The supersonic reacting jet was designed to study the effects of vibrational energy exchange in supersonic mixing and combustion. The jet is Mach 1.5 and issues into a slow co-flow of heated air. The jet is non-reacting when operated with nitrogen or air, and it combusts when operated with hydrogen fuel in the jet stream.
The facility is shown in the figures below. The facility was built by former PhD student, Heath Reising, in collaboration with Prof. Philip Varghese. The co-flow is supplied by a blower, which forces air through a HEPA filter (square section) before passing through two 30 kW electrical-resistance heaters. After heating the air passes into the 12-inch diameter co-flow section, where it is conditioned using a perforated plate and fine-mesh screen. The supersonic nozzle is axisymmetric and located at the center of the co-flow section. The jet exit diameter is 6 mm. The jet fluid is supplied by high-pressure cylinders and can be an inert gas such as air or nitrogen, or a fuel such as hydrogen.
Schematic diagram of the Supersonic Jet Facility.
Photograph of the Supersonic Jet Facility showing co-flow heaters (bottom), co-flow section middle and supersonic nozzle (top)
The facility was designed to investigate the effect of vibrational non-equilibrium on high-speed jet flames. Non-equilibrium is induced by mixing of the cold jet fluid with the hot (1000 K) co-flow gas. A schlieren image showing a subsonic jet issuing into the heated co-flow is shown below. The co-flow is revealed by the strong density gradients associated with the co-flow-to-room-air shear layers surrounding the co-flow section.
Schlieren images of the facility in operation: (left, top) subsonic jet issuing into the heated co-flow; (right, bottom) supersonic jet
The facility was used to conduct measurements of vibrational non-equilibrium with spontaneous Raman scattering. Raman scattering was performed using a single laser-bream as shown in the photograph below.
Nd:YAG laser focused in the shear-layer of the supersonic jet was used for spontaneous Raman scattering of N2.
More information about this facility can be found in the following paper:
Reising, H.H., KC, U., Clemens, N.T. and Varghese, P.V., “Measurement of mixing-induced thermal non-equilibrium in a supersonic shear layer using spontaneous Raman scattering,” Physics of Fluids, Vol. 29, 076101 (11 pages), 2017