Rotordynamic Force Coefficients of Gas Seals - An Experimental Approach with Active Magnetic Rotor Excitation

摘要

Gas seals are important components in turbomachines to guarantee high internal efficiency by restricting undesired leakage flows. Moreover, it is important to identify their rotordynamic force coefficients for the use in rotordynamic analyses of turbomachinery. Experimental methods to determine the full set of rotordynamic coefficients require a relative motion between rotor and stator, e.g. using Active Magnetic Bearing (AMB) technology. A unique approach is used in the present test rig, where a single AMB is used as an exciter on a flexible rotor supported by two fluid film bearings. Following an AMB upgrade, a new measurement principle was introduced based on the mechanical impedance method. The present paper describes the upgrade measures on the test rig, the measurement procedure and the parameter identification method along with a calculation scheme for the combined measurement uncertainty. First measurements on a fully partitioned pocket damper seal are performed to validate the new hardware and parameter identification procedure.