| Current energy of offshore marine renewable energy in China can be exploited up to1.67 million k W,of which the area of Zhoushan Islands along the coast of Zhejiang Province is the most abundant.However,most of the current-intensive waters in Zhoushan are concentrated in Xihoumen Waterway,Guishan Waterway,Guanmen Waterway and Jintang Waterway.These waters have superior geographical position and deep-sea Waterway resources.There are many ships traveling between them,and the navigation density is also high.Therefore,the ship waves generated by the voyage of large ships in the past will affect the stability of floating power generation devices to a certain extent,and even may cause their overturning.Therefore,the CFD method is used to calculate and analyze the influence of ship waves generated under different lateral spacing and navigation speed on the dynamic response of floating power generation unit,which provides practical significance for the design and research of floating power generation unit with horizontal axis turbine.In this thesis,the basic theory of CFD method used in numerical simulation of floating power generation devices is firstly introduced.Then,the energy utilization ratio of the turbine with fixed speed in uniform flow is calculated and analyzed by software STAR-CCM+,which verifies the feasibility of the numerical simulation method.Secondly,the corresponding theory of ship wave and empirical wave height formula of ship wave are introduced.Then,the ship wave generated by relative motion of fixed ship is simulated by numerical simulation software,and the wave states and transverse wave heights under different relative motion speeds are analyzed.The variation rules of the ship wave heights with the increase of transverse interface distance and with the increase of ship speed are obtained.Then,the ship waves generated by ships traveling at different fixed speeds are simulated and calculated.The ship wave states are analyzed according to the range of Fourier number of water depths,and the law that the maximum transverse wave height decreases with the increase of transverse distance is obtained.Finally,the coupling motion between turbine,floating body and navigation ship is simulated and calculated,and the influence of ship waves generated under different lateral spacing and navigation speed on the dynamic response of carrier in floating power plant such as pitch,roll,pitch,axial force,etc.and the hydrodynamic performance such as turbine capacity efficiency and thrust coefficient are analyzed.It is concluded that with the decrease of horizontal spacing at the same speed,the longitudinal roll and thrust coefficient of carrier will decrease with the decrease of horizontal spacing.The sag motion and the x-axis force both fluctuate periodically and the maximum sag and pitch occur at the minimum L transverse distance.The rolling motion amplitude of the carrier increases by 13%,18%,39%and 43% at different speeds.The higher the turbine capacity efficiency,the smaller the thrust coefficient.When the transverse spacing is the same,with the increase of speed,the carrier rolling motion amplitude under different transverse spacing also increases by 42%,18%,9.4%,8.6% and 6.2%;The greater the amplitude of the carrier pitching motion is,especially when the transverse distance is L,the higher the speed from 2.5 m/s to 4 m/s,the 42% increase of the carrier pitching value;Velocity has little effect on carrier pendulum motion.The variation rule of turbine capacity efficiency curves at different speeds is not identical,but the smaller the value of turbine capacity efficiency is.Based on the above data and results,it is concluded that when a sailing ship passes through a floating tidal current power generation device,the sailing speed should be reduced when the lateral spacing is fixed;When the sailing speed is constant,the lateral spacing should be increased to reduce or avoid the impact of ship waves on the power generation device. |
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