Aerofoil component for a high-pressure or intermediate-pressure turbine

An aerofoil component for a high pressure or intermediate-pressure turbine of a multi-spool gas turbine engine, the component having an aerofoil member which, in use, spans a working gas annulus of the gas turbine engine;

• wherein the aerofoil member has a pressure side aerofoil surface and a suction side aerofoil surface which each extend from a leading edge to a trailing edge of the aerofoil member such that transverse cross sections through the aerofoil member provide respective aerofoil sections, the spacing between the leading edge and the trailing edge on the midspan aerofoil section defining a midspan axial chord length of the aerofoil member, and the aerofoil member being arranged, in use, in a circumferential row around the annulus with plural, equally spaced, identical aerofoil members whereby the circumferential spacing of the aerofoil members at the trailing edges of their midspan aerofoil sections defines a midspan pitch of the aerofoil member;
• and
• wherein the aerofoil member is configured such that at midspan:
• the value of S/Cx is in the range from 1.4 to 1.6;
• and
• the isentropic Mach number on the suction side aerofoil surface of the midspan aerofoil section, calculated by performing CFD analysis at cruise condition of the gas turbine engine, increases from the leading edge to a peak value of Mpeak and then decreases to Mte at the trailing edge, the value of Mpeak/Mte being 1.35 or more and Mte being the time-averaged isentropic Mach number at the trailing edge.