HIGH-TEMPERATURE POWDER-LUBRICATED DAMPERS FOR GAS-TURBINE ENGINES

This paper presents a novel powder-lubricated rotor bearing system damper concept for use in high-temperature, high-speed rotating machinery such as advanced aircraft gas turbine engines. Subscale tests of a damper segment were performed to evaluate the feasibility of the high-temperature damper concept at temperatures to 800-degrees-F and speeds to 10,000 rpm. These tests have shown that the introduction of a lubricating powder into the contact area between the nutating disk and a friction pad has two desirable effects. First, wear is minimized or eliminated, greatly extending damper life. Second, the introduction of powder between the two damper surfaces modifies the energy dissipation mechanism. The shearing of the powder in the contact area produces a damping force that more closely resembles that found in a hydrodynamic damper than that found in a classical Coulomb friction damper. The theoretical model that has been developed is based on a quasihydrodynamic lubrication theory and is also presented.