功耗率最小原理在流体管网计算中的运用

Use of minimum power dissipation rule in flow calculation of fluid pipe-net

流体管网一般采用节点质量守恒和环路压力平衡的原则,结合伯努利方程,求解多元方程组进行计算。根据非平衡态热力学原理定义管路中的功耗率函数后,以质量守恒和能量守恒原理为约束条件的最小能耗率原理同样可以运用于流体管网的分析计算,分析过程中证明了压力平衡的原则是功耗率最小原理的自然结果。同时从分析过程可以看出,功耗率最小原理为大型复杂管网的程序化计算提供了方便,并且适用于瞬态分析。

Conventional calculation of flow in fluid pipe-net is based on the rules of mass conservation, pressure balance in the closed net and the Berluri equation.After definition of energy dissipation rate function according to the Unbalance Thermodynamics Theory,the minimum power dissipation rule is used for the calculation under the mass and energy conservation rules.The results show that the pressure balance is in fact one conclusion of the minimum power dissipation rule in fluid pipe-net.The analyzing process shows the rule of energy minimum dissipation rate can give convenience in the calculation of large or complex fluid pipe-net,and can be used in transient condition of the flow in pipe-net.