GB1226894A - - Google Patents

Abstract

1,226,894. Turbines. LICENTIA PATENTVERWALTUNGS - G. m. b. H. May 19, 1969 [May 25, 1968], No. 26526/69. Heading F1T. [Also in Division G2] A test rig for simulating the working loads acting on a steam turbine rotor blade 2 to enable examination of the behaviour at the connection between the blade root and the rotor periphery comprises an upper yoke 5 supported from a lower yoke 8 and a hydraulic device 15 for applying a tension force to the blade 2 and to a rotor segment 3 to which the blade is secured by a straddle type root fixing. The region of the fixing can be heated. The blade 2 is secured to the yoke 5 by welding the tip shroud 18 to a plate 19 which is bolted to the yoke 5. The rotor segment 3 is secured to a rod 4 which in turn is attached to a threaded tensioning rod 16 connected to hydraulic device 15. The rod 4 is guided in a bush 17 secured to yoke 8. The latter supports yoke 5 by way of sleeves 12, 14 and spring members 11, 13 consisting of stacks of metal and rubber sheets. The hydraulic device 15 can thus apply to the blade 2 and rotor segment 3 loads corresponding to the centrifugal loads experienced during turbine operation. Loads corresponding to axial and/or circumferential steam loads, depending on the position of the blade 2 in relation to the yoke 5, can be applied to the blade by a metal cable 31 having a loop 30 around the blade. The cable 31 is anchored at both ends and includes a spring 33, adjuster 32 and a device comprising a rotating disc 36 and an arm 35 for applying a cyclically varying force to the cable 31, e.g. at a frequency of 3 cycles/sec. A second such device may be provided at the other end of the cable 31 for applying a similar force in the opposite direction. Any slippage, tilting, or deformation of the blade root in relation to the rotor segment 3 can be detected by an optical system, Figs. 3, 4 (not shown), and dial gauges. The optical system comprises mirrors (20, 21) on the sides of the blade root and rotor segment respectively and a calibrated screen (23) upon which images of a light source (22) are reflected by the mirrors. If any relative movement between the root and rotor segment occurs, then the images on screen (23) move apart.