Rigid and rotatable vanes molded within variably shaped flexible airfoils
Airfoils ( 12 ) are molded of material ( 28 ), such as silicon rubber, which is fluent during molding, becoming solid and compliant at temperatures of use, with rigidly fixed vanes ( 25 ) and rotatable vanes ( 26 ), as inserts which are co-molded within the airfoil. The inserts are pre-prepared of either stiff or semi-stiff material to suit the intended needs of the airfoil. Then, with inserts in place within a mold, the airfoil is molded of compliant material. At least one of the inserts ( 26 ) is rotatable so as to force at least some portion of the compliant airfoil to alter camber, the compliant material between the inserts smoothing out the surface of the airfoil. The airfoils thus molded are then inserted between the inner hub ( 18 ) and the outer ring ( 22 ) of the rotary machine in which a fan or compressor is being constructed. Rods of the movable vanes extend to a unison ring connected ( 32 ) to rotate the vanes.
1. An airfoil for a rotary fan or compressor, comprising:
a circumferential thickness increasing from nil at a trailing edge and decreasing to a leading edge, a radial length extending between a radially inward flank and a radially outward flank, and an axial width extending from the leading edge to the trailing edge;
characterized by:
a non-rotatable vane having a radial length which extends radially inwardly from the inward flank and radially outwardly from the outward flank, having an axial width less than the axial width of the airfoil;
at least one rotatable vane having a radial length less than the radial length of the airfoil, having an axial width less than the axial width of the airfoil, and including a rod extending from the at least one rotatable vane radially outwardly from the outward flank;
and a solid, compliant, molded material, co-molded with the non-rotatable vane and the at least one rotatable vane in place and circumferentially centered within a mold, the thickness of each vane of the non-rotatable vane and the at least one rotatable vane being less than the thickness of the airfoil at the respective position of said each vane.
2. An airfoil according to claim 1 further characterized in that:
said at least one rotatable vane is in a position within said airfoil which is closer to the trailing edge of the airfoil than a position of the non-rotatable vane.
3. An airfoil according to claim 1 further characterized in that:
said at least one rotatable vane is in a position within said airfoil which is closer to the leading edge of the airfoil than a position of the non-rotatable vane.
4. An airfoil according to claim 1 further characterized in that:
said at least one rotatable vane includes a first rotatable vane with a hollow rod having an inner diameter, and a second rotatable vane with a solid rod having an outer diameter less than the inner diameter of the hollow rod, and the solid rod having a radial length longer than the radial length of the first rotatable vane including the hollow rod; and
the first rotatable vane is positioned near the outer flank of the airfoil and the second vane is positioned near the inner flank of the airfoil with the solid rod passing through the hollow rod of the second rotatable vane.
5. An airfoil according to claim 1 further characterized in that:
said at least one rotatable vane includes a first rotatable vane with a first rod, and a second rotatable vane with a second rod which has a radial length longer than the radial length of the first rotatable vane including the first rod; and
the first rotatable vane is positioned near the outer flank of the airfoil and the second rotatable vane is positioned near the inner flank of the airfoil with the second rod axially forward of the first rotatable vane including the first rod.
6. A method of forming an airfoil, characterized by:
pre-forming a non-rotatable vane which is to extend outwardly from inner and outer flanks of the airfoil to be formed, said non-rotatable vane to be rigidly secured in a hub and an outer ring of a rotary machine; and
pre-forming at least one rotatable vane having a radial length less than a radical length of the airfoil, having an axial width less than an axial width of the airfoil, and including a rod extending from the at least one rotatable vane radially outwardly from the outward flank;
then, positioning said preformed non-rotatable vane and at least one rotatable vane in a mold which has an airfoil-shaped cavity having a radial length equal to a distance between the inner and outer flanks of the airfoil to be molded, an axial width to define a leading edge and a trailing edge of the airfoil to be molded, and a thickness which increases from nil at the trailing edge of the airfoil to be molded and decreases to the leading edge thereof;
thereafter, filling the mold with material which is fluent at molding temperature and which is solid and compliant at temperatures of the airfoil's intended use; and
last, removing the airfoil from the mold.
7. A method according to claim 6 further characterized in that:
said at least one rotatable vane is in a position within said airfoil which is closer to the trailing edge of the airfoil than a position of the non-rotatable vane.
8. A method according to claim 6 further characterized in that:
said at least one rotatable vane is in a position within said airfoil which is closer to the leading edge of the airfoil than a position of the non-rotatable vane.
9. A method according to claim 6 further characterized in that:
the step of preforming at least one rotatable vane includes preforming a first rotatable vane with a hollow rod having an inner diameter, and preforming a second rotatable vane with a solid rod having an outer diameter less than the inner diameter of the hollow rod, and the solid rod having a radical length longer than the radial length of the first rotatable vane including the hollow rod; and
the step of positioning said preformed non-rotatable vane and said at least one rotatable vane in a mold comprises positioning the first rotatable vane near the outer flank of the airfoil to be formed and positioning the second rotatable vane near the inner flank of the airfoil to be formed with the solid rod passing through the hollow rod of the first rotatable vane.
10. A method according to claim 6 further characterized in that:
the step of preforming at least one rotatable vane includes preforming a first rotatable vane with a first rod and a second rotatable vane with a second rod which has a radical length longer than the radial length of the first rotatable vane including the first rod; and
the step of positioning said preformed non-rotatable vane and at least one rotatable vane in a mold comprises positioning the first rotatable vane near an outer flank of the airfoil to be formed and positioning the second rotatable vane near an inner flank of the airfoil to be formed with the second rod axially forward of the first rotatable vane.