Justin S. Gray
PhD Candidate, Aerospace Engineering

Professor Joaquim R.R.A. Martin
Dissertation Chair

Within a few years of the first jet engine aircraft entering military service, engineers proposed an aeropropulsive concept called boundary layer ingestion (BLI) that could offer reduced aircraft fuel burn.

The jet engine would ingest the boundary layer air and thereby reduce aircraft drag and improve propulsion system efficiency at the same time. Although a promising idea, lack of computational power and aerodynamic analysis tools for viscous flows prevented its adoption.

Thanks to the modern computing power and developments in the field of multidisciplinary design optimization, RANS CFD is now a viable tool for early-stage aircraft design. This has opened the door to the design of BLI propulsion systems.

This thesis presents a detailed aeropropulsive study of the aft-mounted BLI propulsor for NASA's turboelectric STARC-ABL aircraft. The multidisciplinary modeling was performed using a coupled model built with RANS CFD and newly developed 1-D thermodynamic propulsion analysis.

The results of the study show that STARC-ABL could use between 1\% and 4.6\% less energy at cruise compared to a non BLI aircraft. Further results show aerodynamic shape optimization of the aft-fuselage and BLI propulsor nacelle can be used to limit inlet distortion with an associated reduction in BLI performance.

Dissertation Committee:
Chair: Professor Joaquim R. R. A. Martins
Member: Professor James F. Driscoll
Member: Dr. James Heidmann
Cognate: Professor Eric Johnsen


Publications list:

Journal:

J. S. Gray, J. R. R. A. Martins, "Coupled Aeropropulsive Design Optimization of a Boundary Layer Ingestion Propulsor", The Aeronautical Journal, submitted

J. S. Gray, C. A. Mader, G. K. W. Kenway, and J. R. R. A. Martins, “Modeling boundary layer ingestion using a coupled aeropropulsive analysis,” Aiaa journal of aircraft, vol. 55, p. 1191–1199, 2018.

J. S. Gray, J. Chin, T. Hearn, E. Hendricks, T. Lavelle, and J. R. R. A. Martins, “Chemical equilibrium analysis with adjoint derivatives for propulsion cycle analysis,” Journal of propulsion and power, vol. 33, iss. 5, p. 1041–1052, 2017.

Conference:
J. S. Gray, G. K. W. Kenway, C. A. Mader, and J. R. R. A. Martins, “Aeropropulsive design optimization of a turboelectric boundary layer ingestion propulsion,” in 2018 aviation technology, integration, and operations conference, Atlanta, GA, 2018.