Turbine blade passive clearance control

An internally air cooled airfoil of a turbine blade used in a gas turbine engine having internal passageway adjacent the pressure side of the airfoil and independent internal passageway adjacent the suction side of said airfoil,

• said airfoil having a tip section, an annular shroud surrounding said tip section and defining therewith a gap that changes its radial dimension resulting from the radial positioning of said annular shroud and said tip section relative to each other, the improvement comprising:
• means for obtaining a momentum flow stream in opposition to the flow of engine fluid medium flowing through said gap, said means including at least a pair of intersecting installed passages formed into the tip of said airfoil in proximity to the intersection of the tip surface with the pressure side of said airfoil for discharging air from said internally cooled airfoil, whereby the resultant flow resulting from the momentum and direction of the flow occasioned by the velocity and direction of the flow discharging through said intersecting installed holes provides an aerodynamic seal in said gap to minimize the leakage of engine working medium flowing over the working surfaces of said airfoil.