Gas turbine moving blade platform

Abstract: Provided is gas turbine moving blade platform wherein platform cooling structure is simplified with workability thereof being enhanced and cooling effect of platform side end portions is increased resulting in uniform cooling of entire platform. Cooling passages 2, 3 are bored in platform 1 front portion communicating with cooling air passage 52 of moving blade 51 and opening at both platform 1 side end surfaces. Openings thereof are inserted with covers 2a, 2b to be closed. Cooling passages 6, 4 are bored in platform 1 side end portions communicating with the cooling passages 2, 3, respectively, and opening at platform 1 rear end surface. Plurality of cooling holes 5 are bored communicating with the cooling passage 4 and opening at the platform 1 side end surface. Cooling air flows into the cooling passage 6 from the cooling passage 2 and into the cooling passage 4 and the cooling holes 5 from the cooling passage 3 and flows out as cooling air 70f, 70e, 70d, respectively. Thus, entire platform 1 is cooled uniformly wherein platform 1 side portions are cooled by the cooling holes 5, so that cooling performance is ensured and also workability of cooling lines is enhanced.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to a gas turbine moving blade platform constructed so as to enhance a cooling performance thereof. Description of the Prior Art: Fig. 2 is a cross sectional view of a representative prior art gas turbine moving blade platform, which is an example of that used for a moving blade of first stage. This prior art is disclosed in US-A 6,071,075. In Fig. 2, numeral 50 designates a platform in its entire form and numeral 51 designates a first stage moving blade. Numeral 52 designates a leading edge passage of the moving blade 51 and cooling passages 53, 54 are provided to this leading edge passage 52 communicating therewith and extending toward respective side portions of the platform 50. The cooling passages 53, 54 connect to cooling passages 55, 56, respectively, of both side portions and the cooling passages 55, 56 open at a rear end of the platform 50. In a front portion of the platform 50, there are provided cooling passages 57 and 58, 59 and 60, respectively, on both sides thereof and these cooling passages 57 to 60 are bored inclinedly from a lower surface toward an upper surface of the platform 50 to open at the upper surface so that cooling air is blown therefrom. Also, in a rear portion of the platform 50, there are bored cooling passages 61, 62, 63 to extend likewise inclinedly from the lower surface toward the upper surface of the platform 50 and to open at the rear end thereof so that the cooling air is blown therefrom. Further, in a central portion of the platform 50, there are provided cooling passages 64, 65, 66, 67, 68 and these cooling passages are also bored inclinedly from the lower surface toward the upper surface of the platform 50 so that the cooling air is blown from the upper surface, wherein an outlet end portion of each of the cooling passages 64 to 68 is worked to enlarge in a funnel-like shape so that the cooling air is diffused on the upper surface. Fig. 3 is a cross sectional view taken on line C-C of Fig. 2, wherein the cooling passages 55, 56 are provided in both side portions of the platform 50 and the cooling passage 67 is bored inclinedly from the lower surface toward the upper surface of the platform 50. Fig. 4 is a cross sectional view taken on line D-D of Fig. 2, wherein there are provided the cooling passage 55 extending from the front portion toward the rear portion of the platform 50 to open at the rear end and the cooling passages 57, 64 to 68 extending inclinedly, so that the cooling air is blown therethrough rearwardly and upwardly, respectively. In the platform 50 constructed as above, cooling air which has been supplied into the moving blade 51 through the leading edge passage 52 flows portionally into the cooling passages 55, 56 for cooling of both side portions of the platform 50 to then flow out of the rear end of the platform 50. Also, the cooling passages 57 to 60, 61 to 63, respectively, are provided inclinedly in the front and rear portions of the platform 50 so that cooling air is introduced thereinto from the lower surface of the platform 50 to flow out of the upper surface of the front and rear end portions of the platform 50. Further, the cooling passages 64 to 68 are provided inclinedly in the central portion and cooling air flows therethrough from the lower surface of the platform 50 to flow out of the upper surface thereof. Thus, the entire portion of the platform 50 is cooled by the cooling air flowing therein and flowing out thereof. In the representative prior art gas turbine moving blade platform as described above, there are provided the cooling passages 55, 56 which are main cooling passages extending linearly and in addition thereto, there are provided the multiplicity of cooling passages of the cooling passages 57 to 60, 61 to 63, etc., which pass through the platform 50 inclinedly and thus constitute comparatively long inclined routes. Hence, in the platform 50, there are provided many such cooling air supply passages and work process of the platform itself becomes complicated and such a cooling structure of platform has been expected as can be made