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

本文提出的研究包括通过实验和直接数值模拟对超临界水反应堆（SCWR）燃料束组件的传热、压力损失和湍流混合特性进行系统研究，并最终开发可纳入SCWR设计工具的半解析预测模型。实验将在两个现有的热水力研究测试装置上进行，使用R134a和超临界压力和温度下的水，重点是向上流动和向下流动的束组件配置。测试将在稳定和瞬态条件下进行。互补的直接数值模拟旨在阐明当工作流体处于超临界状态时，在通道流动中观察到的独特动量和传热特性的主要物理机制。具体来说，计算工作的重点将放在湍流的相干流结构和这些结构及其相互作用对伪临界点附近工作流体热力学状态的敏感性上。

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.