Mitigation of under-expanded supersonic jet noise through stepped nozzles

Wei, Xiaofeng; Mariani, Raffaello; Chua, Leok Poh; Lim, H. D.; Lu, Zhenbo; Cui, Yongdong; New, T. H.

doi:10.1016/j.jsv.2019.114875

Cited by 19 publications

(15 citation statements)

References 48 publications

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“…Various researchers have presented computational methods [65,66] with large-eddy simulations [67][68][69][70][71], high fidelity simulations [72] and 3D simulation [73]. The noise reduction of supersonic jets by nozzle trailing-edge changes was investigated experimentally [74], and hemispherical noise reduction reflectors on transonic jet flows [75] were conducted. Different injection sites, angles, and circumstances were also investigated, resulting in distinct acoustic behavior and flow-field changes [76].…”

Section: Noise Controlmentioning

confidence: 99%

A Critical Review of Supersonic Flow Control for High-Speed Applications

2021

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In high-speed fluid dynamics, base pressure controls find many engineering applications, such as in the automobile and defense industries. Several studies have been reported on flow control with sudden expansion duct. Passive control was found to be more beneficial in the last four decades and is used in devices such as cavities, ribs, aerospikes, etc., but these need additional control mechanics and objects to control the flow. Therefore, in the last two decades, the active control method has been used via a microjet controller at the base region of the suddenly expanded duct of the convergent–divergent (CD) nozzle to control the flow, which was found to be a cost-efficient and energy-saving method. Hence, in this paper, a systemic literature review is conducted to investigate the research gap by reviewing the exhaustive work on the active control of high-speed aerodynamic flows from the nozzle as the major focus. Additionally, a basic idea about the nozzle and its configuration is discussed, and the passive control method for the control of flow, jet and noise are represented in order to investigate the existing contributions in supersonic speed applications. A critical review of the last two decades considering the challenges and limitations in this field is expressed. As a contribution, some major and minor gaps are introduced, and we plot the research trends in this field. As a result, this review can serve as guidance and an opportunity for scholars who want to use an active control approach via microjets for supersonic flow problems.

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Section: Noise Controlmentioning

confidence: 99%

A Critical Review of Supersonic Flow Control for High-Speed Applications

2021

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“…These solutions were proposed for the first time by the Lighthill in 1952 [13], and since then, these were studied and developed, and complex geometries resulted. For example, the fluid chevrons [14,15], stepped nozzles [16], and nozzle are manufactured from smart material [17]. As was mentioned before, these solutions were heavily studied, but there are no studies in which the nozzle with chevrons, to be mounted on a turbojet engine, and the performance influences are assessed [18].…”

Section: Introductionmentioning

confidence: 99%

Impact of Using Chevrons Nozzle on the Acoustics and Performances of a Micro Turbojet Engine

Cican

Deaconu

2021

Applied Sciences

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This paper presents a study regarding the noise reduction of the turbojet engine, in particular the jet noise of a micro turbojet engine. The results of the measurement campaign are presented followed by a performances analysis which is based on the measured data by the test bench. Within the tests, beside the baseline nozzle other two nozzles with chevrons were tested and evaluated. First type of nozzle is foreseen with eight triangular chevrons, the length of the chevrons being L = 10 percentages from the equivalent diameter and an immersion angle of I = 0 deg. For the second nozzle the length and the immersion angle were maintained, only the chevrons number were increased at 16. The micro turbojet engine has been tested at four different regimes of speed. The engine performances were monitored by measuring the fuel flow, the temperature in front of the turbine, the intake air flow, the compression ratio, the propulsion force and the temperature before the compressor. In addition, during the testing, the vibrations were measured on axial and radial direction which indicate a normal functioning of the engine during the chevron nozzles testing. Regarding the noise, it was concluded that at low regimes the noise doesn’t presents any reduction when using the chevron nozzles, while at high regimes an overall noise reduction of 2–3 dB(A) was achieved. Regarding the engine performances, a decrease in the temperature in front of the turbine, compression ratio and the intake air and fuel flow was achieved and also a drop of few percent of the propulsion force.

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“…Partially shrouded compressible jet is a type of asymmetric jet (Wlezien and Kibens, 1988) that is encountered in a variety of aerospace applications involving thrust-vectoring (Sutton, 2006), thrust-augmentation (Veen et al, 1974), fluid-mixing (Zeoli and Gu, 2008), and noise suppression (Viswanathan and Czech, 2011). Nozzles exhausting such kind of jets are being researched under various names based on the applications like non-conventional nozzles (Hiley et al, 1976), stepped-nozzles (Wei et al, 2019), plug-nozzles (Romine, 1998), ramp-nozzles (Berry et al, 2017), nozzle with aft deck (Behrouzi et al, 2018) and multi-stream nozzles (Stack and Gaitonde, 2018). In these kinds of nozzle flows, the exhausting jet is partially covered by similar/different fluid streams and partially bounded by a solid-wall.…”

Section: Introductionmentioning

confidence: 99%

“…However, information on other discrete tones at high-frequency in the unsteady spectra is scarcely discussed. Wei et al (2019) report the mitigation of jet noise arising from the under-expanded stepped nozzle. They observe an inconsistent trend in jet noise radiation and broadband shock associated noise (BSAN) about the nozzle pressure ratio variations.…”

Section: Introductionmentioning

confidence: 99%

On the unsteady dynamics of partially shrouded compressible jets

et al. 2021

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We experimentally investigate a partially shrouded sonic jet exiting from a planar nozzle with a solid wall on one side at two different nozzle pressure ratio (ζ = 4 and 5). We experimentally show for the first time that the inherent jet unsteadiness from the shock-induced flow separation on the wall and the emitted noise in the far-field is strongly coupled. The partially shrouded jet's lateral free expansion is also identified to be complicated, three-dimensional, and the produced noise is directional. The emitted acoustic pulses from the flapping-jet, the radiated noise from the shock-induced separation on the wall, and the shock-shear layer interaction on the other side of the wall are responsible for the generated acoustic disturbances. The non-uniform aeroacoustic forcing on the top and bottom portion of the partially wall-bounded jet shear layer leads to a self-sustained jet oscillation and a discrete sound emission.

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Mitigation of under-expanded supersonic jet noise through stepped nozzles

Cited by 19 publications

References 48 publications

A Critical Review of Supersonic Flow Control for High-Speed Applications

A Critical Review of Supersonic Flow Control for High-Speed Applications

Impact of Using Chevrons Nozzle on the Acoustics and Performances of a Micro Turbojet Engine

On the unsteady dynamics of partially shrouded compressible jets

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