直驱式波能装置振动及转换效率分析

波浪能利用装置一般是利用振动来获取波浪能量,如鸭式装置、点吸收式装置。点吸收技术是世界上目前研究得比较热门的一类波浪能利用技术,漂浮直驱式波能装置是点吸收技术的一种。文章首先通过物理过程分析,把由双圆柱浮体构成的漂浮直驱式波浪能装置当成一个双自由度振动系统,建立系统振动方程;然后,运用势流理论求解由双圆柱浮体的垂荡辐射问题和绕射问题,求解出振动分析所需要的水动力学参数。考虑波浪能装置通过粘性阻尼吸收波浪能,利用求得的水动力学参数,设定的外部阻尼和弹簧弹性系数,可求解出此情况下水面浮体和水下浮体的相对运动幅值,进而求得装置的转换效率。给定模型尺寸参数,在一些确定的外部阻尼值和弹簧弹性系数点,分别通过变化外部阻尼和弹簧弹性系数,分析装置的振动特性以及转换效率的变化,从而在不同波况下选择适合装置的外部阻尼系数和弹簧弹性系数。     

顺应新潮流 把握新趋势简

Mean wind force coefficients of nacelles are investigated by a wind tunnel test and are compared with those in current codes, such as the Germanischer Lloyd Guideline 2010 (GL2010) and Eurocode, in order to clarify the effects of the ground, presence of a hub, turbulence in the incident flow and nacelle length on these coefficients. Formulas for the mean wind force coefficients are proposed as a function of yaw angles. It is found that mean wind force coefficients of wind turbine nacelles specified in GL2010 are underestimated in comparison with those obtained by wind tunnel tests. Pressure measurements of a nacelle are also conducted. Notably, the mean pressure coefficients for design load case 6.2 (DLC6.2) are significantly larger than those for design load case 6.1 (DLC6.1) in IEC61400‐1. Maximum and minimum mean pressure coefficients are proposed for the DLC6.1 and DLC6.2 by the wind tunnel test, which are similar to those in Eurocode and are larger than those proposed in GL2010. Copyright © 2012 John Wiley & Sons, Ltd.