JPS57129206A - Steam turbine - Google Patents

Abstract

PURPOSE:To keep the pressure at root section of an exit of a movable vane from becoming higher than that at root section of an inlet of the movable vane at the time of conducting partially loaded operation, by providing a area where the outside wall surface of a casing which forms a flow passage or that of a guide plate has a convex curveture toward the flow passage. CONSTITUTION:A wall surface 12 which is formed by a casing adjoining lower stream side of root section of a movable vane 2 or by a guide plate 11, is composed of the first area 13 which is so formed as to have a convex curveture toward the center section (l) of a flow passage, and also of the second area 14 which is so formed as to be connected to the first area 13 and keep away from the center of the shaft of a turbine further and further toward the lower stream side. Flow at the lower stream side of the root section of the movable vane 2 on thus formed wall surface 12 is to have a convex curveture toward the flow passage center section (l) as shown by a streamline A, and therefore, pressure at root section (m) of an exit of the movable vane 2 is to become smaller than that of the conventional mechanism due to equilibration of force in radial direction.