This project will complete development of a new sound abatement technology to reduce sound emissions from F/A-18 and EA-18G afterburning turbofan engines (F414-GE-400 and variants). The technology is called Chevron Variable Exhaust Nozzle (CVEN) seals. Chevrons have proven effective in commercial, high bypass non-afterburning, jet engines. Previous results on a F404 engine demonstrated effective reduction in broadband SPLs and 'crackling' noise. F414 chevrons were built and tested on an F/A-18E in 2014. The chevrons demonstrated significant noise reduction on the F404 engine test across the power spectrum, and on the F414 at partial power conditions. The chevron effectiveness on the F414 was found to dissipate at high power levels. Identifying the root cause of this shortfall is critical to implementing noise reduction on the F414 engine, and may lead to new insights that can be applied to future noise reduction programs.
The project will assess the root cause of the 2014 prototype chevron noise reduction shortfall as well as analyze historical results, review scale model data, and complete a derivative parametric study. The result will be used to validate a model capable of making predictions for noise reduction and thrust loss levels for full range of engine operation. The output for this effort will provide technical recommendations for chevron VEN seal changes and a roadmap for effective noise abatement on the F414-GE-400 engine.
If successful, this technology will provide a solution for reducing fighter aircraft engine noise levels for communities and support personnel operating near DoD air installations and in close proximity to aircraft operations. Implementation would provide a cost-effective solution without significant performance impact or redesign of existing engines.
NAVAIR Public Release SPR 2019-22 Distribution Statement A - Approved for public release; distribution is unlimited.