Image Number 2 for United States Patent #4306412.
A jet engine having its turbine section and exhaust nozzles particularly arranged to alleviate noise. There is a forward turbine section positioned in a first passageway to receive all or substantially all of the gaseous discharge from the combustion section of the jet engine. There are second and third coannular passageways positioned downstream of the first passageway, with the second passageway being positioned radially inwardly of the third passageway. A second turbine stage is positioned in the second inner passageway to receive a portion of the gaseous flow from the first passageway so as to be driven thereby, with the first portion of gaseous flow being discharged at a relatively low velocity at a radially inward location. A second portion of the gaseous flow passes from the first passageway to the third passageway and is discharged at a relatively high velocity in a generally annular pattern radially outward of the flow of the first portion of the gaseous flow. Thus the gaseous flow is in a velocity profile to alleviate noise from the engine.