By Simon Mendez & Mohammed Shoeybi
Supersonic jet noise is a problem of great importance. To better understand this phenomenon, we simulated both hot and cold supersonic jet flows shown in the following movies.
Compressible large-eddy simulation using a dynamic model and the flagship CTR code CharLES was used. The flow inside the nozzle is laminar, which develops into turbulent flow at the nozzle exit. A great deal of interesting work on generating the proper meshes for this complex multi-physics phenomenon were also considered. There are many other interesting aspects of this work.
Observe the shock train produced by the high pressure gas inside the nozzle rapidly accelerating upon exiting into the atmosphere. Large-scale motions and fine-scale turbulence are present, both of which contribute to turbulence and the radiated noise. One goal of this work is to understand which processes dominate the sound radiated to the far-field. The scattered sound field due to the shock strain and shock-turbulence interactions are also present.
The above two movies show the cold jet flow case. Observe that the upstream noise is not nearly as strong in this case since the jet is perfectly-matched.