Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Patent
1997-10-14
1999-04-27
Ryznic, John E.
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
F01D 518, F02C 718
Patent
active
058972943
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas turbine blade having a shower head cooling mechanism.
2. Description of the Prior Art
In an air cooled blade of a high temperature gas turbine, film cooling has now become established as an indispensable art. With reference to FIGS. 3 and 4, a conventional type of cooling is illustrated. FIG. 3 is a cross sectional view of the an air cooled blade, and FIG. 4 is a perspective view showing an arrangement of shower head cooling holes in a blade leading edge portion.
Generally in a high temperature gas turbine blade, as shown in FIG. 3, shower head cooling holes SC are provided in a blade leading edge portion. Film cooling holes FC are provided on an upstream side of the a blade dorsal portion and on a downstream side of a blade ventral portion and pin fin holes PC are provided in a blade trailing edge portion.
The shower head cooling holes SC, as shown in FIG. 4, are bored in a leading edge portion of a blade 2 so as to be arranged in a straight line toward a blade hub side HS from a blade tip side TS. Air is blown from the cooling holes in an opposite direction relative to the gas flow.
Shower cooling and film cooling relate to an art that enhances cooling efficiency by covering a blade surface with a cooling air that is blown over a gas flow surface.
If the cooling air is blown too strongly, however, the cooling air causes a peeling from the blade surface so as to mix with a main flow of the gas which results in a reduced effect of the film cooling, or if the cooling air is blown too weakly, it will not provide a proper cooling effect due to a shortage of the cooling air amount. Accordingly, these considerations must be taken into account so that the blade surface will be covered by an optimal film of air.
SUMMARY OF THE INVENTION
As mentioned above, if the shower head cooling holes SC are provided so as to oppose the direction of gas flow, there occurs a difference in a pressure distribution of gas between the blade tip side TS and the blade hub side HS according to the direction of swirling flow in a corresponding combustor.
On the other hand, as the pressure of the film cooling air is supplied at a constant level, there is a location where only a small differential pressure can be obtained, i.e., at a mid place between the tip portion and the hub portion. For this reason, there is a problem that flow velocity of the cooling air that is blown from the cooling holes is reduced, and thereby the cooling effect is adversely impacted.
It is therefore an object of the present invention to provide a gas turbine blade which solves the above problems and attains uniform cooling of the blade, and maintains a constant pressure irrespective of the location of the cooling holes.
In order to attain the object, the present invention provides a gas turbine blade in which a plurality of shower head cooling holes are bored in a blade leading edge portion. The cooling holes are arranged on one line so as to be biased either to a left hand side or to a right hand side, as seen from upstream of the blade, toward a blade hub side from a blade tip side according to direction of swirling flow in combustor. Thus, taking account of the direction of the swirling flow in the combustor which is disposed upstream of the blade, the shower head cooling holes are arranged on a line that is biased to the left hand side or to the right hand side, as seen from upstream, toward the blade hub side from the blade tip side. Thereby the gas pressure at each location of the cooling holes becomes constant in a blade height direction and the differential pressure from the cooling air pressure also becomes constant, and thus uniform cooling of the blade becomes attainable.
Also, the present invention provides a gas turbine blade in which the plurality of shower head cooling holes are arranged on one line so that the shower head cooling holes of the blade tip side are biased to the left hand side, as seen from upstream, of those of the blade hub side if t
REFERENCES:
patent: 3540811 (1970-11-01), Davis
patent: 3554663 (1971-01-01), Helms
patent: 3619082 (1971-11-01), Meginnis
patent: 3644060 (1972-02-01), Bryan
patent: 5486093 (1996-01-01), Auxier et al.
patent: 5779437 (1998-07-01), Abdel-Messeh et al.
Aoyama Kuniaki
Terazaki Masao
Mitsubishi Jukogyo Kabushiki Kaisha
Ryznic John E.
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