Abstract: Some embodiments control rotor blade over-tip leakage of a working fluid in a rotating machine, which includes a circumferential row of rotor blades. A circumferential row of seal segments seal with the radially outer tips of the rotor blades to reduce over-tip leakage of the working fluid. The seal segments have an inboard abradable layer adapted to be abraded by the blade tips to form a wear track for the blade tips. Tip wearing bodies are adapted to wear down the blade tips. The abradable layer thickness and cold build radial positions of the blade tips, seal segments, and tip wearing bodies are arranged such that, during running-in of the machine, a wear track having a uniform radius is formed in the abradable layer by the blade tips, and the tip wearing bodies wear down the blade tips to provide a uniform blade tip radius.

Abstract: A system is provided for controlling rotor blade over-tip leakage of a working fluid in rotating machine. The system has a circumferential row of rotor blades, and a circumferential row of seal segments for sealing with the radially outer tips of the rotor blades to reduce over-tip leakage of the working fluid. The seal segments have an inboard abradable layer which is adapted to be abraded by the blade tips to form a wear track for the blade tips. The system further has one or more tip wearing bodies which are adapted to wear down the blade tips. The thickness of the abradable layer and the cold build radial positions of the blade tips, seal segments and tip wearing bodies are arranged such that, during running-in of the machine, a wear track having a uniform radius is formed in the abradable layer by the blade tips, and the tip wearing bodies also wear down the blade tips to provide a uniform blade tip radius.