U.S. Patent Specifications

An axial flow turbojet engine in which the mean direction of flow of working fluid past any moving blade is substantially free from radial components comprising a casing; an air intake in said casing; a low‐pressure axial‐flow compressor mounted in said casing, connected directly to said air intake to receive air through it and having a plurality of rows of moving blades whereof the first row has a hub tip ratio between 0·4 and 0·5; a high‐pressure axial flow compressor mounted in said casing, connected directly to said low‐pressure compressor to receive substantially the whole of the air compressed by said low‐pressure compressor and having a plurality of rows of moving blades; combustion equipment mounted in said casing and connected directly to said high‐pressure compressor to receive substantially the whole of the air compressed by said high‐pressure compressor; a single‐stage axial‐flow high‐pressure turbine mounted in said casing, connected directly to said combustion equipment to receive the products of combustion, and drivingly connected to said high‐pressure compressor, the power developed by said high‐pressure turbine being substantially wholly absorbed by said high‐pressure compressor; and a single‐stage axial‐flow low‐pressure turbine mounted in said casing, connected directly to said high‐pressure turbine to receive the exhaust from it and drivingly connected to said low‐pressure compressor, the power developed by said low‐pressure turbine being substantially wholly absorbed by said low‐pressure compressor; in which engine the ratio of the tip diameter of said low pressure turbine to the tip diameter of said first row of moving blades of said low pressure compressor is between 1 and 1·1; and the ratio between the power absorbed by the high‐pressure compressor and the power absorbed by the low‐pressure compressor is between 2 and 2·5 and the tip diameter of said first row of moving blades of said low pressure compressor is greater than the tip diameter of any other row of moving blades of either of said compressors, and the tip diameter of said low pressure turbine is greater than the tip diameter of said high pressure turbine.