| 摘要 |
The invention contemplates a bow-measuring instrument in which simultaneous evaluation of the bow in a turbine vane is made at offset alignments, on both the convex and the concave surfaces of the airfoil section of the vane. The offsets are selected, for each type vane, so as to critically observe the extent of bow at or near the local regions at which these surfaces cooperate to define a nozzle throat, when vanes are assembled in side-by-side circumferential adjacency in a given gas-turbine stage; specifically, the "high point" in the center of the airfoil is observed for bow, at the center and along the alignment of the die-loading, in the hot-forming correction of vane shape. In this manner, a simple gaging operation helps to achieve greatly enhanced control of the uniformity and correct sizing of all nozzle-throat areas in a given stage of the turbine; and much better referencing is obtained for further gaging techniques.
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