【作者】 郭春立；

【导师】 阎祥安； 张大卫；

【作者基本信息】 天津大学 ， 机械电子工程， 2009， 博士

【摘要】 本文针对水轮机筒阀关闭过程中的水力特性和多液压缸接力器协同驱动系统的特点,在天津市科技支撑项目、天津大学青年教师培养基金项目和天津市天发重型水电设备制造有限公司的共同资助下,重点对筒阀的关闭过程进行了CFD(Computational Fluid Dynamics)数值模拟,并针对筒阀多液压缸协同控制系统的特点进行了数学建模分析和控制策略研究。论文主要研究内容和成果如下:(1)在目前普遍运用模型试验方法研究筒阀性能的基础上,运用CFD方法中的RNG k-ε湍流模型、混合物多相流模型、动网格和滑移网格技术,以云南红河南沙水电站水轮机筒阀为研究模型,对筒阀动水、静水关闭过程进行了三维数值模拟,较真实地模拟了水轮机发生飞逸时筒阀关闭的水力特性。(2)利用数值模拟的结果得出了筒阀表面压力的分布状况、轴向和周向液动力变化趋势、流量和流态特征以及水力效率和水头损失,给出了不同行程处筒阀附近引流部件的流场特征,根据轴向力载荷和对水轮机转轮工作状态的影响提出了优化的筒阀的关闭方式。(3)通过计算得出了混流式水轮机尾水管涡带的流场特征和筒阀附近压力脉动的幅频特征,结合尾水管涡带的流场特征解释了筒阀附近压力脉动的形成机理,同时给出了空化系数和转轮出口流场等因素对筒阀稳定性的影响。(4)综合CFD方法得到的筒阀倾覆力矩、轴向力计算结果得出了筒阀六缸协同控制系统数学模型。根据水轮机筒阀多缸协同控制系统对同步与速度控制性能的要求,采用定量反馈控制理论(QFT)设计了系统的控制器,满足了系统的跟踪性能、鲁棒稳定性和输入扰动抑制性能指标,有效地解决了实际液压系统不确定性、非线性和时变性等因素影响。(5)系统仿真结果说明,QFT控制策略可以有效地解决多液压缸接力器驱动情况下的同步与速度问题,避免系统的非线性和参数不确定性产生的不利影响。(6)经云南红河南沙水电站的实际应用,验证了筒阀系统同步性能的可靠性和数值模拟得出的液压缸接力器力载荷结果。更多还原

【Abstract】 With the purpose of studying hydraulic characteristics of ring gate in shut-down water process and multi-cylinder synchronous system, this dissertation mainly deals with numerical simulation of shut-down process with use of computational fluid dynamics, mathematic modeling on synchronous system along with stability control strategy. The main contents and contributions of this dissertation are listed as follows.(a) Dynamic mesh, RNG k-εmodel, multi-phase model and sliding mesh are used in order to perform three dimensional unsteady numerical simulation of ring gate in Nansha Hydropower Station on Honghe River during shut-down water process, which is different from the widely used model experiments and simulates hydraulic characteristics to avoid runaway phenomenon.(b) Hydraulic characteristics such as pressure distribution, the axial hydrodynamic force, the flow rate, the efficiency and hydraulic loss are analyzed. And the characteristics of flow field near ring gate are also presented. In addition, optimized closing motion style is provided according to axial hydrodynamic force and working state of Francis turbine.(c) The characteristics of flow field in draft tube vortex tape are presented along with relationship between amplitude and frequency about the pressure fluctuation near ring gate. And the reason for pressure fluctuation is given according to the characteristics of flow field in draft tube. In addition the influence of cavitation coefficient and outlet flow field on stability of ring gate is provided.(d) Mathematic model of six-cylinder synchorous control system is obtained with overturning momentum and axial force model by means of CFD. The controller with use of QFT satisfies the need for trace ablity, robust stability and input disturbance restraint ability, which gets over the uncertain, non-linear and time-variable factors.(e) It shows that QFT control strategy can solve the problem of synchronization and velocity, which keeps from unfavorable influence of non-linear and uncertain factors.(f) The reliability of synchorous system and axial force of cylinders by numerical simulation are verified by engineering applications of Nansha Hydropower Station on Honghe River.更多还原