Indo - UK: Premature, Oscillation-Induced Critical Heat Flux ("Premature OICHF")

水是核反应堆的极好冷却剂，但蒸汽是一种很差的冷却剂。有信心地预测，但没有过度保守的能力，水冷却将变成蒸汽冷却的点是绝对重要的。这种转变发生时的热传递速率被称为“临界热通量”（CHF）。（然后确保反应堆运行条件远离它们）是水冷反应堆热工水力设计的很大一部分。有一些，不寻常的，核反应堆内的流动可能变得不稳定和周期性，流速随着时间的推移而上升和下降。在这种情况下，预测临界热通量并不令人惊讶地变得相当复杂和困难。本项目试图建立一个计算机模型，该模型将预测在存在循环流的情况下临界热通量何时出现。本计画的第二部份是进行实验，将一个实验段暴露于一个循环流中，观察临界热通量的出现与否。我们开发的模型将根据这些测量结果进行测试和改进。一个经过验证的，通用的工具，用于预测振荡流条件下的临界热通量将是一个有用的额外能力，可供反应堆设计师和安全分析师。

Water is an excellent coolant for nuclear reactors, but steam is a very poor one. The ability to predict with confidence, but without excessive conservatism, the point at which cooling by water will turn into cooling by just steam is absolutely vital. The the rate of transfer of heat at which this transition occurs is known as the "critical heat flux" (CHF).Predicting the circumstances under which CHF would occur (and then making sure that reactor operating conditions stay well away from them) is a very large part of the thermal hydraulic design of water cooled reactors.There are some, unusual, circumstances in which the flows inside a nuclear reactor can become unsteady and cyclical, with flow-rates rising and falling with time. Under the circumstances, predicting the critical heat flux not surprisingly becomes rather more complicated and difficult.This project is attempting to build a computer model which will predict when critical heat flux occurs in the presence of cyclical flows. The second strand of this project is to conduct experiments in which a test section is exposed to a cyclical flow, and the occurrence or not of critical heat flux is observed. The model we develop will then be tested and refined against these measurements.A validated, general-purpose tool for predicting critical heat flux under conditions of oscillatory flow will be a useful additional capability available to reactor designers and safety analysts.