Measurement of shock structure and shock–vortex interaction in                     underexpanded jets using Rayleigh scattering

J. Panda; R. G. Seasholtz

doi:10.1063/1.870247

Measurement of shock structure and shock–vortex interaction in underexpanded jets using Rayleigh scattering

Physics of Fluids ◽

10.1063/1.870247 ◽

1999 ◽

Vol 11 (12) ◽

pp. 3761-3777 ◽

Cited By ~ 97

Author(s):

J. Panda ◽

R. G. Seasholtz

Keyword(s):

Rayleigh Scattering ◽

Shock Structure ◽

Vortex Interaction ◽

Underexpanded Jets

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Effect of Mach number on the acoustic field of 2:1 elliptic-slot jet

The Aeronautical Journal ◽

10.1017/s0001924000095932 ◽

2001 ◽

Vol 105 (1043) ◽

pp. 9-16 ◽

Cited By ~ 5

Author(s):

S. B. Verma ◽

E. Rathakrishnan

Keyword(s):

Mach Number ◽

Fundamental Frequency ◽

Acoustic Field ◽

Major Axis ◽

Shock Structure ◽

Minor Axis ◽

Noise Levels ◽

Underexpanded Jets ◽

Barrel Shock ◽

Mach Numbers

Abstract The shock-structure and the related acoustic field of underexpanded jets undergoes significant changes as the Mach number Mj is increased. The present investigation is carried out to study the effect of Mach number on an underexpanded 2:1 elliptic-slot jet. Experimental data are presented for fully expanded Mach numbers ranging from 1.3 to 2.0. It is observed that the ‘cross-over’ point at the end of the first cell at low Mach numbers gets replaced by a normal shock at a highly underexpanded condition resulting in the formation of a ‘barrel’ shock along the minor-axis side with a ‘bulb’ shock formed along the major-axis side. The above change in shock structure is accompanied by a related change in the acoustic field. The amplitude of fundamental frequency along the minor-axis side grows with Mj but falls beyond Mj = 1.75. Along the major-axis side, however, the fundamental frequency does not exist at low Mach numbers. It appears at Mj = 1.75 but then falls at Mj = 2.0. The related azimuthal directivity of overall noise levels (OASPL) shows significant changes with Mj.

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Influence of Sweep on the 3D Shock Structure in an Axial Transonic Compressor

Volume 6: Turbo Expo 2005, Parts A and B ◽

10.1115/gt2005-68835 ◽

2005 ◽

Cited By ~ 6

Author(s):

Jo¨rg Bergner ◽

Stephan Kablitz ◽

Dietmar K. Hennecke ◽

Harald Passrucker ◽

Erich Steinhardt

Keyword(s):

Beneficial Effect ◽

Experimental Analysis ◽

Shock Structure ◽

Operating Conditions ◽

Vortex Interaction ◽

Tip Leakage Vortex ◽

Stall Margin ◽

Tip Leakage ◽

Transonic Compressor ◽

Design Speed

To improve the understanding of how sweep affects the 3D shock structure and the shock-vortex interaction, two transonic compressor bladings are measured with a 3D Laser-2-Focus setup, and the flow is analyzed for comparable operating conditions. Rotor 1 features radially stacked profiles, while rotor 3 introduces forward sweep. Performance comparisons of these rotors [1] indicated that forward sweep, as introduced in this design, has a beneficial effect on performance and stall margin. The detailed experimental analysis of the 3D shock structure and the influence of tip leakage vortex interaction at design speed is the scope of this paper.

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Effect of Co-Flow on Near Field Shock Structure

Journal of Fluids Engineering ◽

10.1115/1.4006911 ◽

2012 ◽

Vol 134 (7) ◽

Cited By ~ 5

Author(s):

T. Srinivasarao ◽

P. Lovaraju ◽

E. Rathakrishnan

Keyword(s):

Near Field ◽

Shock Structure ◽

Experimental Results ◽

Underexpanded Jets ◽

Core Length ◽

Central Nozzle ◽

Supersonic Core Length ◽

Expansion Level

This paper presents the experimental results of underexpanded jets delivered from a central nozzle surrounded by a co-flow. The co-flow is found to be effective in elongating the supersonic core length of the central jet, at all levels of underexpansion. However, the expansion level of the central jet dictates the elongation caused by the co-flow.

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