Turbojet Engine Noise Reduction with Mixing Nozzle-ejector Combinations
Turbojet Engine Noise Reduction with Mixing Nozzle-ejector Combinations

Author: Willard D. Coles

Publisher:

Published: 1958

Total Pages: 652

ISBN-13:

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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.

NASA Memorandum
NASA Memorandum

Author: United States. National Aeronautics and Space Administration

Publisher:

Published: 1959

Total Pages: 26

ISBN-13:

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The Theory of Diffusion in Strained Systems
The Theory of Diffusion in Strained Systems

Author: Louis A. Girifalco

Publisher:

Published: 1959

Total Pages: 1082

ISBN-13:

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A general theory of solid-state diffusion in strained systems is developed on a molecular-kinetic basis. The theory predicts that for simple strains the diffusion coefficient is an exponential function of the lattice parameter and that the rate of change of the diffusion coefficient with strain is linearly related to the interatomic forces. It has also been shown that for plastic flow the diffusion coefficient is a linear function of strain rate. All the conclusions are confirmed by the data available in the literature.