(s):  
Marit I. Kvittem ◽  
Petter Andreas Berthelsen ◽  
Lene Eliassen ◽  
Maxime Thys
Keyword(s):  
Numerical Model ◽  
Line Tension ◽  
Offshore Wind ◽  
Scale Model ◽  
Viscous Drag ◽  
Mooring System ◽  
Drag Coefficients ◽  
Damping Coefficients ◽  
Decay Tests ◽  
Drift Forces

Hydrodynamic model tests and numerical simulations may be combined in a complementary manner during the design and qualification of new offshore structures. In the EU H2020 project LIFES50+ (lifes50plus.eu), a model test campaign of floating offshore wind turbines using Real-Time Hybrid Model (ReaTHM) testing techniques was carried out at SINTEF Ocean in fall 2017. The present paper focuses on the process of calibrating a numerical model to the experimental results. The concepts tested in the experimental campaign was a 1:36 scale model of the public version of the 10MW OO-Star Wind Floater semi-submersible offshore wind turbine. A time-domain numerical model was developed based on the as-built scale model. The hull was considered as rigid, while bar elements were used to model the mooring system and tower in a coupled finite element approach. First-order frequency-dependent added mass, potential damping, and excitation forces/moments were evaluated across a range of frequencies using a panel method. Distributed viscous forces on the hull and mooring lines were added to the numerical model according to Morison’s equation. Potential difference-frequency excitation forces were also included by applying Newman’s approximation. The quasi static properties of the mooring system were assessed by comparing the restoring force and maximum line tension with the pull-out test. Drag coefficients for the line segments were estimated by imposing the measured fairlead motion from model tests as forced displacement and comparing the calculated and measured dynamic line tension. The linear and viscous damping coefficients were first estimated based on the decay tests, and the tuned damping coefficients were compared to initial guesses based on the Reynolds and Keulegan-Carpenter number at model scale. The results were then applied in the numerical model, and simulations in extreme irregular waves were compared to the experiments. It was found that second order drift forces proved to be significant, particularly for the severe irregular seastate. These could not be modelled correctly applying the potential drift forces together with quadratic damping matrix tuned to the free decay test. And the model with viscous drag coefficients tuned to decay tests also underestimated the slow drift motions. Thus, new viscous drag coefficients were determined to match the low frequency platform response. To inverstigate the performance of the tuned model, comparisons were made for a moderate seastate and for a simulation with both waves and wind on an operating turbine. In the end, possible further improvements to the modelling were suggested.

The Optimization of Vibration Induced by a V6 Engine Cooling Module

2011 ◽  
Author(s):  
Ji Yang ◽  
Zhiyong Hao ◽  
Ruwei Ge ◽  
Liansheng Wang ◽  
Kang Zheng
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Automotive Industry ◽  
Optimization Design ◽  
Working Condition ◽  
Steering Wheel ◽  
Engine Cooling ◽  
Simulation Results ◽  
Cooling Module ◽  
Specific Working

The engine cooling module consists of condenser, radiator and fan (CRFM), which has long been recognized as a main source of sound and vibration in the automotive industry. As the engine becomes increasingly compact and powerful, customers gradually have higher expectations for automobile NVH performance than ever before. Thus the reduction of noise and vibration induced by CRFM becomes critical, which can greatly influence overall NVH performance. Combined with experimental and numerical methods, this paper focuses on the identification and optimization of steering wheel (SW) vibration induced by CRFM for a vehicle with V6 engine while engine idling. The numerical model established in this paper, based on Matlab and taking chassis vibration into account, can predict and optimize the vibration of CRFM under specific working condition with the help of energy decoupling and Newmark-Beta methodology. The optimization design of CRFM mainly involves the stiffness, position and angle of isolators. The numerical simulation results are validated experimentally, which can help further design of CRFM.

Numerical Simulation on Hydrogen Dispersion in Automobiles due to Storage Cylinder Failure

2011 ◽  
Author(s):  
Yan-Lei Liu ◽  
Jin-Yang Zheng ◽  
Shu-Xin Han ◽  
Yong-Zhi Zhao
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Numerical Model ◽  
Hydrogen Sensor ◽  
High Concentration ◽  
Concentration Region ◽  
Species Transport ◽  
Safety Design ◽  
Simulation Results

A numerical model for dispersion of hydrogen in hydrogen powered automobiles was established basing on finite element method with species transport and reaction module of FLUENT. And corresponding numerical simulations were done in order to analysis the dispersion of hydrogen due to leakage from different position of the storage cylinder on the automobiles. Also, the distribution of the hazard region due to hydrogen dispersion was obtained. The simulation results show that the baffle above the cylinder can accumulate the hydrogen. Therefore, the high concentration region of hydrogen exists near the baffle. The study can provide reference for hydrogen sensor placement and safety design of hydrogen powered automobiles.

Real-Time Hybrid Model Tests of a Braceless Semi-Submersible Wind Turbine: Part III — Calibration of a Numerical Model

2016 ◽  
Author(s):  
Petter Andreas Berthelsen ◽  
Erin E. Bachynski ◽  
Madjid Karimirad ◽  
Maxime Thys
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Simulation Model ◽  
Wind Turbine ◽  
Real Time ◽  
Hybrid Model ◽  
Test Data ◽  
Viscous Drag ◽  
Drag Coefficients ◽  
Aerodynamic Loads

In this paper, a numerical model of a braceless semi-submersible floating wind turbine (FWT) is calibrated against model test data. Experimental data from a 1:30 scaled model tested at MARINTEK’s Ocean Basin in 2015 using real-time hybrid model testing (ReaTHM) is used for the calibration of the time-domain simulation model. In these tests, aerodynamic loads were simulated in real-time and applied to the physical model. The simulation model is based on the as-built model at full scale. The hull and turbine are considered as rigid, while bar elements are used to model the mooring system in a coupled finite element approach. Frequency-dependent added mass, radiation damping, and excitation forces/moments are evaluated using a panel method based on potential theory. Distributed viscous forces on the hull and mooring lines are added to the numerical model applying Morison’s equation. The viscous drag coefficients in Morison’s equation are calibrated against selected test data, including decay tests in calm water and test with irregular waves. Simulations show that the drag coefficients change when waves are present. Aerodynamic loads are included as time varying loads applied directly at the hub based on the actual physical loads from the experiment. This way, uncertainties related to the aerodynamic loads in the calibrations are removed. The calibrated numerical model shows good agreement with experimental data.

Sign in / Sign up

Export Citation Format

Share Document