Simulation of entropy generation during the evolution of rotating stall in a two-stage variable-pitch axial fan

Abstract

Rotating stall is a common instability phenomenon that occurs in turbomachinery. Rotating stall 3D instability can be characterized as one or more stall cells rotating at a fraction of rotor velocity. In this article, the ANSYS Fluent software was used to numerically simulate entropy generation. The relative velocity of the monitoring points in the rotor is discussed, and the type of stall inception is a spike. In addition, five typical conditions that affect the evolution of rotating stalls are presented and discussed with respect to characterizing entropy generation in a two-stage variable-pitch axial fan. The results reveal that entropy generation significantly improves after the stall phenomenon appears. Because rotating stall first occurs in the second rotor, its entropy production is higher than that of the first rotor over the entire evolution period. The high entropy generation region moves in the circumferential and radial directions of the first and second rotors during the evolution of rotating stall.