Mechanism of Pseudo-shock Wave in Supersonic Jet

Nagai, Minoru

doi:10.1299/jsme1958.26.207

Cited by 16 publications

(4 citation statements)

References 2 publications

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“…12͒. It has been observed in flows with M c as low as 0.75 32 and is believed to be a strong contributor to supersonic jet noise. 33 Mach waves are created because a strong instability propagates at supersonic speed with respect to the ambient air ͑or with respect to the lowspeed stream in a shear layer͒.…”

Section: Discussionmentioning

confidence: 96%

Evolution of large eddies in compressible shear layers

Papamoschou

Bunyajitradulya

1997

Physics of Fluids

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The evolution of large turbulent eddies has been investigated in seven supersonic shear layers with average convective Mach numbers M c ranging from 0.22 to 0.86 and with large variation in density and velocity ratios. A two-laser, single-detector planar laser-induced fluorescence technique was used to visualize the flow and its evolution. Two-dimensional pattern matching yielded the convective velocity of the eddies. For M c Ͼ0.3, fast and slow modes of eddy propagation were detected in supersonic-subsonic and supersonic-supersonic combinations, respectively. An empirical model for the convective velocity is proposed. Plan views reveal coexistence of two-and three-dimensional disturbances. Interaction among eddies appears significantly suppressed. The findings have direct impact on supersonic jet noise and are very relevant to supersonic combustion.

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Section: Discussionmentioning

confidence: 96%

Evolution of large eddies in compressible shear layers

Papamoschou

Bunyajitradulya

1997

Physics of Fluids

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“…From the velocity profiles, halfwidths Y 0.5 and Z 0.5 were calculated. The pitot pressures were measured using a probe of 0.6 mm outer diameter and 0.4 mm inner diameter, designed according to the recommendations of Nagai [15]. The flow field was captured by pitot probe survey using a three way traversing system.…”

Section: Experimental Set-up and Proceduresmentioning

confidence: 99%

Morphology of subsonic rectangular slot jets

Srinivasan

Rathakrishnan

2008

Proceedings of the Institution of Mechanical Engineers, Part G:

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This study is motivated by the fact that studies on compressible subsonic rectangular jets are scarce in the literature. Therefore, experiments have been conducted on rectangular jets of aspect ratios 1, 2, 4, and 6, at Mach 0.4 and 1.0. Another highlight of this study is that slots have been used as jet devices rather than nozzles in order to eliminate azimuthal variations of boundary layer growth in the jet device. The flow is characterized in terms of centreline velocity, jet spread, cross-sectional structure, and entrainment behaviour. Results favour the use of low aspect ratio rectangular jets for mixing enhancement.

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“…In sonic and underexpanded jets, due to the fluctuating nature of the flow field and also due to the fact that the core region of the underexpanded jets is shock-dominated (where a five-hole or a threehole probe cannot be used), only a single hole Pitot probe designed in accordance with the recommendations of Nagai (12) was used. Rice and Raman (13) have noted in their report that, as the flow exiting from their rectangular nozzle was supersonic, it presented considerable measurement problems in using hot wire or hot film anemometry.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 99%

Studies on high speed jets from nozzles with internal grooves

Elangovan

Rathakrishnan

2004

Aeronaut. j.

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Experiments were carried out on jets issuing from circular nozzles with grooved exits and the results compared with those of the plain nozzle. The plain nozzle had an exit diameter of 10mm. Because of the introduction of semi-circular grooves at the exit, the effective or equivalent diameter of the grooved nozzles was 10·44mm. The groove lengths were varied as 3, 5 and 8mm. The nozzles were operated at fully expanded sonic and underexpanded exit conditions. The corresponding fully expanded Mach numbers were 1·0 and 1·41. The shock cell structure of the underexpanded jets from grooved nozzles appeared to be weaker than that of the plain nozzle, as indicated by lesser amplitudes of the cyclic variation of the Pitot pressure. The iso-Mach contours indicate that the jet spread along the grooved plane is significantly higher than that along the ungrooved plane. Off-centre peaks were observed in the mean pressure profile of underexpanded jets from grooved nozzles. They were probably due to the streamwise vortices shed from the grooves.

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Mechanism of Pseudo-shock Wave in Supersonic Jet

Cited by 16 publications

References 2 publications

Evolution of large eddies in compressible shear layers

Evolution of large eddies in compressible shear layers

Morphology of subsonic rectangular slot jets

Studies on high speed jets from nozzles with internal grooves

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