Abstract: A turboshaft gas turbine engine comprises, in fluid flow series, a gas-generator compressor, a combustor, a gas-generator turbine, and a free power turbine. The expansion ratios of the turbines are dependent upon an outlet temperature of the combustor, and an expansion relationship between the turbines is defined as the ratio of expansion ratios of the turbines over a running range of non-dimensional power outputs of the gas turbine engine. A second derivative of the expansion relationship is from 0.6 to 1.0.

Abstract: Environmental concerns have resulted in consideration of the effects of condensation trails from gas turbine engines. By provision of a condensation stage in a heat exchanger arrangement for a gas turbine engine the level of condensation within a final exhaust gas flow G from an engine is reduced. Furthermore, by cooling of the exhaust gas flows for mixing with by-pass air flows a water partial pressure at an exhaust gas exit temperature can be provided which is below the eutectic liquid to vapor phase transition and therefore avoid condensation (contrail) formation.

Abstract: A rotor and a stator assembly, wherein the rotor (30) comprises at least one stage of rotor blades (32) and the stator (34) comprises at least one stage of turbine stator vanes (36). The rotor blades (32) have aerofoils and platforms (42) and the turbine stator vanes (36) having aerofoils and platforms (48). A seal (43,45) is defined between the rotor blade (32) platforms (42) and the stator vane (36) platforms (48) wherein a portion (42B) of the rotor blade platforms (42) and/or a portion (48B) of the stator vane (36) platforms (48) comprise a shape memory alloy member or a bimetallic member. The shape memory alloy member, or bimetallic member, controls the flow of cooling air through the seals (43,45) allowing a greater cooling flow at higher temperatures than at lower temperatures.

Abstract: A gas turbine engine turbine comprises an annular array of nozzle guide vanes and an annular array of turbine blades mounted within its annular casing. An array of radially extending protrusions are positioned axially upstream of said array of said nozzle guide vanes and protruding inwardly from the inner casing wall so as to mix the tangential momentum component of the overtip leakage fluid flow before it reaches the array of nozzle guide vanes.

Abstract: A pressure rise combustor is provided with fuel provided at intermittent periods. The fuel is pulsed at timings such that the phase lag between the addition of the fuel and a resultant pressure rise is minimized. The fuel is pulsed such that the unsteady addition of heat reinforces the amplitude of an unsteady pressure fluctuation.

Abstract: A guide vane is adapted to be mounted in an annular fluid-conveying duct of a gas turbine engine, and has an aerofoil part which extends radially across the duct when the guide vane is thus-mounted. On a transverse cross-section relative to the direction of intended fluid flow across the aerofoil part, at least a portion of the aerofoil part is S-shaped.

Abstract: An aerofoil (22,24), preferably of a high lift, highly loaded design, for an axial flow turbo machine (10). The aerofoil having a span, a leading edge (LE), a trailing edge (TE) and a cambered sectional profile comprising a pressure surface (30,72) and a suction surface (28,70) extending between the leading edge (LE) and trailing edge (TE). The aerofoil (22,24) having at least one aerofoil cross bleed passage (36,37,78,80) defined in the aerofoil (22,24) which extends from the pressure surface (30,72) through the aerofoil (22,24) to the suction surface (28,70). The at least one passage (36,37,78,80) preferably disposed generally at a location on the suction surface (28,70) at which boundary layer separation from the suction surface (28,70) would normally occur.