Abstract
Mechanical seals are commonly used in rotating machinery to contain liquid leakage past a rotating shaft. Pumps vibration often exhibit both synchronous and sub-synchronous whirling, which may lead to premature failure of mechanical seals. A test rig was developed to simulate a running pump environment for the mechanical seal. The controlled-motion test rig comprises a flexibly-mounted-rotor connected to a pair of electrohydraulic shakers. This configuration allows imposing whirl orbits to a flexibly-mounted-rotor (FMR) mechanical seal at any prescribed frequency independent of rotor speed. A 6-axis load cell provides direct measurements of the reaction forces at the mechanical seal stationary component. Five Eddy current sensors and capacity probes track the 5 DOFs of the mechanical seal dynamic face. The flow loop is a modified plan 54 with an external pump capable of delivering 32 lpm at 14 bar using VG 2 mineral oil, and an external heat exchanger to regulate oil temperature. Tests were performed on a 3-inch (76.2 mm) FMR seal. Input rotor whirl vibration was increased to 10 mils pk-pk (254 microns), while cooling flow (VG2 mineral oil) was set to 8 lpm and pressure was varied from 1.7–6.9 lpm. The measurements include steady state values of temperature, power loss, clearance and leakage; and dynamic measurements of seal face wobble, wobble-imposed torque, relative lateral movement and fluid film shear.