In the present work, the CFD-based method coupled with the dynamic overset grid technique is applied to investigate the hydrodynamic performance of the fully appended ONR tumblehome ship model under self-propulsion co...In the present work, the CFD-based method coupled with the dynamic overset grid technique is applied to investigate the hydrodynamic performance of the fully appended ONR tumblehome ship model under self-propulsion condition in head waves. All the computations are carried out by our in-house CFD solver naoe-FOAM-SJTU and the overset grid module is used to update the ship motions with rotating propellers while a self-developed 3D wave tank module is applied to generate desired wave environment. The ship model is advancing at its model point obtained with previous CFD results in calm water and the simulation is according to the bench- mark case from the Tokyo 2015 CFD Workshop in ship hydrodynamics. The predicted results, i.e. ship motions and instantaneous advancing speeds are presented and compared with the availa- ble experimental data. Propulsion coefficients, Kr and KQ, as well as detailed information of the flow field are also given to explain the hydrodynamic performance during the self-propulsion in waves. Good agreements are achieved which indicate that the present approach is applicable for the direct simulation of self-propulsion in waves.展开更多
In this paper, numerical simulations of FPSO ship motion coupled with LNG tank sloshing with low-filling ratios are conducted. The fully coupled problem is addressed with our own unsteady RANS solver: naoe-FOAM-SJTU d...In this paper, numerical simulations of FPSO ship motion coupled with LNG tank sloshing with low-filling ratios are conducted. The fully coupled problem is addressed with our own unsteady RANS solver: naoe-FOAM-SJTU developed based on the open source tool librar- ies of OpenFOAM. The internal tank sloshing and external wave flow are solved simultaneously. The FPSO model includes 2 LNG tanks. For the ship 3-DOFs are released in the regular beam waves. The filling ratios of the 2 tanks are 20% - 20%, lower than the external free surface. This kind of low-filling condition reduces ship roll motion significantly, and produces complex free surface shapes in tanks. 4 different incident wave frequencies are considered in the simulation in comparison with the existing experimental data. The comparison shows that the numerical re- sults are in good agreement with the experimental data, proving the reliability of the proposed method. The filling conditions with large wave amplitudes are studied further, and due to the coupling effect, violent sloshing occurs in tanks and impulsive pressure forms on bulkhead.展开更多
In this paper, 2 detached-eddy simulation (DES) approaches, namely SST-DES and SST-DDES are implemented, integrated in to the naoe-FOAM-SJTU solver which is developed based on the open source platform OpenFOAM. Flow p...In this paper, 2 detached-eddy simulation (DES) approaches, namely SST-DES and SST-DDES are implemented, integrated in to the naoe-FOAM-SJTU solver which is developed based on the open source platform OpenFOAM. Flow past 2 cylinders in tandem arrangement is selected as the benchmark case for the validation of the SST-DES and SST-DDES approaches. The experiment was previously conducted in 2 different wind tunnels at the NASA Langley Re- search Center. Time-averaged flow fields and some quantities of computational results are com- pared with experiments. In addition, the 3D instantaneous flow structures are also given and discussed. It is shown that the current implementation of SST-DES and SST-DDES is able to re- solve some characteristics for massively separated complex turbulent flows.展开更多
文摘电池组中单体间存在的不一致性是电池状态估计问题中的一大难点。针对串联锂离子电池组,提出了一种基于强跟踪滤波器（strong tracking filter,STF）与LevenbergMarquardt（LM）算法相结合的电池组不一致性辨识与状态估计的新方法。首先针对＂参考单体＂给出了一阶等效电路模型与开路电压–荷电状态（state of charge,SOC）特性关系曲线,通过STF算法得到其状态估计与参数估计;其次建立不同单体的＂电压相似函数＂,并引入LM算法对SOC、极化电压、欧姆内阻3种不一致因素进行辨识;最后对2组5个LiFePO4单体串联的电池组在不同的工况下进行了实验验证。结果表明,所提方法对各单体的状态与内阻估计误差在合理的范围内,对电池组不一致性辨识与状态估计具有良好的效果。
文摘In the present work, the CFD-based method coupled with the dynamic overset grid technique is applied to investigate the hydrodynamic performance of the fully appended ONR tumblehome ship model under self-propulsion condition in head waves. All the computations are carried out by our in-house CFD solver naoe-FOAM-SJTU and the overset grid module is used to update the ship motions with rotating propellers while a self-developed 3D wave tank module is applied to generate desired wave environment. The ship model is advancing at its model point obtained with previous CFD results in calm water and the simulation is according to the bench- mark case from the Tokyo 2015 CFD Workshop in ship hydrodynamics. The predicted results, i.e. ship motions and instantaneous advancing speeds are presented and compared with the availa- ble experimental data. Propulsion coefficients, Kr and KQ, as well as detailed information of the flow field are also given to explain the hydrodynamic performance during the self-propulsion in waves. Good agreements are achieved which indicate that the present approach is applicable for the direct simulation of self-propulsion in waves.
文摘In this paper, numerical simulations of FPSO ship motion coupled with LNG tank sloshing with low-filling ratios are conducted. The fully coupled problem is addressed with our own unsteady RANS solver: naoe-FOAM-SJTU developed based on the open source tool librar- ies of OpenFOAM. The internal tank sloshing and external wave flow are solved simultaneously. The FPSO model includes 2 LNG tanks. For the ship 3-DOFs are released in the regular beam waves. The filling ratios of the 2 tanks are 20% - 20%, lower than the external free surface. This kind of low-filling condition reduces ship roll motion significantly, and produces complex free surface shapes in tanks. 4 different incident wave frequencies are considered in the simulation in comparison with the existing experimental data. The comparison shows that the numerical re- sults are in good agreement with the experimental data, proving the reliability of the proposed method. The filling conditions with large wave amplitudes are studied further, and due to the coupling effect, violent sloshing occurs in tanks and impulsive pressure forms on bulkhead.
文摘In this paper, 2 detached-eddy simulation (DES) approaches, namely SST-DES and SST-DDES are implemented, integrated in to the naoe-FOAM-SJTU solver which is developed based on the open source platform OpenFOAM. Flow past 2 cylinders in tandem arrangement is selected as the benchmark case for the validation of the SST-DES and SST-DDES approaches. The experiment was previously conducted in 2 different wind tunnels at the NASA Langley Re- search Center. Time-averaged flow fields and some quantities of computational results are com- pared with experiments. In addition, the 3D instantaneous flow structures are also given and discussed. It is shown that the current implementation of SST-DES and SST-DDES is able to re- solve some characteristics for massively separated complex turbulent flows.
