熵方程在瞬态空气系统流动方向判断中的应用

将非平衡态的熵方程应用于空气系统的求解中,推导了管道元件和节流元件内的熵产变化率的表达式,并通过熵产的非负性来判断流体的流动方向。结合模块化的建模思想,建立了瞬态空气系统流体网络法仿真程序。使用Shock-tube 模型与双腔模型进行验证。仿真结果与实验结果基本吻合，表明利用非平衡态的熵产能够准确判断瞬态空气系统中的流动方向，克服了总压判断的局限性，加速了空气系统的收敛。 

Application of entropy equation in the judgement of flow direction in transient air system

The entropy equation of the non equilibrium state was applied to the solution of air system. An expression of the change rate of entropy production in the pipe element and throttle element were derived. And the flow direction of the fluid was judged by the non negativity of the entropy production. Combined with the think of modular modeling, the fluid network simulation program of the transient air system was established. The Shock tube model and double cavity model were used to verify the algorithm accuracy. The simulation results are in good agreement with the experimental results, which show that the non equilibrium entropy production can accurately determine the flow direction in the transient air system, overcome the limitation of the total pressure judgment and accelerate the convergence of the air system.