Sensitivity analysis for the design and operation of a non-contacting mechanical face seal

Detection and diagnosis of failure in non-contacting mechanical face seals may prevent catastrophes in some critical applications. Seal failure due to face contact may occur because of large relative misalignment between the seal rotor and stator faces. The objective of this work is to study the sensitivity of the relative misalignment to changes in the design and operational parameters of a non-contacting flexibly mounted rotor (FMR) mechanical face seal. These sensitivities can be efficiently exploited to prevent possible contact through proper selection of the seal parameters and working point in both the design and the control stages. Among the design parameters, the seal coning angle is by and large independent of other design requirements and should be properly selected to avoid contact. The operational variables greatly influencing the relative misalignment are the clearance, the bearing fluid pressure and the shaft speed. Where active control is considered, the relative misalignment sensitivity to changes in the control parameters should determine the working point. The sensitivity analysis is demonstrated using the data of an existing seal test rig.