Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Patent
1999-02-22
2000-11-14
Look, Edward K.
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
416191, B63H 114
Patent
active
061460982
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a gas turbine cooled blade tip shroud and, more particularly, to a tip shroud for a moving blade, which is made light at a downstream stage of the gas turbine and which is cooled not only from its inside but also from its outside.
DESCRIPTION OF RELATED ART
In recent years, the gas turbine has advanced to have elongated moving blades that are subjected to higher temperatures and output. Especially a downstream stage moving blade is remarkably elongated to 50 to 60 cm, for example. This long moving blade has a large weight and accordingly a serious vibration so that the stress to be generated by the centrifugal force at the time of rotation becomes far higher than that of the prior art. Therefore, this moving blade is thinned as much as possible so that it may be lighter, and its width is tapered to grow smaller toward the end portion.
FIGS. 6(a)-(b) show an example of the prior art moving blade, FIG. 6(a) is a longitudinal section, and FIG. 6(b) is a section taken along line D--D of FIG. 6(a). In FIG. 6(a), reference numeral 50 designates a moving blade having a blade root 51 and a hub 53. Numeral 54 designates a hub which has a cavity 55 therein as long as 25% of the blade length. Numeral 56 designates a number of pin fins protruding inward of the cavity 55 or connected to the two opposing cavity walls. Numeral 57 designates core supporting ribs. Numeral 58 designates holes for feeding cooling air. These holes 58 are arrayed in a large number from the portion of the 25% blade length, as shown in FIG. 6(b), and extend to a blade end 59. Numeral 60 designates a tip shroud at the leading end.
FIGS. 7(a)-(b) show the tip shroud, FIG. 7(a) is a view taken in the direction of arrows E--E of FIG. 6(a), and FIG. 7(b) is a view taken in the direction of arrows F--F of FIG. 7(a). In FIG. 7(a), numeral 61 designates a number of air passages formed along the inner face of the tip shroud 60 and having openings 62. In the moving blade thus constructed, the cooling air from the blade root 51 enters the cavity 55 so that it is disturbed by the pin fins 56 into a turbulent state to cool the hub 54 in an enhanced cooling effect. Then, the cooling air flows through the holes 58 into the air passages 61 of the tip shroud 60 while cooling the blade and cooling the tip shroud 60 from the inside until the air is finally released from right and left openings 62 to the combustion gas passage.
FIG. 8 shows an improvement over the aforementioned moving blade 50 shown in FIGS. 6 and 7. In this example of the moving blade, the work of boring the holes is eliminated to improve the workability, and the porosity is improved to improve the cooling efficiency, as has been applied for patent by the Applicant. In FIG. 8, numeral 40 designates a moving blade having a blade root 41 and a hub 42. This moving blade 40 has a cavity which is supported by a number of core supporting ribs 43 extending in the longitudinal direction of the blade. On the inner wall of the cavity, on the other hand, there are provided multiple stages of oblique turbulators 44. FIG. 9 is a section taken along line G--G of FIG. 8 and shows the oblique turbulators 44 which protrude from the inner wall for disturbing the inflows of the cooling air to enhance the cooling efficiency. Numeral 45 designates openings which are formed in the front and back of a tip shroud 46 at the leading end to provide exits for the cooling air. The numeral 46 designates the tip shroud at the leading end.
In the moving blade thus constructed, the cooling air 30 flows from below the blade root 41 into the moving blade 40 toward the leading end of the cavity. In this course, the cooling air 30 is disturbed by the oblique turbulators 44 to enhance its cooling effect which extracts the heat in the inside of the moving blade 40 until the air finally flows from the openings 45 at the leading end of the tip shroud 46 to the combustion gas passage. Here, the tip shroud 46 is similar to that shown in FIG. 7, and its description will be omitted.
FIGS.
REFERENCES:
patent: 5460486 (1995-10-01), Evans et al.
patent: 5482435 (1996-01-01), Dorris et al.
patent: 5785496 (1998-07-01), Tomita
Fukuno Hiroki
Ito Eisaku
Tomita Yasuoki
Look Edward K.
Mitsubishi Heavy Industries Ltd.
Rodriguez Hermes
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