Abstract: A method of and device for avoiding rotor instability thereby increasing the dynamic power limit of rotary fluid machines such as turbines and compressors which have contact free seals in the gaps between the rotating and nonrotating elements of the machine in which the rotary flow of fluid in the gap is modified as by axial baffles in the gap or by introducing a fluid medium into the gap thereby to decrease, eliminate, or even reverse the force component acting on the rotating element and disposed 90.degree. ahead of the oscillation deflection of the rotating element.

Abstract: A method of and devices for avoiding rotor instability thereby increasing the dynamic power limit of rotary fluid machines such as turbines and compressors which have contact free seals in the gaps between the rotating and nonrotating elements of the machine in which the rotary flow of fluid in the gap is modified as by axial baffles in the gap or by introducing a fluid medium into the gap thereby to decrease, eliminate, or even reverse the force component acting on the rotating element and disposed 90.degree. ahead of the oscillation deflection of the rotating element.