ABSTRACT

This chapter on unsteady aerodynamics is included only to emphasize the fact that the angle of attack changes not only with the twist angle θ but also on the flow conditions. In flutter analysis, using an aerodynamic theory for steady flow considers lift and pitching moment as functions of the instantaneous pitch angle, θ, only. However, the angle of attack is not simply equal to θ. Consider the airfoil reference point plunging with velocity ḣ, at least for small angles. The angle of attack including the effect of plunge is given by α   =   θ   +   h ˙ U https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315370613/fdac56c2-d1f9-4161-92d8-34f036aa05f1/content/math_12_1.tif"/>