Abstract: A flow splitter for a gas turbine engine comprising one or more boreholes formed in an exterior surface of the flow splitter. A gas turbine engine comprising a flow splitter.

Abstract: A flow splitter for a gas turbine engine comprising one or more boreholes formed in an exterior surface of the flow splitter. A gas turbine engine comprising a flow splitter.

Abstract: There is disclosed a gas turbine engine comprising a bypass duct defined between a radially inner wall and a radially outer wall. A support radially extends across the bypass duct. The upstream end of the support acts as a source region. A sink region is provided adjacent to and upstream from the source region to at least partly compensate for aerodynamic effects caused by the source region.

Abstract: A method of operating a contra-rotating propeller engine that preferably comprises a 12 bladed front and a 9 bladed rear propeller. As is conventional, the engine is operated during at least a take-off phase, a cruise phase and an approach phase; during the cruise phase the engine operates with a generally constant propeller tip speed. The method is characterised by the step of operating the engine such that the tip speed of either or both of the propellers, during at least one of take-off, climb or approach, at least 10% greater than cruise tip speed. With a specific front to rear propeller spacing, increasing the tip speed reduces overall noise generated by the propellers.

Abstract: Within an intake for a gas turbine engine provision is provided through stator vanes 25, 45 in the stator whereby back pressure from a necessary obstruction 34, 46 can be utilised to balance forward pressure variations caused by intake droop or crosswinds in order to reduce those forward pressure detriments for more efficient engine operation according to a desired objective regime. Typically the flow through the intake 20 is analysed and then an appropriate positioning of the stator vanes 25, 45 determined in order to provide approximate balance between the forward pressures and back pressures. Normally, a combination of camber variation of stator vanes 45a and stagger variation of stator vanes 45b are utilised in order to achieve a desired momentum balance around the circumference of the intake 20. It will be understood that both the forward pressures and the back pressures are differentially variable about the circumference such that one opposes the other.

Abstract: Within an intake for a gas turbine engine provision is provided through stator vanes 25, 45 in the stator whereby back pressure from a necessary obstruction 34, 46 can be utilised to balance forward pressure variations caused by intake droop or crosswinds in order to reduce those forward pressure detriments for more efficient engine operation according to a desired objective regime. Typically the flow through the intake 20 is analysed and then an appropriate positioning of the stator vanes 25, 45 determined in order to provide approximate balance between the forward pressures and back pressures. Normally, a combination of camber variation of stator vanes 45a and stagger variation of stator vanes 45b are utilised in order to achieve a desired momentum balance around the circumference of the intake 20. It will be understood that both the forward pressures and the back pressures are differentially variable about the circumference such that one opposes the other.

Abstract: To reduce the noise levels of open rotor devices rotating at supersonic tip speeds, a combination of blade sweep and aerofoil profile is employed. The sweep of the blade extends through the sonic radius, and in the region of the sonic radius the section comprises a leading edge profile with a rounded nose conforming essentially to the formulaT.about.x.sub.L.sup.a Lwhere T is the blade thicknessx.sub.L is the distance from the front of the leading edgea.sub.L is an algebraic power greater than 3/4 and less than 1.The leading edge profile extends 2-15% of the aerofoil chord and has a nose radius not greater than 2% of the chord. It can be shown that, by these measures, it is possible to moderate the perceived noise levels from a device such as an aircraft propeller rotating at supersonic tip speeds.