SCWR - Characterization and Modelling of Heat Transfer and Pressure Loss in Vertical-Flow Bundle Subassemblies

建议的研究包括一个系统的研究传热，压力损失和湍流混合特性的超临界水反应堆（SCWR）的燃料束通过实验补充直接数值模拟，并最终在开发的半分析预测模型，可以纳入SCWR设计工具。实验将在两个现有的测试装置上进行，这些测试装置被配置用于在超临界压力和温度下使用R134a和水进行热工水力研究，重点是上流和下流管束子组件配置。将对稳态和瞬态条件进行测试。互补的直接数值模拟的目的是阐明占主导地位的物理机制负责的独特的动量和传热特性时，在通道流动的工作流体处于超临界状态。具体而言，计算工作的重点将是湍流的相干流结构和这些结构的敏感性以及它们对伪临界点附近的工作流体的热力学状态的相互作用。

The proposed research consists of a systematic study of the heat-transfer, pressure-loss and turbulence mixing characteristics of Supercritical Water Reactor (SCWR) fuel-bundle subassemblies through experimentation complemented by direct numerical simulations, and culminates in the development of semi-analytical prediction models that can be incorporated in SCWR design tools. The experiments are to be performed on two existing test setups configured for thermal-hydraulic studies using R134a and water at supercritical pressure and temperature, and the focus is to be on upward-flow and downward-flow bundle subassembly configurations. Tests will be performed for both steady and transient conditions. The complementary direct numerical simulations are intended to shed light on the dominant physical mechanisms responsible for the unique momentum and heat transfer characteristics observed in channel flows when the working fluid is at a supercritical state. Specifically, the focus of the computational effort will be on the coherent flow structures of turbulence and sensitivity of these structures and their mutual interactions to the thermodynamic state of the working fluid near the pseudo-critical point.