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为模拟核电厂严重事故下安全壳内水蒸气的壁面冷凝现象,在安全壳氢气分析专用计算流体力学(CFD)程序HYDRAGON中加入壁面冷凝模型。该模型根据传质传热类比原理建立,为Navier-Stokes方程组提供相关的边界条件、质量源项和能量源项。为验证程序和模型的有效性,从公开发表的文献中选取TOSQAN实验作为测试算例,并与模拟结果进行比较。研究显示,该冷凝模型的计算结果与实验数据吻合较好。对计算结果的分析,也说明了壁面冷凝现象所产生的作用:一方面,壁面冷凝减少了体系中的水蒸气含量,抑制了安全壳内压力的升高,同时也使不可凝气体(如氢气)的比例上升;另一方面,因冷凝现象而引起的壁面附近对流换热也加强了体系内气体的流动,这将不利于在安全壳顶部形成稳定的氢气分层,从而降低氢气爆炸风险。
In order to simulate the surface condensation of water vapor in the containment under the serious accident of a nuclear power plant, a wall condensation model was added to HYDRAGON, a special computational fluid dynamics (CFD) program for containment hydrogen analysis. The model is based on the principle of mass transfer heat transfer and provides the relevant boundary conditions, mass source terms and energy source terms for the Navier-Stokes equations. To verify the validity of the program and the model, TOSQAN experiments were selected from the published literature as test cases and compared with the simulation results. The study shows that the calculated results of the condensation model are in good agreement with the experimental data. The analysis of the calculation results also shows the effect of wall condensation: on the one hand, wall condensation reduces the content of water vapor in the system and suppresses the increase of pressure in the containment, meanwhile, it also makes non-condensable gases such as hydrogen ). On the other hand, the convective heat transfer near the wall caused by condensation also enhances the gas flow in the system, which will not be conducive to the formation of stable hydrogen stratification at the top of the containment, thus reducing the hydrogen explosion risk.