A cooled airfoil ( 10 ) has an internal fluid passage ( 34 ) that includes upstream and downstream legs, such as a co-centrifugal leg ( 40 ) and a counter-centrifugal leg ( 42 ). The legs are separated from each other by a rib ( 44 ) but are connected in series with each other. The airfoil also includes a vent passage ( 56 ) for venting fluid from the internal passage. The intake ( 60 ) to the vent passage resides in the counter-centrifugal leg. The vent at least partially counteracts the separation potential of a separation susceptible region ( 54 ) by allowing some of the coolant to vent from the passage leg ( 42 ).
