超临界压力水循环系统非线性水动力特性研究

Study on Nonlinear Hydraulic Features of Water Circulation Systems at Supercritical Pressure

建立超临界压力下自然与强制水循环回路的统一水动力模型,结合超临界压力下特殊的物性变化、非线性动量传输与系统耦合特征,采用基于延拓的非线性数值方法,系统比较研究了超临界压力下自然与强制循环水系统的复杂水动力特性,揭示了超临界压力下自然与强制循环系统独特的非单调的流量-加热功率关系及其机制与特点。分析了系统传热特性,并讨论了加热段入口温度、局部阻力对自然和强制循环水动力特性和系统传热的影响规律。

With establishment of a unified hydraulic model for both natural and forced circulation loops, and with considering the unique variation of thermo-physical properties at supercritical pressures, along with the nonlinear momentum transport and system coupling characteristics, this paper, by applying appropriate nonlinear numerical computation based on Continuation concept, presents a systematic comparative study on the complex hydraulic features of both supercritical water systems. Special non-monotonic relationships of mass-flow rate and heating power of both natural and forced circulation, with their mechanisms and features, are revealed and comparatively investigated. Related thermal energy transmission issues of both systems are analyzed as well. Meanwhile, effects of such factors as inlet bulk temperature of heating section, local resistances and/or pump characteristics on system hydraulic and heat transmission features are delivered. Furthermore, characteristics of forced circulation driven by both a real and ideal pump are compared.