| 摘要 |
A turbine blade tip clearance control system has a rigid two part outer casing (42) which sandwiches a control ring (48) therebetween, and an air pressurised flexible inner casing (28) which carries shroud segments (22) within it. Struts (40) span the annular space between the casings (42, 28) and prevent flexing of casing (28) until blade tip clearance needs adjusting, whereupon, ring (48) is heated, along with the adjacent portion of outer casing (42) and expands, allowing casing (28) to flex outwards, thus lifting the shroud segments (22) away from the blade tips (24). Closure of the tip clearance is achieved by cooling ring (48), the resulting contraction thereof, via the struts (40), flexing the inner casing (28) and shroud segments (22) inwards, against the air pressure.
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