多维振荡浮体并联液压缸波浪能捕获动态特性及机理的研究

For the wave energy capture system of parallel hydraulic cylinders with a multi-dimensional oscillation floating body, under irregular waves, the pressure, the flow rate and the output power dynamic performances of parallel hydraulic cylinders and the coupling mechanism, will be investigated. The hydrodynamic model of the multi-dimensional floating body under irregular waves and the piston damping will be established. The motion law of the multi-dimensional floating body and the effect of the floating body parameters, the irregular wave parameters and the damping coefficient of the piston on the motion response of the multi-dimensional floating body will be investigated. The piston dynamic equilibrium model including the hydraulic cylinder output force, the two chambers pressure difference, the friction force and the inertial force, will be set up. The dynamic model among the hydraulic cylinder piston reciprocating movement response, the two chambers volume change due to fluid compressibility, the piston effective work area and the output flow, will be established. Concidering the dynamic performances of accumulators and valves, the system fluid inertia and the pressure loss, the transient model of the pressure and the flow rate in the coupling system of parallel hydraulic cylinders with a multi-dimensional oscillation floating body, will be proposed. Based on the system theory research and experimental simulation, the effect of the significant wave height, the energy period, the floating body diameter, the depth into water, the piston effective working area, the hydraulic cylinder initial volume of two chambers, the accumulator initial pressure and volume, the system fluid inertia and the pressure loss on the output pressure, the flow rate and the output power dynamic performances of parallel hydraulic cylinders and the coupling mechanism, will be investigated. The research results will provide the theory basis for the design and development of the wave energy capture system using parallel hydraulic cylinders with a multi-dimensional oscillation floating body.

本项目针对多维振荡浮体并联液压缸波浪能捕获系统，研究不规则波条件下多维浮体作用并联液压缸输出压力、流量和功率动态特性及耦合机理。建立不规则波条件下受活塞阻尼的多维浮体的水动力模型，研究多维浮体运动响应规律及浮体参数、不规则波参数和活塞阻尼系数对浮体运动响应规律的影响；建立并联液压缸输出动力与两腔压差、摩擦力、惯性力的平衡模型；建立并联液压缸输出流量与活塞往复运动响应、流体压缩的体积变化、液压缸参数的模型；考虑蓄能器和阀的动态特性、流体惯性及压力损失，提出多维浮体并联液压缸耦合压力和流量瞬变系统模型。通过系统理论研究与实验模拟相结合，揭示有效波高、能量周期、浮体直径、入水深度、活塞有效工作面积、液压缸两腔初始体积、蓄能器初始压力和体积、系统流体惯性和压力损失对并联液压缸输出压力、流量和功率动态特性的影响规律及耦合机理。研究成果为多维振荡浮体并联液压缸波浪能捕获系统的设计和开发提供理论依据。

面对能源需求及环境污染，各国竞相研发海洋波浪能发电技术。经历了几代技术的发展，如何提高波浪能捕获效率成为下一代技术研发的关键，本项目提出了多维振荡浮体并联液压缸波浪能捕获，建立不规则波作用输出为线性阻尼的多维浮体的水动力模型，研究多维浮体运动响应及浮体参数、不规则波参数和输出阻尼系数对浮体运动响应的影响规律。建立液压缸动力平衡和弹性压缩模型，蓄能器压力瞬变模型及系统的动力传输模型，研究了不规则波特征参数、浮体设计参数和液压系统设计参数对系统输出压力和流量、功率捕获和输出动态特性的影响规律。结果表明锥体垂荡和纵摇捕获的功率随直径的增大而增大，纵荡捕获功率随入水深度在一定范围增加而增大，纵摇捕获功率随重心降低而增大。圆柱垂荡和纵荡捕获功率随直径增大而增大，直径和入水深度对圆柱纵摇捕获功率影响较小。有效波高为1.75m，能量周期为5.5s，直径8米，入水深度4米，重心-1m的锥体捕获功率为38.95kW，捕获效率为60.51%。中国南海海域六个观测点的捕获效率为38.98%-47.95%。液压缸输出力呈不规则矩形波变化，经过蓄能稳压后马达输出功率较平稳。液压缸活塞工作面积需要匹配马达排量可捕获最佳能量。随高压蓄能器初始压力增大，捕获功率、捕获效率和马达输出功率呈下降趋势。随高压蓄能器初始体积增大，捕获功率和捕获效率逐渐减小趋于平稳，马达输出功率和液压转化效率呈下降趋势。随有效波高增大，液压缸平均输出力、捕获功率、高压蓄能器压力、液压马达转速及输出功率均增大。直径为6米的圆柱，有效波高为4m，能量周期为5.5s的海况下，垂荡方向捕获功率为62.44kW，马达输出功率为47.52kW，液压转换效率为76%。不同海况下液压转换效率为74%-80%。南海15个观测点中全年最大能够捕获能量106.82MWh。本研究对于我国海域波浪能装置的设计提供了理论依据，具有潜在的工程应用价值。