Effect of Blade-tip Crossover Passages on Natural-convection Water-cooling of Gas-turbine Blades

A water-cooled turbine was fabricated and tested to determine the effect of a connecting passage at the turbine rotor blade tip between a radial coolant passage 0.10 inch in diameter (length-diameter ratio = 25.5) and radial coolant passages in the legnth-diameter range of 5.1 to 20.4. Coolant flow through the connecting passage is induced by free-convection forces in the radial passages.