Aft loaded airfoil

Abstract

An example airfoil array includes an airfoil array configured to rotate within a turbomachine at a different rotational speed than a fan within the turbomachine. The airfoil array includes a first airfoil that is circumferentially spaced a distance from an adjacent second airfoil. A ratio of the distance to an axial chord length of the first airfoil is less than 1.3. An uncovered turning angle of the first airfoil is greater than 15 degrees.

We claim: 
     
         1 . An airfoil array comprising:
 an airfoil array configured to rotate within a turbomachine at a different rotational speed than a fan within the turbomachine, the airfoil array including a first airfoil that is circumferentially spaced a distance from an adjacent second airfoil, wherein a ratio of the distance to an axial chord length of the first airfoil is less than 1.3, and an uncovered turning angle between the first airfoil and the second airfoil is greater than 15 degrees.   
     
     
         2 . The airfoil assembly of  claim 1 , wherein the turbine airfoil array comprises a low pressure turbine airfoil array. 
     
     
         3 . The airfoil assembly of  claim 1 , wherein the airfoil array is configured to rotate faster than the fan. 
     
     
         4 . The airfoil assembly of  claim 1 , wherein the amount of uncovered turning is the difference between a throat surface angle of the first airfoil and a trailing edge surface angle of the first airfoil. 
     
     
         5 . The airfoil assembly of  claim 1 , wherein the distance is a pitch between the first airfoil and the second airfoil. 
     
     
         6 . A turbomachine arrangement comprising:
 a fan rotatable about an axis;   a turbine section that rotates at a first speed, the turbine section configured to rotatably drive the fan at second, different speed; and   a airfoil array of the turbine section, the airfoil array including a first airfoil that is circumferentially spaced a distance from an adjacent second airfoil, wherein a ratio of the distance to an axial chord length of the first airfoil is less than 1.3, and an uncovered turning angle of the first airfoil is greater than 15 degrees.   
     
     
         7 . The turbomachine arrangement of  claim 6 , wherein the adjacent airfoil is circumferentially adjacent the first airfoil. 
     
     
         8 . The turbomachine arrangement of  claim 6 , wherein the fan and turbine section are components of gas turbine engine. 
     
     
         9 . The turbomachine arrangement of  claim 8 , wherein the gas turbine engine is a geared gas turbine engine. 
     
     
         10 . The turbomachine arrangement of  claim 8 , wherein the turbine section is a low pressure turbine section. 
     
     
         11 . The turbomachine arrangement of  claim 6 , wherein the first speed is greater than the second speed. 
     
     
         12 . A method of establishing a transition location for a turbomachine airfoil comprising:
 positioning a first airfoil relative to a second airfoil within a turbomachine such that a ratio of a circumferential distance between the first airfoil and the second airfoil to an axial chord length of the first airfoil is less than 1.3, wherein the first airfoil has an uncovered turning angle that is greater than 15 degrees and is configured to be rotated about an axis of the turbomachine at a different rotational speed than a fan of the turbomachine.   
     
     
         13 . The method of  claim 12 , wherein the turbomachine is a geared gas turbine engine. 
     
     
         14 . The method of  claim 12 , wherein the circumferential distance is a pitch. 
     
     
         15 . The method of  claim 12 , wherein the first airfoil is configured to be rotated about the axis of the turbomachine at a greater rotational speed than the fan of the turbomachine.