Abstract: A turbofan engine includes a core engine, a fan, a fan bypass duct partially surrounding the core engine and the fan, and a bleed system. The bleed system includes a first bleed circuit configured to bleed pressurized air from the core engine and channel the flow to a first circuit of a heat exchanger, and a second bleed circuit configured to bleed fan air from the fan bypass duct and channel the flow to a second circuit of the heat exchanger. The second bleed circuit includes a bleed duct including a duct inlet and a duct outlet coupled in flow communication with the heat exchanger through a valve. The bleed duct also includes an acoustic suppression conduit extending from the bleed duct upstream of the valve to the fan bypass duct and sized to suppress pressure oscillations inside the second bleed circuit when the valve is at least partially closed.

Abstract: A turbofan engine includes a core engine, a fan, a fan bypass duct partially surrounding the core engine and the fan, and a bleed system. The bleed system includes a first bleed circuit configured to bleed pressurized air from the core engine and channel the flow to a first circuit of a heat exchanger, and a second bleed circuit configured to bleed fan air from the fan bypass duct and channel the flow to a second circuit of the heat exchanger. The second bleed circuit includes a bleed duct including a duct inlet and a duct outlet coupled in flow communication with the heat exchanger through a valve. The bleed duct also includes an acoustic suppression conduit extending from the bleed duct upstream of the valve to the fan bypass duct and sized to suppress pressure oscillations inside the second bleed circuit when the valve is at least partially closed.