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Flow Control for Supersonic Mixing Enhancement and Jet Noise Reduction
Başlık:
Flow Control for Supersonic Mixing Enhancement and Jet Noise Reduction
Yazar:
Pourhashem, Hamideh, author.
ISBN:
9780355981926
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (153 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Sunil Kumar; Iraj M.Kalkhoran Committee members: Kurt Becker; Vittoria Flamini; Iraj Kalkhoran; Sunil Kumar; Maurizio Porfiri; Iskender Sahin; Richard Thorsen.
Özet:
Enhancement of high speed jet mixing has practical implications in the operational environment of supersonic aircraft such as reducing the noise radiation from the high-speed jet engines and promoting the supersonic combustion efficiency in scramjet engines. There have been various flow control methods developed in the past with varying degrees of applicability and complexity for mixing enhancement of subsonic and supersonic compressible fluid streams. However, there are certain challenges associated with the intrinsically low mixing rate of supersonic flows, which pose limitations on the application of the flow control methods. Numerical investigations are conducted in the present research to expand upon previous experimental work, with the aim of establishing a deeper understanding of the mechanisms of mixing enhancement in supersonic flows and the physics of the flow responsible for the supersonic mixing. More specifically, flow control methods such as downstream microjet fluidic injection and shock/vortex interaction methods, are developed and examined in order to promote both fine-scale and large-scale mixing in supersonic flows, aiming at jet noise reduction from jet engines and improving the combustion efficiency of the of scramjet engines.
As part of this research work, downstream microjet fluidic injection method is utilized as a flow control method in order to enhance the supersonic jet mixing from jet engines and suppress the jet noise radiation. The fluidic injection method which is used in this study is a Downstream Microjet Fluidic Injection (DMFI) system. This method utilizes a downstream 90 degrees point injection, in an attempt to effectively target the regions of the jet plume which possess higher potential for mixing enhancement. This approach allows for an effective control of the turbulence and the associated noise radiation from the convecting large turbulence scales compared to the other methods of flow control, where mostly the finest scales were targeted. DMFI system is bound to alter the stability characteristics of the jet shear layer due to the well-known characteristics of transverse flow injection, including generation of streamwise vortices, as well as the upstream separating bow shock. These are some of the features which affect the mixing characteristics of the jet shear layer, and hence the mixing component of supersonic jet noise. Furthermore, DMFI alters the shock cell structure, and thus affects both the screech and broadband shock associated noise. All of these contribute to the supersonic jet noise reduction.
Another aspect of supersonic mixing enhancement, which has been investigated in this thesis focuses on the possibility of using shock/vortex interaction for supersonic mixing enhancement such as increasing the combustion efficiency of the scramjet engines. In hypersonic flights, the combustor Mach number remains supersonic and transverse mixing is inhibited. Such flow situations with high velocities and short residence times require that fuel and air mix and burn quickly to avoid excessively long combustors in order to improve the engine performance. As part of this research, various aspects of shock wave/vortex interactions were explored, where the specific case of shock wave generated during a sonic injection into a supersonic cross flow was considered. The first part of this study was concentrated on investigating the characteristics of the transverse injection of a sonic jet into a supersonic crossflow at various operating conditions, and the second part involved generation of an experimentally validated streamwise vortex and examining its interaction with the bow shock produced due to the transverse flow injection. Through this study, the potential advantage of supersonic vortex bursting in enhancing fuel air mixing at supersonic Mach numbers was demonstrated. Furthermore, it was shown that the supersonic vortex bursting results in redistribution and increase of vorticity in the flow field, which enhances the entrainment and mixing of injectant and supersonic crossflow.
Notlar:
School code: 1988
Tüzel Kişi Ek Girişi:
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(678249.1) | 678249-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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