Flow directing assembly for the compression section of a rotary machine

A flow directing assembly for a compression section of a rotary machine which extends circumferentially about an axis R, which has a working medium flowpath, and which has an upstream end and a downstream end which comprises:

• an outer wall extending circumferentially about the axis R,
• an inner wall spaced radially from the outer wall leaving an annular passage for working medium gases extending therebetween,
• a plurality of airfoils spaced circumferentially and extending radially across the working medium flow path, each airfoil having an inner end, an outer end, a spanwise axis extending between the ends, and
• a plurality of airfoil sections disposed about the spanwise axis,
• each airfoil section having an aerodynamic surface and having a leading edge, a trailing edge, a pressure surface, and a suction surface extending from the leading edge to the trailing edge which form the aerodynamic surface of the airfoil, the suction surface, and the pressure surface having a thickness therebetween and diverging in the downstream (chordwise) direction from the leading edge increasing the circumferential thickness to a maximum and converging thereafter decreasing the thickness to the training edge;
• wherein at least one of said airfoils extends from at least one of the walls, said wall from which the airfoil extends extending axially and circumferentially between the airfoils and between the leading edge and the trailing edge, the wall from which the airfoil extends having a first region which extends circumferentially from leading edge to leading edge and downstream a distance which is less than or equal to one-fourth of the axial length L.sub.a from leading edge to trailing edge, the wall being convex toward the flowpath in the first region;
• the wall having a second region which extends from trailing edge to trailing edge and extends upstream a distance which is less than or equal to one-fourth of the axial length L.sub.a, the wall being convex toward the flowpath in the second region;
• the wall having a third region which extends from the first region to the second region and circumferentially from airfoil to airfoil, the wall in the third region being concave toward the flowpath;
• and, wherein the convex region, the second convex region, and the concave region, respectively, have their maximum extent (a point of zero slope) at the leading edge, the trailing edge, and the thickest portion of the airfoil as measured with respect to the line of intersection of a radial plane and a conical surface passing through the leading edge and trailing edge at the wall.