DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Figure I illustrates an isometric vievv of rotor drum depicting the locking arrangement of closing blade and adjacent blades to rotor drum in accordance with the present invention.
Figure 2(a) illustrates an axial section of a rotor drum of figure 1 without blades and locking arrangement.
Figure 2(b) illustrates an axial section of a rotor drum of figure 1 without blades.
Figure 3(a) illustrates an axial section cut across the mid section of the locking arrangement and looking from side 'A! as indicated in figure 1.
Figure 3(b) illustrates an enlarged view of marked portion of locking arrangement of figure 3(a).
Figure 4 illustrates an enlarged vievv of two wedges of locking arrangement of figure 1.
in accordance with the present invention, there is provided a locking arrangement for locking of a_closing blade 12 in a rotor drum 11 row of blades comprising a rotor drum 14. two wedges 16 and 18 and a Screw 20.
The blades are of T-root shape and a complementary T-root groove 13 is machined in the rotor drum 14 to mate with the T-root of the blades and thereby facilitate in holding the blades to the rotor drum 14. The profile changing edges of the T-root of the blade and T-root groove 13 are either filleted or chamfered considering assembly constraints. A slot 15 is made on the rotor drum 14 at each stage to facilitate assembling of blades in the rotor drum 14 as it is not possible to radially enter the blades in the rotor drum 14 without drilling the slot 15 as the complementary projections 'P' provided in the s4et-T root groove 13 to mate with the leg 'L' of the T-mot will object the entry of the base of the T-root blades. The slot 15 is made on the
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rotor drum 14 in such a way that the vertical face VI of the slot 15 is inclined at an angle 10 degrees to the vertical and horizontal face Hl of the slot 15 is a combination of tapered and flat face thereby forming a filleted edge FE at the joining of the vertical face VI and horizontal face Hl. The wedge 16 is made in such a way that it will have similar shape of the removed piece of the slot 15 on one side and align with the projections 'P' of the T-root stet- aroove 13 of the rotor drum 14 when the wedge 16 is adapted to mate with the leg 'L' of the T-root closing blade 12 as shown in figure 3(b). The other side of the wedge 16 is tapered with a half-way threaded hole H2 drilled at the mid section on operative top. The edges of the wedge 16 are chamfered on the two side faces at the base to facilitate in assembling. The wedge 18 is of cubical shape with filleted edges on two corners and sharp edges on other two corners around the perimeter. All the edges at the base of the wedge 18 are chamfered to facilitate in assembling. A half-way threaded hole H3 is provided on side of the wedge 18 which adjoins the tapered side of the wedge 16 complementary to the half-way threaded hole H2of the wedge 16. The Screw 20 is inserted in to the threaded hole H4 formed by adjoining half way threaded holes (H2 and H3) of the wedges 16 and 18 to hold the wedges 16 and 18 locked in position during rotation of the rotor drum 14. The locking arrangement is provided at different positions around the circumference of rotor drum 14 across the rows of blades.
The method of locking of closing blades 12 in the rotor drum 14 is as follows: All the blades are made to slide through the stet-T-root groovel3 of the rotor drum 14 tili the closing blade 12 is placed in the position parallel to the slot 15 of the rotor drum 14. The wedges 16 and 18 are configured in the slot 15 of the rotor drum 14 to mount against the closing blade 12. The two wedges 16 and 18 are held in position by means of the Screw 20.
TEST RESULTS:
Figure 5 illustrates test results of the analysis performed at steady-state conditions on section of the rotor drum as shown in figure 1. Simulations are run by applying the boundary conditions like restricting the axial movement of the section and a frictional