(Georgia Institute of Technology, 2018-06)
Weit, Colby J.; Chetcuti, Steven; Chan, Cherlyn; Muehlberg, Marc; Wei, Lansing; Gilani, Hassan; Schwartz, Katherine G.; Sudol, Alicia M.; Tai, Jimmy C. M.; Mavris, Dimitri N.
In a fiscally constrained environment, it is crucial that both equipment manufacturers and defence invest in technology that shows marked operational improvement. A priori identification of cost-benefit at the early acquisition stage is often limited and incomplete, leading to poor value propositions. This conundrum motivates the need to develop a method to evaluate technologies such as levels of autonomy, stealth capability, improved engines, etc. and make tradeoffs against operational measures of performance and effectiveness (MOP/Es) rather than solely against vehicle performance characteristics. The objective of this study is to create an environment in which those trades against MOEs could be performed rapidly to inform technology investment and acquisition decision-making. This environment is built on top of representative models of a discrete event simulation of disaster relief airlift operations to compare technology modifications or vehicle acquisition options rapidly against operational measures of effectiveness.
(Georgia Institute of Technology, 2018)
Berguin, Steven H.; Renganathan, Sudharshan Ashwin; Ahuja, Jai; Chen, Mengzhen; Tai, Jimmy C. M.; Mavris, Dimitri N.
A sensitivity analysis is performed to quantify the relative impact of perturbing a set of design variables representing an airplane configuration with Over-Wing Nacelles (OWN), operating at transonic cruise. The goal is to study the impact of perturbing the engine's XYZ position and power setting on installation drag, engine inlet pressure recovery, and lift curve characteristics. High- fidelity Reynolds Averaged Navier-Stokes (RANS) simulations of the Common Research Model (CRM) modified with powered, over-wing nacelles are performed and dominant main effects and interactions are identified. The most dominant effect was by far the engine's X position, but it was also found that podded OWN configurations exhibit statistically significant, aero-propulsive coupling. Specifically, certain engine locations cause changes in the flow-field that deteriorate inlet pressure recovery and, vice
versa, a change in engine boundary conditions can affect installation drag. It is therefore recommended to simulate OWN concepts using a coupled MDA or MDAO approach to capture interdependencies between aerodynamics and propulsion.