04 Feb Hypersonic Jets
Astrophysical Jets: laboratory experiments
Astrophysical Jets: Insight into long term hydrodynamics
Prof. Daniela Tordella, Dip. di Ingegneria Aeronautica e Spaziale, Polytecnico di Torino
Find out more: New Journal of Physics 2011
Online at http://www.njp.org/
doi:10.1088/1367-2630/13/4/043011
The experimental setup. By means of a fast piston mounted on the left, the jet gas is compressed to stagnation pressures ranging from 0.1 to 0.7 MPa , and is accelerated by a de Laval nozzle. The jet travels along a vessel filled with the desired ambient gas (at pressures in the 1.5–100 Pa range) and meets an electron sheet. The sheet ionizes the gases and makes a plane section of the flow visible; these images are acquired by an intensified high-speed CMOS camera.
For more details on experiment please see the New Journal of Physics (2011)
The vessel
Longitudinal section of the piston-nozzle system.
– Jet generation at the nozzle done by Politecnico di Torino for more details please see the Hydrodynamics of hypersonic jets: experiments and numerical simulations
Student Visualization with the electron gun done at Politecnico di Torino
Underexpanded jet, He/Ar: Xenon jet in a Helium medium. Pressure ratio p0 / pamb ~4.3·10^3, Mach before the normal shock ~41,
Reynolds number at the nozzle exit=2.5·10^4
Laboratory experiments done by Philofluid research group at Politecnico Di Torino.
For more details, please see Highly underexpanded jets in the presence of a density jump between an ambient gas and a jet
Underexpanded jet, Ar/He
Laboratory experiments done by Philofluid research group at Politecnico Di Torino.
For more details, please see Highly underexpanded jets in the presence of a density jump between an ambient gas and a jet
Light jet, helium in xenon, M= 16.1. Density maps: numerical simulations and experimental measurements.
– Movie (numerical simulation)
– Movie (experiment)
For more details please see (References: New Journal of Physics 2011 and also NJP Highlights 2011; Astrophysics and Space Science 2011)
Heavy jet, Xenon in air, M= 15. Density maps: numerical simulations and experimental measurements.
– Movie (numerical simulation)
– experimental movies (Xe in Ar): original and reworked by means of multicorrelation techniques.
Light jet, numerical simulation.
t = 15 t_jet
t = 20 t_jet
t = 30 t_jet
t = 40 t_jet
t = 50 t_jet
t = 60 t_jet
Large-eddy simulation of hypersonic jets
Visualizations from a large-Eddy simulations of a compressible with M=5.
The simulation follows the temporal evolution of a initially round 3D jet subject to periodicity conditions along the longitudinal direction. The smagorinsky model has been used together with the selective filtering procedure.
The figure shows the underresolved regions where the small scale indicator f is larger than threshold 0.4.
For more details refer to CPC (2007) and (2013)
Large-eddy simulation of a hypersonic jet at M=5.
The figure shows the under-resolved regions where the small-scale indicator f is larger than the threshold 0.4.
For more details refer to CPC (2007) and (2013)
Large-eddy simulation of a hypersonic jet at M=5.
The blue contours indicate the fraction of space where sub-filter scales are present, and the red lines are the isolines of the streamwise velocity u/u0.