Abstract: A fluid flow machine has a flow path provided by a casing (1) and a rotating shaft (2), in which rows of rotor blades (3) and stator blades (4) are arranged, and includes at least one annular groove-type recess (5) being disposed in a blade (3, 4) tip area in an annulus duct wall of the casing (1) and/or the shaft (2). An upstream end point (E) of the recess (5) in a flow direction is set at a distance (e)>0 forward of a forward blade tip point (A), and a downstream end point (F) of the recess (5) is set at a distance (f) rearward of point (A), where: 0.5 L>(f)>0, and L is a distance between point (A) and a rearward blade tip point (B).

Abstract: A fluid flow machine has a flow path provided by a casing (1) and a rotating shaft (2), in which rows of rotor blades (3) and stator blades (4) are arranged, and includes at least one annular groove-type recess (5) being disposed in a blade (3, 4) tip area in an annulus duct wall of the casing (1) and/or the shaft (2). An upstream end point (E) of the recess (5) in a flow direction is set at a distance (e)>0 forward of a forward blade tip point (A), and a downstream end point (F) of the recess (5) is set at a distance (f) rearward of point (A), where: 0.5 L>(f)>0, and L is a distance between point (A) and a rearward blade tip point (B).