TURBINE AIRFOIL WITH INTERNAL COOLING SYSTEM HAVING NEARWALL COOLING CHANNELS FORMED FROM AN INNER WALL FORMED SEPARATELY FROM AN OUTER WALL FORMING THE TURBINE AIRFOIL

摘要

An airfoil (10) for a gas turbine engine is disclosed in which the airfoil (10) includes an internal cooling system (14) formed from one or more midchord cooling channels (16) with at least one inner wall (18) positioned within the midchord cooling channel (16) forming a nearwall cooling channel (20). The inner wall (18) may be held in place with an inner wall connection system (22). The inner wall connection system (22) may be configured such that the inner wall (18) can slide spanwise and may have a limited degree of freedom to move towards a pressure or suction side (26, 28), or both. With the inner wall (18) being positioned within the airfoil (10) and not being rigidly connected to the airfoil (10), there exists little, if any, thermal stress between the inner wall (18) and the outer wall (30) forming the airfoil (10). The inner wall (18) may be formed via a bi-cast process in which the inner wall (18) has a higher melting point than the airfoil (10).