Forming a flow directing element for a turbine
AssigneeUnited Technologies Corporation
InventorThomas E. Dorman
Life of this patent
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Abstract
A flow directing element for the turbine section of a rotary machine includes various construction details which are developed which increase the aerodynamic efficiency of the flow directing element. In one embodiment, the flow directing element is a rotor blade having a roughened surface which approximates the critical roughness characteristic of the airfoil. In one particular embodiment, the roughness average of the surface lies between 120 to 200 AA microinches.
Claims9
A method for forming a flow directing element for a turbine of a rotary machine, the flow directing element having an airfoil and a flow of gases over the airfoil under operative conditions comprising:
- establishing a critical roughness characteristic for the flow directing element by establishing a representative Reynolds number for flow passing through the airfoil under a preselected operative condition of the machine;
- forming the flow directing element having the airfoil, the airfoil having a leading edge and a trailing edge which extend spanwisely and a convex suction side surface and a concave pressure side surface which extend chordwisely from the leading edge to the trailing edge, the convex surface having a roughened surface having a surface roughness that is within twenty (20) percent of the critical roughness characteristic and that is spaced chordwisely from the leading edge and the trailing edge.
A method for forming a flow directing element for the turbine of a rotary machine having a plurality of operative conditions, the machine having a preselected operative condition such as the cruise operative condition at which the machine operates for a length of time greater than other operative conditions of the engine and at which the flow directing element is operative in a flow having a representative Reynolds number for that condition, comprising:
- determining the critical roughness characteristic for the flow directing element associated with the representative Reynolds number for that preselected operative condition of the machine;
- forming a flow directing element having an airfoil which has a leading edge and a trailing edge which extend spanwisely and a convex side surface and a concave side surface which extend chordwisely from the leading edge to the trailing edge, the convex surface having a roughened surface that is within twenty (20) percent of the critical roughness characteristic and that is spaced chordwisely from the leading edge and the trailing edge.
Dependencies are inferred from the claim text.