Aerospace Engineering PhD Candidate: Romain Fiévet, Dissertation Chair: Prof. Venkat Raman

In the aerospace world, hypersonic aircrafts have a special place in research due to their transformative potential. The ability to travel at speeds greater than that of sound will vastly alter the global movement of people and goods. At the heart of such hypersonic aircrafts is the dual-mode scramjet engine. Unlike conventional aircraft engines, scramjets lack a moving turbomachinery and instead rely on the natural fluid-mechanical compression of the high-speed ingested air.

The compression stage needs to be carefully designed to provide the combustor with the optimal airflow thermodynamic state, and ensure the target thrust. Since the vehicle’s speed determines the compression ratio, which in turn ensures stable propulsion, a vicious circle can occur if any of these components falters. This leads to a critical in-flight engine shutdown.

The purpose of this dissertation is to decipher by the mean of computational fluid dynamics certain physics inside scramjets. By combining supercomputing resources with state-of-the-art modeling, a high level of detail could be simulated. Particularly, the sensitivity of shock turbulent boundary layer interactions and supersonic combustion to vibrational nonequilibrium was elucidated. In light of these findings, a reduced-order model was built to help design operationally robust engines.

Dissertation Committee Names:
Chair: Venkat Raman
Cognate Member: Eric Johnsen
Members: James F. Driscoll, Mirko Gamba


Publications

List of related peer-reviewed publications

Fiévet, R., Koo, H., Raman, V., Auslender, A., Numerical investigation of shock train response to inflow boundary layer variations, AIAA Journal, Vol. 55, No. 9, 2017. 


Fiévet, R., Voelkel, S., Koo, H., Raman, V. and Varghese, P., Effect of Thermal Nonequilibrium on Ignition in Scramjet Combustors, Proceeding of the Combustion Institute, Vol.36, No. 2, 2017. 


Fiévet, R., Voelkel, S., Varghese, P. and Raman, V., Numerical investigation of vibrational relaxation coupling with turbulent mixing, Journal of Computational Physics (in review). 


Fiévet, R., Raman, V. and Auslender, A., Data-driven one-dimensional modeling of pseudoshocks, AIAA Journal (in review). 


Fiévet, R. and Raman, V., Effect of vibrational nonequilibrium on isolator shock structure, Journal of Propulsion and Power (in review). 

List of related conference proceedings

Fiévet, R., Voelkel, S., Varghese, P. and Raman, V., Numerical investigation of vibrational relaxation coupling with turbulent mixing, 55th AIAA Aerospace Sciences Meeting, AIAA 2017-0663, 2017. 


Reising, H., Haller, T., Clemens, N., Varghese, P., Fiévet, R. and Raman, V., Spontaneous Raman Scattering Temperature Measurements and Large Eddy Simulations of Vibrational Non-equilibrium in High-Speed Jet Flames, AIAA AVIATION Forum, AIAA 2016-3550, 2016. 


Fiévet, R., Raman, V. and Auslender, A., Direct Numerical Simulation of a normal shock train with vibrational nonequilibrium, 69th Annual Meeting of the APS Division of Fluid Dynamics, 2016. 


Fiévet, R., Koo, H., Raman, V., Auslender, A., Numerical simulation of shock trains in a 3D channel, 54th AIAA Aerospace Sciences Meeting, AIAA 2016-1018, 2016. 


Raman, V., Fiévet, R., Clarke, P. and Varghese, P., A Mesoscopic Model for the Description of Small-scale Inhomogeneity in Turbulent Flows with Thermal Nonequilibrium, 68th Annual Meeting of the APS Division of Fluid Dynamics, Volume 59, Number 20, 2015. 


Fiévet, R., Voelkel, S., Koo, H., Varghese, P. and Raman, V., Direct Numerical Simulation of a supersonic reacting jet with thermochemical nonequilibrium, 68th Annual Meeting of the APS Division of Fluid Dynamics, Volume 60, Number 21, 2015.

Fiévet, R., Koo, H. and Raman, V., Numerical simulation of a scramjet isolator with thermodynamic nonequilibrium, 22nd AIAA Computational Fluid Dynamics Conference, AIAA 2015-3418, 2015. 


Fiévet, R., Voelkel, S., Koo, H., Varghese, P. and Raman, V., Numerical Simulation Study of Thermochemical Nonequilibrium Effect on Mixing and Combustion, 67th Annual Meeting of the APS Division of Fluid Dynamics, Volume 59, Number 20, 2014.