Fluid reaction surfaces (i.e. – impellers) – With heating – cooling or thermal insulation means – Changing state mass within or fluid flow through working...
Reexamination Certificate
2001-09-28
2003-05-20
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With heating, cooling or thermal insulation means
Changing state mass within or fluid flow through working...
Reexamination Certificate
active
06565318
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a cast gas turbine blade/vane through which coolant flows, in particular a gas turbine rotor blade with a blade root, which is inserted into a rotatable disk of the gas turbine and which has a plurality of supply ducts for an internal cooling system, and a distribution space. Preferably, it is possible to feed coolant to the supply ducts by way of a feed duct of the disk, wherein the feed duct communicates with the supply ducts via the distribution space. The invention also preferably relates to an appliance, for casting a gas turbine blade/vane, having a casting core which has core ribs forming the supply ducts. Finally, the invention also preferably relates to a method of manufacturing a cast gas turbine blade/vane.
BACKGROUND OF THE INVENTION
From U.S. Pat. No. 4,344,738, a gas turbine blade/vane is known which is inserted by means of a blade root into a transverse groove of a rotatable disk of the gas turbine, the disk having a feed duct for supplying the gas turbine with coolant. Below the blade/vane root, the feed duct opens into the disk transverse groove intended for accommodating the blade/vane root. Supply ducts, through which the coolant is fed into the internal cooling system, emerge from the blade root. The supply ducts have, in the main, inlet openings with edges.
U.S. Pat. No. 4,992,026 reveals a gas turbine blade/vane through which a coolant flows and which has an internal cooling system, the coolant being introduced by feed ducts into the blade root and fed through supply ducts into the internal cooling system. At their transitions from the blade root, the supply ducts have right-angle edges.
The object of the internal cooling of the gas turbine blade/vane is to prevent severe heating of the blade/vane material, which occurs due to high operating temperatures and can lead to serious damage. For this purpose, it is necessary that the cooling medium should, without difficulty, reach the gas turbine blade/vane parts which, in particular, are remote from the inlet flow region and are exposed to the most severe effects. In the vicinity of the supply duct inlets which, however, have practically no cooling requirement, dead zones occur. Further, the flows depart greatly from the ideal laminar process in the case of inlets, which are greatly constructed with edges, to the supply ducts leading to the internal cooling system, such as is published in U.S. Pat. No. 4,344,738 or U.S. Pat. No. 4,992,026, for example. This, for example, involves an increased danger of the formation of deposits and, in particular, a high flow resistance. It is only possible to force the cooling medium through the supply passages by means of an increased pressure and this is frequently impossible to a sufficient extent.
A further possibility for forming the supply duct region in the lower blade root consists in providing a so-called distribution space from which the supply ducts for the internal cooling system emerge and which is supplied with coolant by the feed duct in the disk. Essentially, the distribution space should serve to provide a reliable and uniform distribution of the coolant to the supply ducts and it is only permissible for small coolant losses to occur. In the usual casting process, this distribution space generally has a rectangular configuration and has, in particular, right-angle transitions between the supply ducts and distribution space. Due to the construction with edges of the inlets to the supply ducts, strong flow eddies occur which, in principle, ensure good cooling of the regions over which flow occurs. Because, however, the distribution space is in the blade/vane root, it is not subject to severe heating effects and has, therefore, only a small cooling requirement.
This state of affairs can be improved by mechanical reworking, after the casting process, of the supply duct inlets from the distribution space. Because of the geometry of the blade root and the properties of the blade/vane material, however, this must generally take place manually and is, in consequence, very labor-intensive. Furthermore, this procedure does not ensure that all the supply ducts of a gas turbine blade/vane have the desired shape and that all the gas turbine blades/vanes of a type have the same flow resistance. This, however, would be necessary for a calculation in advance of the flow properties which would satisfy the high quality requirements and would be necessary for optimum utilization of the cooling medium.
SUMMARY OF THE INVENTION
An object of the invention is therefore to provide a cast gas turbine blade/vane, in particular a gas turbine rotor blade, through which coolant flows. It further preferably has transitions from the distribution space to the supply ducts which are optimized in terms of flow, i.e. which has low flow resistance at the outlet openings from the distribution space. An object is to be able to manufacture the distribution space and the internal cooling system in a single manufacturing process, the casting process. A further object of the invention includes providing an appliance and a method for manufacturing such a cast gas turbine blade/vane, through which coolant flows, with a corresponding distribution space.
An object directed toward a cast gas turbine blade/vane through which coolant flows is achieved by a cast distribution space being present which has rounded or beveled inlet openings to the supply ducts, for example.
The rounded or beveled inlet openings to the supply ducts, which are adjacent to the distribution space, ensure that the flow resistance to the cooling medium is minimized, particularly in the transition region between the distribution space and the supply ducts. The cooling medium flow remains substantially laminar. The coolant can therefore—given an appropriate edge-free transition solution from the feed duct to the distribution space—flow almost unhindered into the distribution space and out of it through the supply ducts. In this way, it reaches the internal cooling system rapidly and with low losses, which leads to a greatly increased service life, particularly in the case of the hot and coolant-intensive regions of the gas turbine blade/vane, for example the leading edge region. The coolant supplied is thus utilized better.
It is no longer necessary for the medium supplied through the feed duct of the disk to be guided round two 90° angles into the internal cooling system. On the contrary, it is fed directly to the internal cooling system in a smooth, continuous flow motion. No cavitation, in which the coolant is at rest as in dead zones, occurs while the cooling medium flows round. Because of the rounding or beveling of the inlet openings, the cooling medium supplied is only eddied to a very slight extent.
The inlet openings to the supply ducts abut directly onto the distribution space and are generated with it during one manufacturing process. The rounding or beveling is shaped by the casting process in a reproducible manner. In this way, a series of gas turbine blades/vanes can have the same, predetermined sizes and dimensions for the inlet openings and the distribution space. This provides the basis for a reliable determination in advance of the coolant requirement and/or the coolant function. This is particularly important for ensuring that even remote parts of the gas turbine rotor blades are reliably cooled and that, therefore, the wear due to overheating is minimized.
Due to the present invention, the coolant has already been introduced through the distribution space into the supply ducts at a low pressure because of the low flow resistance and it therefore escapes to only a small extent through the intermediate space between the blade root and rotating gas turbine disk. By this means, the coolant losses are minimized and the coolant is utilized in an optimum manner.
Because the distribution space has a configuration rounded in the manner of an ellipsoid, the cooling air can be fed particularly advantageously to the supply ducts. In this arrangement, the distribution space is pr
Harness Dickey & Pierce PLC
Look Edward K.
McCoy Kimya N
LandOfFree
Cast gas turbine blade through which coolant flows, together... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Cast gas turbine blade through which coolant flows, together..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Cast gas turbine blade through which coolant flows, together... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3052434