Turbojet Engine Noise Reduction with Mixing Nozzle-ejector Combinations

Download or read book Turbojet Engine Noise Reduction with Mixing Nozzle-ejector Combinations written by Willard D. Coles and published by . This book was released on 1958 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several noise suppressors consisting of combinations of mixing nozzles and ejectors were tested on two full-scale turbojet engines. Maximum sound pressure level reductions of 12 decibels and sound power level reductions of 8 decibels were obtained. The ejectors provided 3 to 5 decibels of the sound power reduction. The effects of ejector dimensions on noise suppression and engine performance were investigated. Ejector lengths of approximately 2.0 standard nozzle diameters and ejector diameters larger than 1.6 standard nozzle diameters provided the greatest additional noise reduction to that obtained with the mixing nozzles alone. The ejector can restore the static thrust loss caused by use of the mixing nozzle or can provide static-thrust augmentation.