Experimental study on mechanical performance of expansion turbine with aerodynamic bearings

The mechanical performance of a turbo-expander with aerodynamic self-acting gas bearings was experimentally studied. The compliant foil journal bearing with elastic support and spiral groove thrust bearing were applied to a 150 m³/h normal-air turbo-expander with the nominal working speed of 106400 r/min, the journal diameter is 25.0 mm and the rotor mass is 891 g. They can support the rotor steadily revolving at 12.16 × 10⁴ r/min, which was overspeed by 14%. The experimental results indicate that the loss of thrust load is the main reason bringing on the destroy of rotor-bearing stability. The characteristic of axial clearance and its outside influencing factors are discussed. It can be confirmed from the experimental study that the application of this combination of two types of self-acting gas bearings to the cryogenic turbo-expander is feasible.