Experimental Investigations of Rotor Whirl Excitation Forces Induced by Labyrinth Seal Flow

The labyrinth seal flow-induced forces have been identified as one of the causes of rotordynamic instabilities in the recent literature. The eccentricity of the rotor center relative to the seal center introduces asymmetry in the seal clearance flow causing circumferential variation of the pressure in seal cavities. Experimentally-measured seal cavity pressure distributions for different rotor eccentricities are presented in this paper. Resultant seal forces obtained by integrating the circumferential pressures over the rotor surface are presented as a function of rotor eccentricity. The experimental results are also used to validate the analytically predicted seal pressure distributions and forces.