Research on an Improved Method for Galloping Stability Analysis Considering Large Angles of Attack

In view of the deficiency of the quasi-steady galloping critical wind speed calculation method based on the classical Den Hartog criterion, this paper proposes a quasi-steady galloping stability analysis method that considers the wind attack angle criterion (dC(V)/d alpha) through theoretical analysis. Firstly, the tri-component force coefficients of a square-section model were measured through wind tunnel tests, and the galloping force coefficients calculated with three different galloping criteria (the dC(V)/d alpha criterion, Den Hartog criterion, and Xie criterion) were compared and analyzed. Secondly, to further verify the reliability and applicability of the criteria proposed in this study, wind tunnel tests and numerical simulations were conducted on an H-shaped section. The verification results of the H-shaped section showed that under the action of the incoming flow at a large angle of attack of 70 degrees, the maximum error of the classic Den Hartog criterion could reach about 44%. This study used the dC(V)/d alpha criterion while considering the large angle of attack of the incoming flow, and its calculation error could be controlled within 10%. At the same time, the numerical simulation showed that there was serious aerodynamic instability in this section under the critical wind speed. A pair of periodic vortex structures were formed in the wake region of the H-shaped section, resulting in constant generation and separation phenomena, which induced structural instability.