Reducing jet noise using resolvent-based sensitivities*

To increase community acceptance of forthcoming supersonic civilian jet transports, we develop a resolvent-based technique to reduce the take-off radiated noise from their low-bypass-ratio turbofan engines with near-sonic exit velocities.  Linear resolvents are shown to be sensitive to the jet exhaust properties and to the exhaust nozzle design.  A method to directly connect changes in the resolvent to changes in the exhaust properties and the nozzle design and is developed and demonstrated on dual stream near-sonic jets that have been tested experimentally.  Both cold and heated jets are considered.  The presentation will include the details of the resolvent-based method, its application to RANS-predicted jet mean flows, noise reduction estimates compared to experimental measurements, and conclude with integration details into a nozzle design optimization process.