A COMPUTATIONAL STUDY OF CONTOURED PLUG-NOZZLE JET NOISE

✍ Scribed by I.S. Das; A. Khavaran; E.A. Krejsa

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 456 KB
• Volume: 206
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1997.1038

✦ Synopsis

A computational noise study of a scale model of an axisymmetric ideally contoured plug-nozzle (CPN) is presented. The CPN has an exit diameter of 45 mm and the geometrical configuration is such that the jet flow is shockless at the design pressure ratio, jd = 3•62. The gas dynamics of the jet flows has been predicted using the NPARC Computational Fluid Dynamics code with the k-o turbulence model. The gas dynamics data are then used to perform the noise computations based on the modified General Electric MGB code. The study covers a range of pressure ratios, 2•0 E j E 5•0. The agreement of the computational aeroacoustic results with the reported experimental data is favorable. At the design pressure ratio (shockless flow), the predicted noise levels are within 3 dB. At the off-design pressure ratios (flows with shocks), the theory predicts the noise levels within 5 dB, except at very high frequencies for pressure ratios farthest from the design pressure ratio when deviations up to 8 dB are noted. The computed directivity patterns do not represent the reported experimental trends well. The mechanism of shock formation in the CPN jet flows is noted to be basically different from those in the convergent nozzle and convergent-divergent nozzle jet flows. The computational results indicate consistent noise reduction effectiveness of the CPN relative to the equivalent convergent and convergent-divergent nozzles for all operating pressure ratios.