Turbine airfoil with micro cooling channels
An air cooled turbine airfoil having micro cooling air passages formed within the airfoil that is of such size that the present day investment coating process cannot be used. The internal cooling air features of the airfoil are formed using the Tomo Lithographic Molding (TLM) process. The TLM process is a low pressure casting process that can produce precise micro-features integral to macro-scale structures using any of the exotic alloys or other metallic materials currently being used in airfoil production. The normal internal cooling air passages as well as very small features such as trip strips, pin fins, dimples, pedestals and enclosed passages such as film holes can be produced using the TLM process.
1. An air cooled turbine airfoil comprising:
a pressure side wall and a suction side wall;
a leading edge region and a trailing edge region extending between the pressure side wall and the suction side wall;
a first radial extending cooling channel located adjacent to the trailing edge region;
a trailing edge region cooling channel formed between the pressure side wall and the suction side wall;
a first row of metering holes connected between the radial extending cooling channel and the trailing edge region cooling channel;
three rows of trip strips extending across the trailing edge region cooling channel;
a row of axial ribs forming diffusion sections that open into exit slots on the pressure side wall adjacent to a trailing edge of the airfoil;
three rows of pedestals connecting the rows of trip strips and forming a zip-zap shape; and,
a row of exit holes connected to the exit slots and opening onto the trailing edge of the airfoil.
2. The air cooled turbine airfoil of claim 1 , and further comprising:
the trip strips and the pedestals are too small to be formed from an investment casting process.
3. The air cooled turbine airfoil of claim 1 , and further comprising:
a plurality of spanwise extending dimples along the walls of the trailing edge region cooling channel and located between the rows of pedestals.
4. The air cooled turbine airfoil of claim 1 , and further comprising:
a second radial extending cooling channel located forward of the first radial extending cooling channel; and,
a second row of metering holes connecting the second radial extending cooling channel to the first radial extending cooling channel.
5. The air cooled turbine airfoil of claim 4 , and further comprising:
the second row of metering holes is located adjacent to the pressure side wall.
6. The air cooled turbine airfoil of claim 5 , and further comprising:
a shaped film cooling hole connected to the second radial extending cooling channel; and,
a row of suck-back holes connecting the row of film cooling holes to the first radial extending cooling channel.
7. The air cooled turbine airfoil of claim 1 , and further comprising:
the row of exit holes opening on the trailing edge are of less than 0.010 inches in diameter.