simpler and still has an excellent cooling effect to cool uniformly the entire portion of the platform including peripheral side portions thereof where there is a severe thermal influence. It is therefore an object of the present invention to provide a gas turbine moving blade platform in which supply passages and flow passages of the platform cooling air are simplified so that work process of the platform is facilitated as well as cooling effect of the entire portion of the platform is maintained without being aggravated and especially the platform peripheral side portions are cooled effectively. In order to achieve said object, the present invention provides a gas turbine moving blade platform as defined in the claim 1. A gas turbine moving blade platform of the invention comprises two cooling passages, each being provided in said platform on each side of the moving blade, communicating at its one end with a leading edge passage of the moving blade and having at its the other end an opening at a side end surface of said platform; a cover for closing said opening of each of said two cooling passages; a side end portion cooling passage, being provided in each side end portion of said platform, communicating at its one end with each of said two cooling passages and having at its the other end an opening at a rear end surface of said platform; and a plurality of cooling holes, each communicating at its one end with any one of said side end portion cooling passages and having at its the other end an opening at the side end surface of said platform. In the platform of the invention, there are provided the side end portion cooling passages along both side end surfaces of the platform so that cooling air is introduced thereinto from the leading edge passage of the moving blade through the two cooling passages of the front portion of the platform for cooling of both side portions of the platform to then flow out of the openings at the rear end surface of the platform. Further, there are provided the plurality of cooling holes communicating with any one of the side end portion cooling passages, for example, the side end portion cooling passage on a dorsal side of the moving blade which is exposed to a high temperature combustion gas, and the cooling air is caused to flow from these cooling holes, thereby the side end portion of the platform where there is a severe thermal influence can be cooled effectively with result that the entire portion of the platform can be cooled uniformly. Still in the platform above, there is provided no such complicated and inclined cooling passage as used in the prior art and the cooling lines are constructed simply by the cooling passages extending along both side end surfaces and opening at the rear end surface, thereby the work process of the platform is facilitated. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 shows a gas turbine moving blade platform of an embodiment according to the present invention, wherein Fig. 1(a) is a plan view of the platform and Fig. 1(b) is a cross sectional view taken on line A-A of Fig. 1(a). Fig. 2 is a cross sectional view of a representative prior art gas turbine moving blade platform. Fig. 3 is a cross sectional view taken on line C-C of Fig. 2. Fig. 4 is a cross sectional view taken on line D-D of Fig. 2. DESCRIPTION OF THE PREFERRED EMBODIMENTS: Herebelow, description will be made concretely on embodiments according to the present invention with reference to figures. Fig. 1 shows a gas turbine moving blade platform of an embodiment according to the present invention, wherein Fig. 1(a) is a plan view of the platform and Fig. 1(b) is a cross sectional view taken on line A-A of Fig. 1(a). In Fig. 1, numeral 1 designates a platform and numeral 51 designates a moving blade. Numerals 2, 3 designate cooling passages, which are bored in the platform 1 extending right and left, respectively, of a leading edge portion of the moving blade 51, each to be arranged to communicate at its one end with a leading edge passage 52 and extend at its the other end toward a side end surface of the platform 1. Numeral 4 designates a cooling passage, which is bored in the platform 1 on a blade dorsal side along the side end surface of the platform 1 to be arranged to communicate at its front end with the cooling passage 3 and open at its rear end at a rear end surface of the platform 1. Further, there are provided in the side end portion of the platform 1 a multiplicity of cooling holes 5 each to be arranged to communicate at its one end with the cooling passage 4 and open at its the other end at the side end surface of the platform 1. Numeral 6 designates also a cooling passage, which is bored in the platform on a blade ventral side along the side end surface of the platform 1 to be arranged to communicate at its front end with the cooling passage 2 and open at its rear end at the rear end surface of the platform 1. Numerals 2a, 3a designate covers. The cover 2a is inserted into an opening of the cooling passage 2 for closing thereof and the cover 3a is inserted into an opening of the cooling passage 3 for closing thereof. By employing these covers 2a, 3a, when the cooling passages 2, 3 are to be worked in the platform 1, boring of the passages can be facilitated. That is, the cooling passages 2, 3 are completed such that