An article and method of cooling an article are provided. The article includes a body portion having an inner surface and an outer surface, the inner surface defining an inner region, and at least one cooling feature positioned within the inner region. At least one of the inner surface of the body portion and the at least one cooling feature has a surface roughness of between about 100 microinches (about 2.54 microns) and about 3,000 microinches (about 76.2 microns). The method of forming an article includes manufacturing a body portion by an additive manufacturing technique, and manufacturing at least one cooling feature by the additive manufacturing technique. The additive manufacturing integrally forms a surface roughness of between about 100 microinches (about 2.54 microns) and about 3,000 microinches (about 76.2 microns) on at least one of an inner surface of the body portion and the at least one cooling feature.

An axial fan includes a hub attachable to a rotary shaft, and five or less blades arranged on the hub. Each blade includes a leading edge located forward in a rotation direction of the rotary shaft, a trailing edge located rearward in the rotation direction of the rotary shaft, and a porous part. A dimension from the leading edge to the trailing edge is a blade chord length, and the porous part is arranged at a position located rearward from the leading edge by 40% or more of the blade chord length.

A turbine airfoil comprises an airfoil defining a leading edge, a trailing edge, a root portion, a tip portion, a chord line defining a chord length of the airfoil, a suction side surface extending in a spanwise direction from the root portion to the tip portion and in a flow-wise direction between the leading edge and the trailing edge, and a throat line extending spanwise along the suction side surface from the root portion to the tip portion. The turbine airfoil further includes a plurality of micro-riblet patches defined along the suction side surface aft of the throat line where each micro-riblet patch of the plurality of micro-riblet patches extends in the flow-wise direction between the throat line and the trailing edge.

A turbine blade and related method are disclosed. The blade includes an airfoil body having a radial outermost surface relative to a turbine rotor, a bond coat over the radial outermost surface, and an outermost abrasive layer over the bond coat. The outermost abrasive layer may include a graded oxide ceramic layer or a graded metal ceramic layer. In any event, the outermost abrasive layer is vacuum heat treated to harden the layer, resulting in increased rub and improved clearance between the blade tip, creating a smaller tip gap and lower leakage compared to conventional systems. The heat-treated abrasive layer is also resistant to oxidation at higher temperatures, e.g., greater than 1090 C. (2000F.), caused by the increased use of higher temperature fuels, such as hydrogen. The vacuum heat treatment also results in thermal cycle testing improvements.