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Abstract <p>Experimental investigations are carried out with triangular shaped tabs orientated circumferentially 120° apart with designed nozzle Mach numbers of 1.5, 2.0, and 2.5. The effects of the Mach number with a constant exit pressure ratio (EPR) of 0.35 and the constant nozzle pressure ratio (NPR) of 6 are studied. The Pitot survey and Schlieren flow visualization are carried out to present the jet core length characteristics, the shock cell structure, and the jet spread through time-averaged images. Acoustic measurements are made inside an anechoic chamber to get the signatures of various nozzle design Mach numbers. It is observed that the screech fundamental frequency shifts with increase in the design Mach numbers. The triangular shaped tabs can reduce the jet core length effectively to the tune of 40–70% in the ranges tested at various designed Mach numbers. The results indicate complete alleviation of noise/acoustics for jets adopting tabs having triangle shape irrespective of the penetration depth and orientation.</p>

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Influence of the Mach Number on the Flow Field and Acoustics of a Supersonic Jet with Tabs

  • 期刊论文

  • 发表日期：

    2025年2月1日

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  • S. R. Lavala,
  • S. Das

摘要

Abstract

Experimental investigations are carried out with triangular shaped tabs orientated circumferentially 120° apart with designed nozzle Mach numbers of 1.5, 2.0, and 2.5. The effects of the Mach number with a constant exit pressure ratio (EPR) of 0.35 and the constant nozzle pressure ratio (NPR) of 6 are studied. The Pitot survey and Schlieren flow visualization are carried out to present the jet core length characteristics, the shock cell structure, and the jet spread through time-averaged images. Acoustic measurements are made inside an anechoic chamber to get the signatures of various nozzle design Mach numbers. It is observed that the screech fundamental frequency shifts with increase in the design Mach numbers. The triangular shaped tabs can reduce the jet core length effectively to the tune of 40–70% in the ranges tested at various designed Mach numbers. The results indicate complete alleviation of noise/acoustics for jets adopting tabs having triangle shape irrespective of the penetration depth and orientation.