Patent ID: 6647708
Filing Date: 2003-11-18
Classification: F02C,F02K,F05D,Y02T

Abstract:
A multi-spool by pass turbofan engine, said engine including:a low pressure spool having a fan at a forward end and a low pressure turbine at an aft end thereof; a high pressure spool coaxially arranged with said low pressure spool and disposed between said fan and said low pressure turbine thereon, said high pressure spool having a high pressure compressor at a forward end disposed rearwardly of said fan on said low pressure spool and a high pressure turbine at an aft end thereof; a combustor in fluid flow communication between said high pressure compressor and said high pressure turbine on said high pressure spool; a combustion gas duct disposed between said high and low pressure spools; a by-pass duct extending from a point aft of said fan on said low pressure spool to a point aft of said low pressure turbine on said low pressure spool, said by-pass duct dividing air flow aft of said fan between said by-pass duct and said high pressure compressor on said high pressure spool; an alternator driven by said high pressure spool; and a sleeve valve in said combustion gas duct aft of said high pressure turbine on said high pressure spool, said sleeve valve being axially movable on a valve support case, said valve support case having an orifice, said orifice disposed between said combustion gas duct and said by-pass duct, said sleeve valve being openable at engine idle conditions, said sleeve valve opening provides a flow path from said high pressure turbine through said orifice to said by-pass duct while minimizing restrictions of said flow exiting said high pressure turbine so as to increase an expansion ratio across said high pressure turbine to produce a relatively high RPM thereof at idle conditions, while concomitantly reducing an expansion ratio across said low pressure turbine to reduce the speed of said low pressure spool and of said fan thereon.