AIR DE PRÉLÈVEMENT HAUTE-PRESSION REFROIDI MODULÉ POUR ROUE DE COMPRESSEUR CENTRIFUGE

摘要

A gas turbine engine (10) has a cooler (42) to selectively cool during engine high power levels air bled from the high pressure compressor and directed into an impeller rear cavity (30). A bleed airflow passage (36) comprising a bleed-off valve apparatus (34) is connected in fluid communication at one end with the main fluid path of the gas turbine engine at a location upstream of the high pressure compressor and at the other end with the turbine exhaust duct. The cooler (42) has a first passage extending through the cooler and being connected with the compressor bleed-air flow passage (36) in a parallel relationship with the bleed-off valve apparatus (34), and a second passage (46) extending through the cooler and being in fluid communication with the stream of air bled from the high pressure compressor and also with the impeller rear cavity (30) for continuously directing the stream of high pressure bled air through the cooler and into the impeller rear cavity. The bleed-off valve apparatus (34) is modulated to be closed during engine high power levels to create a pressure differential over the bleed-off valve apparatus (34), to drive a stream of low pressure compressor air as a cooling work fluid under such pressure differential to selectively flow through the cooler (42).