Volume 17, Issue 2 (2017)                   Modares Mechanical Engineering 2017, 17(2): 359-368 | Back to browse issues page


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Bahman Jahromi I, Ghorbanian K, Ebrahimi M. Experimental Study of the Noise Sources from a Hot Supersonic Jet Impinging on a Flat Plate at Initial Stages of Jet Formation. Modares Mechanical Engineering. 2017; 17 (2) :359-368
URL: http://mme.modares.ac.ir/article-15-7230-en.html
Abstract:   (1980 Views)
The far-field acoustic signature of this transient impinging jet is experimentally investigated in this study. Feedback loop mechanism which is an acoustic resonance mode generated by the reflection of jet shear layer noise from the impinging plate and affecting jet mixing shear layer, is also investigated. The stagnation temperature of jet is increased by means of a reflected type shock tube up to 950 (K). A convergent-divergent nozzle generates jet with Mach number of 1.4. The far-field mixing layer noise of this quasi-steady free jet is compared by the results of steady state generated ones. The acoustic signal of this transient jet is investigated when impinges to a normal plate. It is seen that every specific phenomenon has its most powerful acoustic signature at a distinct angle relative to the impingement point. The time-frequency investigations by the means of wavelet transform and related scalograms reveal that the sound wave generated by feedback loop mechanism is tonal and continuous in time compared to the acoustic signals of the jet shear layer that are seen as the intermittent acoustic events in the far-field acoustic scalograms.
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Article Type: Research Article | Subject: Gas Dynamics
Received: 2017/01/7 | Accepted: 2017/01/21 | Published: 2017/02/19

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