Identification and Active Control of Jet Noise Sources Using High Resolution Coupled Measurement Devices and Methods

The noise due to jet engine exhausts of current military and commercial aircraft continues to be a major environmental concern since the advent of jet aircraft. Challenges associated with increasing levels of noise pollution include aircraft operations ashore and afloat. The high frequency, intense noise, and associated vibration pose physical and environments hazards to air crews, ground support personnel, and those residing or working in the vicinity of active aviation operations. In order to identify and mitigate the jet noise sources, Spectral Energies, LLC in collaboration with Syracuse University (SU), The Ohio State University (OSU), and United Technologies Research Center (UTRC) propose to develop experimental diagnostic methods that will establish the cause-effect linkage between the jet turbulent velocity field, the associated unsteady pressure in the jet, and the resulting near field and far field acoustic pressures. The diagnostic instrumentation will provide sufficient temporal and spatial resolution to identify the jet noise sources within this sequence of flow-noise generation. Tasks to be conducted in the SU anechoic chamber demonstrating the source diagnostic system consist of: 1) setting up high speed cold jet experiments at Mach 0.6 and incorporating a high speed high resolution PIV system, 2) acquiring high speed high resolution PIV measurements simultaneously with near and far field acoustic pressures in the baseline jet configuration, 3) acquiring high speed high resolution PIV measurements simultaneously with near and far field acoustic pressures in the controlled jet (excitation frequencies/amplitudes will be guided by results from step 1 and 2), and 4) performing POD analysis on velocity fields and cross correlate with the near and far field acoustic pressures. The knowledge gained from Phase I will be used to evaluate flow control methods for jet noise reduction and for establishing data analysis methods for pressure and turbulence data acquisition during Phase II. Higher Mach numbers and nozzle geometries approaching military engine configurations are planned for Phase II. This research will have significant impact on civilian and military gas turbine engines and land based gas turbine power generation units. BENEFIT: The knowledge gained from the proposed research will help identifying the jet noise sources and methods to control them. The proposed research will also have significant impact on civilian and military gas turbine engines and land based gas turbine power generation units.