Abstract: The present invention relates to a valve including a valve member co-operating with a seat provided with a crenellated portion disposed around the portion of the seat on which the valve member rests, said crenellated portion being constituted by teeth separated by gaps, the inside walls of the teeth being portions of a vertical axis cylinder, the width l of the gaps being less than the width b of the inside walls of the teeth, wherein the end wall of the valve member facing the crenellated portion when the valve member is in its closed position is convex in shape, co-operating with the inside wall of each tooth to form a channel that flares from top to bottom of the tooth, the point of contact C between the valve member and the seat being at a distance d from the base B of the crenellated portion lying in the range 0.25 times to 0.5 times the width l of the gap. Vibrations are eliminated at partial load and pressure fluctuations downstream from the valve are reduced.

Abstract: A blade array for turbomachines comprises blades disposed between an inner wall and an outer wall. The inner wall and/or the outer wall is provided with a suction port near at least some blades. This port has a first end situated along the upper surface in a region of the blade extending from the point of maximum curvature to the neck of the passage between said blade and the adjacent blade. The port enabling the efficiency to be increased is oriented along an isobar line. Its length is such that the second end is spaced from the upper surface of the blade by a distance between one quarter and one half the width of the neck of the inter-blade passage.

Abstract: A valve comprises a valve obturator cooperating with a valve seat provided with crenellations disposed around the part of the valve seat on which the valve obturator rests. Each crenellation comprises on its surface facing the valve obturator a vertical central partition between two symmetrical openings.