INCREASING COMPRESSION EFFICIENCY VIA SHAFT POWER TRANSFER

In a gas turbine engine 101 of the type having a high-pressure (HP) spool and a low-pressure (LP) spool, methods of increasing surge margin and compression efficiency at a given thrust are provided. One method increases compression efficiency and comprises transferring mechanical power from the HP spool to the LP spool to reduce a corrected speed of a HP compressor 105 therein and raise a working line of a LP compressor 104 therein. Another method increases surge margin and comprises transferring mechanical power from the LP spool to the HP spool to increase a corrected speed of a HP compressor 105 therein and lower a working line of a LP compressor 104 therein.