The Multiscale Interaction of Vibrational Energy Transfer and Turbulent Combustion in Supersonic Flows
Technical Report,30 Sep 2012,29 Sep 2016
University Of Texas At Austin Austin United States
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The project was initiated to try and obtain answers to two basic questions 1 Do non-equilibrium energy distributions affect macroscopic reaction rates2 Can these effects be leveraged for control in design of scramjets The results obtained during the course of this project indicate that both these questions can be answered affirmatively, but the answers were surprising and non-intuitive. Our results have shown that in a co-flow hydrogen jet injector vibrational non-equilibrium delays ignition, but for a highly under-expanded hydrogen jet in a supersonic cross-flow as in the Hyshot configuration vibrational non-equilibrium results in a shorter ignition delay with the flame stabilizing further upstream. This demonstrates that vibrational non-equilibrium can be used to improve flame stability in a suitably designed scramjet. A high speed jet flame facility was designed and constructed. Rayleigh and Raman scattering measurements were made in this flow to obtain non-intrusive temperature measurements. Using a sheet of laser light single shot Rayleigh scattering was used to obtain instantaneous measurements of translational temperature in a plane. The Raman scattering measurements were point measurements and averaged over multiple laser shots to determine independent rotational and vibrational temperatures using high dispersion measurements of Stokes Raman scattering. The Rayleigh measurements were used to determine the probability distribution function pdf of the turbulent fluctuations.
- Combustion and Ignition