Jet noise reduction using co-axial swirl flow with curved vanes

Balakrishnan, P.; Srinivasan, K.

doi:10.1016/j.apacoust.2017.05.009

Cited by 21 publications

(5 citation statements)

References 26 publications

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“…One of the objectives of the early experimental studies on jet noise was to find ways to reduce the intensity of the noise that was radiated, while maintaining nozzle performance (i.e., jet thrust) by making use of knowledge about the characteristics of the sources of noise generation in the turbulent mixing region of a jet. There are numerous studies and research initiatives addressing jet noise reduction [5,6]. Here we revisit some of these jet noise reduction techniques.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

Cican,

Gall,

Bogoi

et al. 2023

Inventions

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In connection with subsonic jet noise production, especially regarding the hot jet from a micro turbojet engine, we encountered a lack of recent high-resolution data in the literature describing the flow field using experimental validation through optical diagnoses. The objective of this paper is to examine and compare the influence on shear layers of the exhaust plug nozzle of a micro turbojet engine with and without chevrons mounted, using a high-speed camera used in Schlieren-type optical system diagnosis. Three different operating regimes are examined for both the baseline configuration and the configuration with 16 triangular-shaped chevrons. In conjunction with the image captures, the sound pressure level was recorded with the help of a microphone placed perpendicular to the flow, 0.4 m from the exhaust of the nozzle which was further processed. In quantitative terms, we found that the OASPL decreases by more than 1% when the engine is operating at higher regimes. Moreover, we found that the average exhaust jet angle, which is a measure of the quality of the fluid mixing layer is increased by 5% with respect to the baseline nozzle. By using the “darkest pixel” technique in Schlieren imaging, we can verify experimentally, for all working regimes, the theory that asserts that subsonic jet noise is a consequence of fine-scale homogeneous turbulence. Additionally, the potential novelty lies in the specific observations related to consistent dispersion of fine-scale eddies and how the presence of chevrons amplifies this uniformity within the turbulent field.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

Cican,

Gall,

Bogoi

et al. 2023

Inventions

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“…Broadband shock-associated noise is one of the main components of supersonic jets and most noise sources are distributed at the interaction between shock and turbulence (Shen et al , 2021). Compared with the vortex jet, the swirling jet can eliminate the transonic noise (Balakrishnan and Srinivasan, 2017a, 2017b). The shock wave structure produced by the stepped nozzle is very irregular, and the jet plume is deflected significantly.…”

Section: Introductionmentioning

confidence: 99%

Research on jet noise characteristics of aeroengine double S-bend nozzles with different cross sections

Shao

Zheng

et al. 2022

HFF

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Purpose This study aims to improve the survivability and maneuverability of the fighter,and study the stealth performance of fighter in the jet noise of aeroengine, it is of great significance to study the jet noise characteristics of double S-bend nozzles. Design/methodology/approach The multiparameter coupling and super-ellipse design methods are used to design the cross section of double S-bend nozzle. Taking unsteady flow information as the equivalent sound source, the noise signal at the far-field monitoring points were calculated with Ffowcs Williams–Hawkings (FW–H) method, and then, the sound source characteristics of the double S-bend nozzle are analyzed. Findings The results show that the internal flow of the S-bend nozzle with rectangular section is smoothed and the aerodynamic performance is better than super-ellipse section, the shear layer length of rectangular section is longer, the thickness is smaller and the mixing ability is stronger. The sound pressure level of the two S-bend nozzles decreases with the increase of the monitoring angle, and the sound pressure on the horizontal plane is greater than the vertical plane. In the direction of 40°–120°, the jet noise of rectangular nozzle is smaller, and the multiparameter coupled rectangular cross section structure is more applicable. Practical implications It is beneficial to reduce the jet noise of the engine tail nozzle and improve the stealth performance of the aircraft. Originality/value There is very little research on the jet noise characteristics of the double S-bend nozzle. The multiparameter coupling and the super-ellipse method are used to design the nozzle flow section to study the aerodynamic performance and jet noise characteristics of the double S-bend nozzle and to improve the acoustic stealth characteristics of the aircraft.

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“…Swirls introduced into a multiphase separator would contribute to strong centrifugal forces that can separate solid particles from solid-fluid mixtures [4]. Balakrishnan and Srinivasan [5] suggested that generating swirling flow is an effective way of reducing noise in subsonic free jets.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Analysis of Flow Behavior for Reverse Circulation Drill Bit with Inserted Swirl Vanes

Yang¹,

Jiang²,

et al. 2022

Geofluids

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A swirling drill bit designed with an integrated vane swirler was developed to improve reverse circulation in down-the-hole hammer drilling. Its entrainment effect and influential factors were investigated by CFD simulation and experimental tests. The numerical results exhibit reasonable agreement with the experimental data, with a maximum error of 13.68%. In addition, the structural parameters of the swirler were shown to have an important effect on the reverse circulation performance of the drill bit, including the helical angle and number of spiral blades, swirler outlet area, and the flushing nozzles. The optimal parameters for the swirling drill bit without flushing nozzles include a helical angle of 60°, four spiral blades, and the area ratio of 2, while it is about 30°, 3, and 3 for the drill bit with flushing nozzles. Moreover, the entrainment ratio of the drill bit without flushing nozzles can be improved by nearly two times compared with one with flushing nozzles under the same conditions.

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Jet noise reduction using co-axial swirl flow with curved vanes

Cited by 21 publications

References 26 publications

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

Experimental Investigation of a Micro Turbojet Engine Chevrons Nozzle by Means of the Schlieren Technique

Research on jet noise characteristics of aeroengine double S-bend nozzles with different cross sections

Experimental and Numerical Analysis of Flow Behavior for Reverse Circulation Drill Bit with Inserted Swirl Vanes

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