熵分析法在盖板式预旋系统分析中的应用

Entropy Analysis of a Cover-Plate Pre-Swirl System

为获得盖板式预旋系统内部流动损失的具体原因并为预旋系统的优化提供依据,基于三维流场数值计算结果,对预旋系统内的熵增以及熵产情况进行了分析。结果表明,进出口参数固定的条件下,忽略系统与外界的传热,熵增为零时可获得最大温降,随着熵增增大,温降逐渐减小;预旋系统各主要部件中供气孔处的熵增的变化量最大,约占到系统整体熵增的37%;预旋系统内湍流耗散产生的熵产比直接耗散产生的熵产大两个数量级,并且出现较大熵产的主要原因是供气孔入口处气流与预旋系统壁面之间的大速度差。

To find out the real reason of the flow losses in a cover-plate pre-swirl system and provide the optimization method,analysis of the entropy increment and entropy generation in a pre-swirl system was carried out based on the results of 3D aerodynamics computation. The results show that the pre-swirl system achieves the largest temperature-reduction only if the entropy increment is zero,with the parameters of the system inlet and outlet fixed and ignoring the heat transfer between the system and the outside. What is more,the temperature-reduction reduces with the entropy increment enlarging. About 37 percent of the system entropy increment,which is the largest part of all,generated by the supply holes. The entropy generation caused by the turbulent dissipation is two orders of magnitude higher than the one caused by the direct dissipation,and the main reason to cause the entropy generation to be large is the large difference of velocity between the flow and the wall in the inlet of supply holes.