1. Field of the Invention
The present invention relates to an airfoil for use in a gas turbine engine, either as a blade or a vane, in which the airfoil includes a plurality of porous metal filled cavities with a thermal barrier coating applied over the porous metal, the porous metal allowing cooling air to flow through it onto the TBC producing a cooling air film to cool the airfoil.
2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98
Prior art airfoils use a variety of ways to cool the airfoil using cooling air passing through and over the surface of the airfoil. U.S. Pat. No. 4,629,397 issued to Schweitzer on Dec. 16, 1986 shows an airfoil (
The present invention provides an airfoil used in a gas turbine engine which includes a plurality of open ducts or cavities, these cavities being filled with a porous metal material to allow cooling air to pass through the porous metal, and a thermal barrier coating (TBC) applied on top of the porous metal, the TBC having cooling air holes to allow for the cooling air passing through the porous metal to flow onto the outer surface of the TBC to cool the airfoil. Cooling holes are located in the base of the cavities and through the TBC to allow cooling fluid to flow from within the airfoil to the external surface of the TBC. The porous metal acts as a support for the TBC, and also provides improved heat transfer from the airfoil to the cooling air passing through the porous metal since the porous metal better dissipates the heat throughout itself. The porous metal also acts to spread out the flow of cooling air as the cooling air passes through the porous metal, thereby increasing the heat transfer effect.
A gas turbine engine includes airfoils within the direct the flow of gas passing through it and to remove power from flowing gas. The airfoil can be either a rotary blade or a guide vane. An airfoil 10 of the blade type is shown in
The cooling holes 18 in the base 15 of the cavity is located on an opposite side of the cavity 12 than the cooling holes 20 in the TBC in order to force the cooling air passing through the porous metal 24 to pass through as much of the porous metal 24 as possible, thereby increasing the heat transfer effect of the porous metal 24 to the cooling air.
The porous metal used in the present invention can be any of the well-known porous metals used in gas turbine engines. The preferred material would be one that has a high melting point, and a high conductivity to magnify the effective cooling passage heat transfer coefficient at high temperatures found in the gas turbine art.
The size and shape of the cavities can be varied to provide any desired heat transfer effect. Cavity shapes can be square as shown in the Figures, rectangular, triangular, or even oval. The depth to width ratio of the cavity would depend upon the strength required for the side walls to support. TBCs having high strengths can be supported by larger cavities. The packing density of the porous metal can be regulated or varied within the airfoil to effect heat transfer rates. Even the relative density of the porous metal within a cavity can be varied to affect the heat transfer rate. Providing a higher density of porous metal at the interface of the TBC will improve the strength of the porous metal to secure the TBC.
This application claims the benefit to an earlier co-pending Provisional Application Ser. No. 60/677,900 filed on May 5, 2005 and entitled Airfoil Having Porous Metal Filled Cavities.
Number | Date | Country | |
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60677900 | May 2005 | US |