A revised model for rubbing between rotating blade and elastic casing

• A revised blade-casing rubbing model is presented.
• A test rig for blade-casing rubbing is established.
• The model validity is verified by experiment.
• Effects of three types of blade on normal rubbing force are analyzed.
• Effects of two types of casing on normal rubbing force are analyzed.

In this paper, a new rubbing model between a rotating blade and elastic casing is derived based on the law of conservation of energy. In this model, the bending deflection of blade and the casing deformation during rubbing are taken into account. Based on this model, the influences of the penetration depth, casing stiffness, friction coefficient, blade physical dimensions (thickness, width and length) on the quasi-static normal rubbing forces are analyzed. Moreover, the effects of blade types (thin, thick and tapered blades), casing stiffnesses (aluminum and steel casings), penetration depths and rotating speeds on the normal rubbing forces are also evaluated by simulation and experiment. Moreover, by establishing the dynamic model of the blade and casing, the dynamic normal rubbing forces are also calculated under the blade-casing rubbing. The results show that the rubbing model has satisfactory accuracy by comparing simulation with experiment; the linear or nonlinear characteristic of normal rubbing force depends on the stiffnesses of the blade and the casing; the dynamic normal rubbing force is less than the quasi-static normal rubbing force, and both have the same change trend.