论文部分内容阅读
物质气液临界点附近热物理性质发生剧烈变化,会出现一种对热力学平衡有显著加速作用的热声活塞效应。而在长时间尺度上,因重力作用而产生的Rayleigh-Bénard对流在活塞效应的影响下,其表现出来的物理特性与普通流体相比存在较大的差异。我们通过SIMPLE方法对超临界氮在不同临界距离下的自然对流发生过程进行数值模拟,结果显示当流体热力学状态接近临界点时,对流作用的发生取决于边界层内热羽流的形成,并且具有明显的湍流特征,而随着离开临界点的距离加大,流场的形成逐渐过渡到一般可压缩流体的情形。
The thermophysical properties change sharply near the critical point of the material gas-liquid, and a thermoacoustic piston effect will appear that accelerates the thermodynamic equilibrium significantly. In the long time scale, the Rayleigh-Bénard convection due to gravity has a great difference from the normal fluid under the influence of piston effect. The SIMPLE method is used to simulate the natural convection of supercritical nitrogen at different critical distances. The results show that the convection effect depends on the formation of thermal plume in the boundary layer when the thermodynamic state of the fluid is close to the critical point, Turbulent characteristics of the turbulent flow, and as the distance from the critical point increases, the flow field gradually transition to the general case of compressible fluid.