Flutter derivatives of a flat plate section and analysis of flutter instability at various wind angles of attack

摘要

Flutter derivatives of a flat plate section with side ratio of 40 were obtained under various wind angles of attack via forced vibration test, based on which flutter instability was further analyzed in detail. Accuracy of the experimental setup was firstly verified by comparison of flutter derivatives between experimental and theoretical results at 0 degrees wind angle of attack. Detail discussions on distributions of flutter derivatives under various wind angles of attack were conducted and potential influence of changing flutter derivatives on flutter performance was analyzed. It reveals the dramatic changing of A*(2), with changing of wind angle of attack. The most significant change in the flutter derivatives is the sign change of A*(2) from negative to positive at a 5.5 degrees wind angle of attack. The accuracy of tested flutter derivatives was verified by comparing calculated critical wind speed with those from wind tunnel test. Flutter instability characteristics at various wind angles of attack were discussed, which can aid understanding on flutter behavior of flat plate section by considering effect of large wind angles of attack. Finally, characteristic of flutter index was discussed to demonstrate the flutter performance varying with reduced speed at various wind angles of attack. It remains stable when reduced wind speed less than 6 at wind angle of attack less than 3 degrees, which can be directly used for predicting critical flutter speed of flat plate.