boring work is done to pass through from the side end surfaces of the platform 1 toward the leading edge passage 52 of the moving blade 51 and then openings at the side end surfaces of the platform 1 are closed by the covers 2a, 3a, thus the boring work is simplified. In the platform 1 constructed as above, cooling air flows into the moving blade 51 from a blade base portion to flow toward a blade tip portion through the leading edge passage 52 and a portion thereof lows into the cooling passages 2, 3. The cooling air which has entered the cooling passages 2, 3 flows, as shown by arrows 70a, 70b, for cooling of a portion of the platform 1 around the leading edge portion of the moving blade 51 and then flows into the cooling passages 4, 6, respectively. Cooling air 70c which has entered the cooling passage 4 flows out of the multiplicity of cooling holes 5 sequentially on the way while flowing through the cooling passage 4 for cooling of the side end portion of the platform 1 on the blade dorsal side and remaining cooling air 70e flows out of an opening at the rear end surface of the platform 1. Thus, the side end portion of the platform 1 on the blade dorsal side and the blade leading edge portion which are exposed to a high temperature combustion gas with a severe thermal influence can be cooled efficiently. Cooling air 70f which has entered the cooling passage 6 flows through the cooling passage 6 as it is for cooling of the side end portion of the platform 1 on a downstream side of the combustion gas to then flow out of an opening at the rear end surface of the platform 1. In this case, there is provided to the cooling passage 6 none of the multiplicity of cooling holes extending toward the side end surface in consideration of workability of the platform 1 and cooling of the side end portion is effected only by the cooling air 70f flowing through the cooling passage 6, which at the same time takes minimum charge of the cooling of a portion approaching to the moving blade 51. According to the gas turbine moving blade platform of this embodiment of the present invention as described above, construction thereof is made by the minimum and simplified cooling passages such that the cooling air 70a, 70b is led from the leading edge passage 52 of the moving blade 51 to flow through the cooling passages 6, 4, respectively, for cooling both of the side end portions of the platform 1 and there are provided the multiplicity of cooling holes 5 only in the side end portion on the blade dorsal side where there is a severe thermal influence so that the cooling air from the cooling passage 4 is led thereinto for cooling of this side end portion to then flow out thereof as the cooling air 70d, thereby there is no need to provide many such complicated and inclined cooling passages as used in the prior art and an entire portion of the platform 1 is cooled efficiently and, in addition thereto, work process of the cooling lines of the platform 1 becomes facilitated. It is to be noted that, in the mentioned embodiment, although the example of the cooling passage 6 of a single piece has been described, the present invention is not limited thereto but may naturally be constructed by two pieces thereof, or even more pieces as the case may be, and the cooling passage 6 may not always be formed linearly.

Claims: A gas turbine moving blade platform comprising a first cooling passage (2,3) provided in said platform (1) on a side of a moving blade (51), communicating at its one end with a leading edge passage (52) of the moving blade (51) and having at its other end an opening at a side end surface of said platform (1); and a second cooling passage (4,6) provided in a side end portion of said platform (1), communicating at its one end with said first cooling passage (2,3) and having at its other end an opening at a rear end surface of'said platform (1); characterised by comprising a cover (2a,3a) for closing said opening of said first cooling passage (2,3), and a plurality of cooling holes (5), each communicating at its one end with said second cooling passage (4,6) and having at its other end an opening at the side end surface of said platform (1). The gas turbine moving blade platform according to claim 1, characterized in that said second cooling passage (4,6) is constructed of one or more pieces. The gas turbine moving blade platform according to claim 1 or 2, characterized in that there are provided two of said first cooling passages (2,3), one provided on each side of said moving blade (51), and two of said second cooling passages (4,6), one provided in each side end portion of the platform (1) and communicating with tone of said two first cooling passages (2, 3). The gas turbine moving blade platform.according to claim 3, characterized in that said plurality of cooling holes (5) are provided only at a dorsal side end surface of said platform (1).

Inventors: AKITA EIJI, FUKUE ICHIRO, SUENAGA KIYOSHI, TOMITA YASUOKI, AKITA, EIJI, FUKUE, ICHIRO, SUENAGA, KIYOSHI, TOMITA, YASUOKI, Akita, Eiji c/o Tagasago Machinery Works, Fukue, Ichiro c/o Tagasago Machinery Works, Suenaga, Kiyoshi c/o Tagasago Machinery Works, Tomita, Yasuoki c/o Tagasago Machinery Works
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI HEAVY INDUSTRIES, LTD.
Application year: 1999
Main classification: F01D5
IPC codes: F01D5