Unstructured Meshing for Computational Fluid Dynamics Analysis of Hybrid Wing Body Aircraft
Michael W. Barton
Mississippi State University, NASA Glenn Space Academy 2011
Meng-Sing Liou, Ph.D.
NASA Glenn Research Center, Cleveland, Ohio, 44135
Unstructured volume meshes were created for the N+2B baseline, a part of the National Aeronautics and Space Administration’s Fundamental Aeronautics Program. The Fundamental Aeronautics Program develops tools and technologies for the future of American aviation. The N+2B vehicle, which is scheduled to be transferred to industry at TRL 6 in 2020, features a hybrid wing body airframe shape and nine embedded jet engines using boundary layer ingestion. Using multiple software packages, existing geometry was cleaned and refined, and then unstructured volume meshes were generated. The meshes were optimized for computational efficiency and are only to be used for initial analysis. As analysis continues in the future, the flow over the hybrid wing body will be analyzed for flight performance and boundary layer ingestion optimization.
When the average American thinks of the National Aeronautics and Space Administration (NASA), only the “space” portion comes to mind. After all, NASA sent men to the moon and built a space station! In reality, researchers at NASA are constantly working on new innovations in all kinds of fields outside of space, especially in aeronautics. NASA’s Fundamental Aeronautics Program (FAP) program tasks NASA researchers and contractors to come up with next-generation aircraft and technologies that will reduce the impact of aviation on the environment. This is especially important when one considers that the American air transportation industry is expected to double in the next twenty years.
FAP is unique in that it demands simultaneous improvement in the fields of community noise, nitrous oxide (NOx) emissions, and fuel efficiency. The FAP program is broken up into three smaller project development lines, referred to as N+1, N+2, and N+3. N+1 is the short-term program that expects technologies that can benefit current single-aisle aircraft by 2015. The goals for N+1 include a -32 dB noise reduction over current FAA Stage 4 certification, 60% reduction in NOx emissions, and 33% reduction in fuel consumption. N+2 is the mid-term program that blends feasible technology improvements and a new hybrid wing body fuselage shape. N+2 aims at bringing the industry a -42 dB noise reduction, 75% reduction in NOx emissions, and 40% reduction in fuel consumption by 2025. N+3 represents the long-term possibilities of next-generation aircraft (~2035) and aims to produce a -71 dB noise reduction, a better than 75% reduction in NOx emissions, and a better than 70% reduction in fuel consumption.
The Aeropropulsion Division (RT) at NASA Glenn Research Center is currently working on the N+2 program. For the N+2 effort, an integrated solution involving, airframe advancements, jet engine technology improvements, and vehicle systems integration is considered to be a viable way to achieve all three lofty goals. There are two configurations being tested: the N+2A configuration is a hybrid wing body has twin engines mounted above the airframe, while the N+2B configuration is an embedded engine version of the same aircraft.
My role in the FAP program will be flow investigation of the N+2B configuration using computational fluid dynamics (CFD). The flow over any aircraft is important, as successful analysis and design optimization can lead to reduced skin friction and a more efficient vehicle. The flow over the N+2B is especially important because of the embedded engines, which will use boundary layer ingestion to improve fuel efficiency.
To complete this objective, I will:
- Become familiar with NASA-developed CFD codes and software systems.
- Complete any unfinished volume grid generation of the N+2B model.
- Compute the flow over the N+2B configuration using geometries produced by previous NASA interns.
- Perform an aerodynamic analysis using NASA’s CFD tools on NASA’s supercomputer.
I intend to learn all I can about CFD and NASA’s systems during my short time here, but the ultimate goal is to provide data analysis to NASA that would aid in design optimization of the N+2B configuration.
 Collier, Fayette. “Overview of NASA’s Environmentally Responsible Aviation (ERA) Project,” 48th AIAA Aerospace Sciences Meeting. January 4, 2010.