Turbine blade with internal cooling structure

Abstract

A rotating blade ( 1 ) for a gas turbine comprises an internal cooling structure having at least three cooling air passages ( 5, 6, 7 ) in fluid connection with one another by turns ( 9, 10 ). An opening ( 12 ) provides an outlet for dissolved core material to be removed from the blade following casting of the cooling structure without any residue remaining within. According to the invention, the cooling structure comprises trip strips ( 13, 15 ) in the first and second passage ( 5, 6 ) with specified ratio of height to distance between trip strips and the trip strips ( 13 ) in the first passage being arranged at 90° with respect to the direction of airflow. In a particular embodiment, the trip strips ( 15 ) in the second passage ( 6 ) are arranged at angle of 45°. The design according to the invention assures sufficient airflow through first and second air passages ( 5, 6 ).

1 . A rotating blade ( 1 ) for a gas turbine comprising a blade root ( 2 ), a blade tip ( 3 ) and an internal cooling structure, the internal cooling structure comprising:
 a first cooling air passage ( 5 ) extending generally in the longitudinal direction of the blade from a plenum ( 4 ) in the blade root ( 2 ) to the blade tip ( 3 ),   a second cooling air passage ( 6 ) extending from the blade tip ( 3 ) to the blade root ( 2 ) and a third cooling air passage ( 7 ) extending from the blade root ( 2 ) to the blade tip ( 3 ), the first passage ( 5 ) being in fluid connection with the second passage ( 6 ) by a first turn ( 9 ) and the second passage ( 6 ) being in fluid connection with the third passage ( 7 ) by a second turn ( 10 ), and   an opening ( 12 ) extending from the second turn ( 10 ) to the plenum ( 4 ) providing a direct outlet for fluids from the blade, the first and second cooling air passages ( 5 ,  6 ) each comprising a plurality of trip strips ( 13 ,  15 ), the trip strips ( 13 ) in the first cooling passage ( 5 ) being arranged at an angle (α) of 90°±10° to a direction of cooling fluid flow in the first passage ( 5 ), the trip strips ( 15 ) in the second passage ( 6 ) being arranged at an angle (β) of 45°±10° in relation to the cooling fluid flow direction, and the trip strips ( 13 ,  15 ) in the first and second passages ( 5 ,  6 ) have a height (h) and a distance (d) between adjacent trip strips ( 13 ,  15 ), the ratio between the height (h) and the distance (d) being 10±2.   
   
   
       2 . The rotating blade ( 1 ) according to  claim 1 , wherein the third passage ( 7 ) comprises a plurality of trip strips ( 17 ) arranged at an angle (δ) of 45°±10°.