Performance of thrust airfoil bearing for oil-free turbomachinery

Abstract

Introduction During operation of any turbomachinery, the pressure distribution on rotor parts, i.e., impellers, causes an occurrence of radial and thrust forces. These forces must be transferred by the bearings to the machine casing. One of the most promising bearing types that can be applied in modern high-speed turbomachinery is the airfoil bearings. They have low losses, they can operate at relative high rotational speed, and they usually are lubricated with machine working medium. On the other hand, they have relative low bearing load capacity (DellaCorte and Valco in Tribol Trans 43:795-801, 2000 ; Radil and DellaCorte in Tribol Trans 53, 771-778, 2010 ). This problem especially concerns the airfoil thrust bearing. Objective The article describes the performance and operational properties of a thrust airfoil bearing on the test stand. Method The test stand consisted of vertical axis electric motor with thrust plate attached to the shaft. The test covered a wide range of loads and rotational speeds. At these various conditions, the bearing frictional torque was measured. Indirectly, the power loses were calculated depending on the applied load and the shaft rotational speed. At last, after the test, the wear of top foil coating was inspected visually.