Gas turbine engine with heat exchanger in annular duct

A gas turbine engine is provided having a turbine and a rotor assembly driven by the turbine and operable during high power operating conditions at a first blade pass frequency (f1) of greater than or equal to 2,500 Hz and less than or equal to 5,000 Hz; a heat exchanger positioned within the annular duct and extending substantially continuously in the circumferential direction, where the effective transmission loss (ETL) of the heat exchanger positioned within the annular duct is between 5 decibels and 1 decibels for high power operating conditions, and where the heat exchanger comprises a heat transfer section defining an acoustic length (Li), and wherein the operating acoustic reduction ratio (OARR) is greater than or equal to 0.75 to achieve ETL under high power operating conditions, the OARR being equal to: # imgabs0 # wherein during the high power operating conditions a1 is equal to 13,200 inches per second. 提供了一种燃气涡轮发动机，具有：涡轮机和转子组件，转子组件由涡轮机驱动并且能够在高功率操作条件期间以大于或等于2,500赫兹且小于或等于5,000赫兹的第一叶片通过频率(f1)操作；热交换器，