Two Arnold Engineering Development Complex analysts specializing in computational fluid dynamics recently provided insight on how technology has been beneficial to their areas of expertise during a technical excellence seminar held at Arnold Air Force Base, Tenn.
Jason Klepper, CFD analyst who has worked at AEDC for 18 years, presented on the dynamic inlet simulation demonstration for airframe-propulsion integration.
“An aircraft inlet system captures airflow and delivers it to an engine at the appropriate Mach number for that system,” he said. “To meet design constraints, modern fighter aircraft have complex inlets with multiple turns that generally lead to both total pressure and swirl distortion at the engine face.”
Klepper mentioned flow distortions can lead to reduced system performance, operability and durability introducing issues in the overall success of the weapon system performing the mission.
“The integration of the airframe, inlet and propulsion system is a key design issue in the development of military aircraft,” he said. “High Performance Computing Modernization Program’s CREATE™-AV Kestrel tools have been demonstrated to accurately model inlet dynamic distortions in a sub-scale airframe and inlet system for a current military aircraft.”
CREATE™, short for Computational Research and Engineering for Acquisition Tools and Environments, is a software that provides production-quality design and analysis.
Milt Davis, AEDC technology transition manager, described Klepper’s efforts as “ground-breaking computational work.”
“The solutions he is producing require an enormous amount of computational power because he is analyzing highly dynamic events associated with flow eddy structures that we have not been able to do before,” he said. “The codes of today are being developed to provide dynamic analysis capability and the analyst have to understand what they are producing. Both of these aspects are driving the ability to analyze inlet flow distortion that has been unattainable before.”
Following Klepper’s informative discussion, AEDC analyst Stephen Guimond presented on the CFD analysis of the AEDC Propulsion Wind Tunnel 16-foot transonic wind tunnel C1 compressor, providing information on how CREATE™-AV Kestrel tools have been used to support the rotor re-blading effort by generating time accurate, full annulus simulations covering various points on the compressor map.
“Due to the complex geometries and length scales found in turbomachines, it is difficult to measure detailed internal flow field information without influencing the fluid mechanics,” he said. “A CFD simulation supplements measured data to provide detailed flow field characteristics within the turbomachine to support design requirements generation.”
Time-averaged and transient rotor static pressure distributions have since been extracted from the simulations and are being supplied to a structural analyst for further investigation.
Greg Power, AEDC engineer specializing in modeling and simulation, commended both Klepper and Guimond on the work that they do and explained how advantageous it is to the test customer.
“Klepper’s work on the F-35 inlet dynamics demonstrates the significant benefit of performing CFD simulations to plan ground and flight tests and analyze test data to provide the maximum knowledge at the lowest cost from a test campaign,” Power said. “Stephen’s work on the 16T compressor blades demonstrates the ability to determine design requirements well before any hardware is built to ensure that the final product performs as expected while minimizing risk.”