Abstract: In a turbomachine having stationary and rotating bladed stages, the blades of the rotating bladed stage are cooled by ducting cooling fluid into an interior cavity formed in each blade. Each rotating blade has a tip portion which is closely adjacent an annular shroud to avoid hot gas products bypassing the blades. The required close clearance between the blade tips and the annular shroud has caused manufacturers to provide a recessed blade tip cap and an open plenum at the blade tip to improve cooling flow. This invention minimizes the height requirements of sidewalls to the open plenum by providing an opening in the blade sidewalls whereby cooling air can be discharged from the interior blade cavity and the blade plenum without regard to the clearance between the blade tip and the annular shroud.