국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Jet Noise Scaling in Dual Stream Nozzles
저자	Khavaran, Abbas;; Bridges, James
Keyword	AERODYNAMIC NOISE;; BYPASS RATIO;; HIGH FREQUENCIES;; JET AIRCRAFT NOISE;; LAWS;; NOISE GENERATORS;; SPECTRA;; TEMPERATURE RATIO
URL	http://hdl.handle.net/2060/20110000527
보고서번호	NASA/TM-2010-216887
발행년도	2010
출처	NTRS (NASA Technical Report Server)
ABSTRACT	Power spectral laws in dual stream jets are studied by considering such flows a superposition of appropriate single-stream coaxial jets. Noise generation in each mixing region is modeled using spectral power laws developed earlier for single stream jets as a function of jet temperature and observer angle. Similarity arguments indicate that jet noise in dual stream nozzles may be considered as a composite of four single stream jets representing primary/secondary, secondary/ambient, transition, and fully mixed zones. Frequency filter are designed to highlight spectral contribution from each jet. Predictions are provided at an area ratio of 2.0bypass ratio from 0.80 to 3.40, and are compared with measurements within a wide range of velocity and temperature ratios. These models suggest that the low frequency noise in unheated jets is dominated by the fully mixed region at all velocity ratios, while the high frequency noise is dominated by the secondary when the velocity ratio is larger than 0.80. Transition and fully mixed jets equally dominate the low frequency noise in heated jets. At velocity ratios less than 0.50, the high frequency noise from primary/bypass becomes a significant contributing factor similar to that in the secondary/ambient jet.