Patent ID: 8545175

Claim:
A system for controlling rotor blade over-tip leakage of a working fluid in a rotating machine, the system comprising: a circumferential row of rotor blades, a circumferential row of seal segments for sealing with radially outer tips of the rotor blades to reduce over-tip leakage of the working fluid, the seal segments having an inboard abradable layer which is adapted to be abraded by the blade tips to form a wear track for the blade tips, and at least one tip wearing body that is harder than the abradable layer, which is adapted to wear down the blade tips; wherein a thickness of the abradable layer 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 under normal operating conditions, and the wear track having a uniform radius is formed in the abradable layer by the blade tips, the at least one tip wearing body also wearing down the blade tips to provide a uniform blade tip radius.