Stability of rotation of a vane in a flow

The results of investigation of stability of permanent rotation of a four-blade vane on a weightless rod in a flow of homogeneous medium are discussed. The rod rotates about a fixed point where a spherical joint is situated. The vane rotates about the second joint fixed at the other end of the rod. Stability of permanent rotation of the vane is studied when the rod coincides with the dynamic symmetry axis of the vane. The results are compared with the one-joint case. It is shown that increasing the number of degrees of freedom leads to “diminishing” the stability domain projection onto the corresponding subspace of parameters.