Shockinduced noise in supersonic jets

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Shock-induced noise in supersonic jets

• R. Friedrich, J. Sesterhenn, H. Foysi (TUM)
• D. Juvé, Chr. Bailly, Chr. Bogey (ECL)

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MotivationSupersonic jets produce mixing and
shock-associated noise. The latter has high
intensity (screech tones) and leads to structural
fatigue and strong noise pollution.
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What is known?

• Screech (Lele et al. 2000-2003) Shocks are
  reflec-ted at the shear-layer causing upstream
  tra-velling waves which trigger instabilities
  therein.? feedback loop ?tonal noise components

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Objectives-Better understanding of noise
generated by an over-expanded fully turbulent
jet-Reliable noise prediction

• Configuration

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Existing tools/previous work-Compressible
DNS/LES code5th order compact upwind schemes
for conv. terms6th order compact central schemes
for diffusive terms4th order Runge-Kutta time
integration
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Treatment of axis singularity for cyl.
Coord.(Constaninescu and Lele, CTR Research
Briefs 2000)

• Taylor series of flow variables in (r,?)
• For r ? 0 only ?10 and ?10 remain!

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Challenging problems- Generation of inflow
conditions(Fully turbulent supersonic pipe
flow)Results for low Mach number turbulent pipe
flow
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- Treatment of shocks Shock capturing by
explicit filtering (DNS)- Formulation of
adequate boundary conditions Compressible
mixing layer dilatation
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Cooperation

• ECL/TUM Common low Re number flow case for
  comparison of noise prediction by LES and DNS
• TUM/RWTH/IAG Supersonic jet data as input for
  noise propagation studies based on linearized
  Euler eqs.
• TUM/UNI-STRASB./IAG/TUB Comparison between
  subsonic and supersonic jet noise