Abstract
Stiffness and damping coefficients of the clearance flow in balance disk models were measured in experiments and evaluated by calculations based on the bulk flow model. In the case of radially outward flow, it was found in experiments that the stiffness coefficient was negative in higher frequencies of axial oscillation in the parallel flow path and in all frequencies in the flow path which enlarged radially outward. In the case of radially inward flow, the stiffness coefficient was negative in the parallel flow path and the flow path which enlarged radially inward. The absolute values of the stiffness coefficient in the flow path which enlarged to the flow direction were larger than those in the parallel flow path.
