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

ABSTRACT: 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. 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) developed and implemented a high resolution diagnostic method and acquired velocity field simultaneously with near and far-field pressure data. POD and wavelet analyses of this data helped in establishing 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. Preliminary investigation on flow control was also evaluated during Phase I program. Based on the progress made during Phase I, the research team proposes the following technical objectives during Phase II: 1) develop and demonstrate the prototype high resolution coupled measurement device and methods from phase I; 2) establish and exhibit a methodology for the analysis of coupled pressure and turbulence data; and 3) develop new concepts for the reduction of jet noise. This research will have significant impact on civilian and military gas turbine engines and land based gas turbine power generation units. BENEFIT: The proposed research effort will provide new diagnostic capabilities, computational tools and methodologies for identifying the jet noise sources and methods to control them and also for analyzing pressure and turbulence data. This research will facilitate the characterization of noise suppression devices (e.g. plasma actuators, synthetic jet actuators, microjets), associated hardware and software that will enable the government (e.g. Air force, Navy, NASA) and aircraft engine (GE Aviation, Pratt & Whitney) and airframe manufacturers (Boeing Corp. and Lockheed Martin) to address the challenges associated with gas turbine engine and jet noise. These tools are critical for increasing the acceptance rate and long-term health of engines and airframes for the warfighter. The proposed research will help to validate numerical models and to identify and validate control strategies. Such experimental and numerical tools will also lay the foundation for similar tools that would be valuable in the analysis of commercial gas-turbine combustors, internal combustion engines, and stationary power generation systems.