Analytical Investigations on the Contact Force Between Bristle Packs and Shaft Surface of Brush Seals

Abstract

The contact force between single bristle and shaft surface, as well as full bristle pack and rotor surface were analytically investigated. The contact force model between single bristle and shaft surface was established using cantilever beam theory. The eccentric whirling motion was taken into account in the present numerical model. The numerical method for the normal contact force and tangential friction force between the seal and shaft surface was derived. The effects of the eccentric whirling motion, bristle lay angle and bristle interference on the contact force of brush seals were conducted using the developed analytical model and method. The variation characteristics of the normal contact force and tangential frictional force torque between single bristle and rotor surface along the circumferential direction with different bristle lay angle, eccentric whirling motion and bristle interference was illustrated and analyzed. The numerical analysis results of the contact force between full bristle pack and shaft surface show that the contact force decreases at first and increases later with increasing the bristle lay angle at the fixed bristle interference and eccentric whirling motion. The contact force obtains the minimum when the bristle lay angle equals to 54° at the eccentric whirling motion 0.5mm and bristle pack interference 1.5mm.