Projects per year
Abstract
We propose an approach to predict the modulation of wave packets in shockcontaining jets. With a modeled ideally expanded mean flow as input, an approximation of the shockcell structure is obtained from the parabolized stability equations (PSE) at zero frequency. This solution is then used to define a new shockcontaining mean flow, which is a function of the shockcell wave number at each streamwise station. Linearization of the NavierStokes equations around this quasiperiodic mean flow allows us to postulate a solution based on the Floquet ansatz, and further manipulation of the equations leads to a system called the parabolized Floquet equations [PFE; Ran, Phys. Rev. Fluids 4, 023901 (2019)2469990X10.1103/PhysRevFluids.4.023901] that bears several similarities to PSE. The modulation wave numbers are marched spatially together with the central KelvinHelmholtz wave number, leading to a modulated wave packet as the final solution. The limitations of PFE are highlighted, and the method is applied to two sample cases: a canonical slowly diverging jet at low supersonic Mach number and a heated overexpanded jet, for which largeeddy simulation (LES) data are available. Good agreement is observed between the wave packets predicted by PFE and the leading spectral proper orthogonal decomposition (SPOD) modes from the LES, suggesting that the method is able to capture the underlying physical mechanism associated with wavepacket modulation: the extraction of energy from the mean flow by the KelvinHelmholtz mode and a redistribution of energy to modulation wave numbers due to the interaction of this mode with the shockcell structure.
Original language  English 

Article number  074608 
Number of pages  31 
Journal  Physical Review Fluids 
Volume  7 
Issue number  7 
DOIs  
Publication status  Published  Jul 2022 
Projects
 1 Finished

The art of controlling multijet resonance in jet noise and power generation
EdgingtonMitchell, D., Honnery, D., Samimy, M., Oberleithner, K. & Jordan, P. B.
Australian Research Council (ARC)
26/04/19 → 31/12/22
Project: Research