Abstract: This invention relates to hot film shear stress sensors and their fabrication. We describe a hot film shear stress sensor comprising a silicon substrate supporting a membrane having a cavity underneath, said membrane bearing a film of metal and having electrical contacts for heating said film, and wherein said membrane comprises a silicon oxide membrane, where in said metal comprises aluminium or tungsten, and wherein said membrane has a protective layer of a silicon-based material over said film of metal. In preferred embodiments the sensor is fabricated by a CMOS process and the metal comprises aluminium or tungsten.

Abstract: This invention relates to hot film shear stress sensors and their fabrication. We describe a hot film shear stress sensor comprising a silicon substrate supporting a membrane having a cavity underneath, said membrane bearing a film of metal and having electrical contacts for heating said film, and wherein said membrane comprises a silicon oxide membrane, where in said metal comprises aluminium or tungsten, and wherein said membrane has a protective layer of a silicon-based material over said film of metal. In preferred embodiments the sensor is fabricated by a CMOS process and the metal comprises aluminium or tungsten.

Abstract: A transition duct for a gas turbine engine typically contains one or more non-turning fairings. These fairings disturb the air flow through the duct, leading to flow separation and aerodynamic inefficiency. The invention proposes non-axisymmetric perturbations in the duct end walls to minimise these undesirable aerodynamic effects. This permits the construction of shorter and lighter transition ducts, with more pronounced curvature.

Abstract: An aerofoil (34) for a gas turbine engine is substantially solid, including a concave pressure surface (42) and a convex suction surface (40). The pressure surface (42) is provided with a projection in the form of an elongate fin (44) which extends in the radial direction of the aerofoil.

Abstract: An aerofoil (34) for a gas turbine engine is substantially solid, including a concave pressure surface (42) and a convex suction surface (40). The pressure surface (42) is provided with a projection in the form of an elongate fin (44) which extends in the radial direction of the aerofoil.

Abstract: To reduce profile losses in the aerofoils of low pressure turbines of axial flow reaction turbines, the wake-passing effects on a row of aerofoils downstream of a first row of aerofoils are enhanced by providing a region of roughness on part of the suction surface of each aerofoil of the downstream row. The region of roughness has its leading edge between the location of the geometric throat on the suction surface and a location 75% of the surface perimeter from the leading edge. The region extends over at least 3% of the suction surface perimeter. The use of such a region of roughness is particularly effective in improving the performance of very high-lift aerofoils (coefficient of lift of 1.1 or greater).