Abstract: An annulus filler of a gas turbine engine includes an outer lid including a leading edge, a trailing edge, a first longitudinal edge, a second longitudinal edge, and an outer radial surface. The outer radial surface includes a first nominal surface portion and a second nominal surface portion. The outer radial surface further includes a protruding surface portion extending radially outwardly from each of the first nominal surface portion and the second nominal surface portion and a recessed surface portion extending radially inwardly from each of the first nominal surface portion and the second nominal surface portion. Each of the protruding surface portion and the recessed surface portion is configured to redirect an air drawn through the gas turbine engine.

Abstract: An aerofoil for a compressor comprising a suction surface and a pressure surface with a thickness distribution defined therebetween, the aerofoil further comprising a first local maximum in the thickness distribution and a second local maximum in the thickness distribution, the second local maximum being downstream of the first local maximum and the second local maxima being formed by a first region of concave curvature in the suction surface between the first and second local maxima, wherein the second local maximum is disposed such that in use a boundary layer upstream of the second local maximum on the suction surface is thinned by the second local maximum, and in addition the boundary layer may be sufficiently thinned so that an interaction of an upstream flow feature with the thinned boundary layer is capable of generating a turbulent spot with a calmed region downstream of the turbulent spot.

Abstract: An aerofoil (52) for a compressor comprising a suction surface (56) and a pressure surface (58) with a thickness distribution defined therebetween, the aerofoil further comprising a first local maximum in the thickness distribution and a second local maximum (54) in the thickness distribution, the second local maximum (54) being downstream of the first local maximum and the second local maxima being formed by a first region of concave curvature in the suction surface between the first and second local maxima, wherein the second local maximum is disposed such that in use a boundary layer upstream of the second local maximum on the suction surface is thinned by the second local maximum, and in addition the boundary layer may be sufficiently thinned so that an interaction of an upstream flow feature with the thinned boundary layer is capable of generating a turbulent spot with a calmed region downstream of the turbulent spot.