Horizontal flow in the lower part of the reactor pressure vessel was found responsible for the so-called baffle jets impinging in the direction almost perpendicular to the nuclear fuel rods axes. This flow may generate flow-induced vibrations of the fuel rods that can damage the rods.

As opposed to the flow-induced vibrations in a purely cross-flow situation, as in the case of e.g. heat exchanger tubes, the flow direction in the bottom part of the core barrel is of a combined axial and cross flow nature. One of peculiarities of the baffle jet and fuel rods interaction is the vicinity of the solid walls of the core barrel; also, the velocity profile impacting onto the fuel rods is non-uniform.

The present study aims to further investigate the nature of flow field in the geometry relevant to the baffle jetting in the pressurized water reactors (PWRs). A separate effect study is conducted in order to assess the ability of a number of turbulent models to predict the complicated flow field in the case of baffle jets. Conclusions were drawn for the models’ ability to predict both the time-average and the transient, spectral, characteristics of the flow.

An experimental program PANACHET was employed in CEA, France, for the study of baffle jetting. Flow velocity was measured for the conditions mimicking the flow field in the bottom periphery part of the core barrel. The PANACHET experiments were simulated using the models validated in the separate effects study.

发现在反应堆压力容器下部的水平流动是造成所谓的折流板喷射的原因，该折流板的喷射方向几乎垂直于核燃料棒的轴线。该流动可能产生燃料棒的流动引起的振动，该振动会损坏燃料棒。

与在纯横流情况下的流动引起的振动相反，例如在热交换器管的情况下，芯筒底部中的流动方向具有轴向和横流的组合性质。挡板射流和燃料棒相互作用的特殊性之一是芯筒实心壁的附近。同样，撞击到燃料棒上的速度分布也不均匀。

本研究旨在进一步研究与压水反应堆（PWR）中的挡板喷射有关的几何形状中的流场的性质。为了评估许多湍流模型在挡板射流情况下预测复杂流场的能力，进行了一项单独的效果研究。得出了模型预测流量平均时间和瞬态，频谱特征的能力的结论。

PANACHET实验程序在法国CEA进行，用于挡板喷射的研究。在模拟岩心管底部外围部分中的流场的条件下，测量流速。使用在单独的效应研究中验证的模型对PANACHET实验进行了模拟。