Hypersonic Ground-Test Flow Field Response Surface Methodology

The United States Air Force (USAF) uses a robust test and evaluation (T&E) process to understand the performance, operability, and durability of new or modified flight systems. A significant fraction of the T&E data is obtained in ground-test facilities such as those located at the Arnold Engineering and Development Center (AEDC) in Tennessee. These and other facilities play a crucial role in reducing the risks of fielding a weapon system as it progresses through the development process. One of the major challenges in operating a ground-test facility in support of the USAF T&E mission is to provide a test environment that adequately simulates a known flight environment. This need to understand the relationship between the facility test environment and the desired flight environment has led AEDC to invest significant resources in the development of intrusive diagnostic probes and analytical tools to understand and communicate data analysis results. The engineering staff at AEDC’s Aerodynamic and Propulsion Test Unit (APTU), a supersonic freejet test facility scaled for ramjet and scramjet missile systems, has recently coupled these two investments in order to better define and understand the APTU flow field produced by existing freejet nozzles. This paper will highlight recent test operations and discuss how the statistical methods commonly referred to as Design of Experiments (DOE) were used to define a conceptual measurement system to improve both the fidelity and efficiency of flow field characterization. The benefits of using DOE for this conceptual definition were verified experimentally through a simple analysis of alternatives study.