Pressure Sensitive Paint (PSP) Team Successfully Completes First Unsteady PSP Test

QuantiTech personnel supporting the Technical Management and Advisory Services (TMAS) Range contract based out of Tullahoma, TN are working hard to support the mission of the Arnold Engineering Development Complex (AEDC). AEDC is the most advanced and largest complex of flight simulation test facilities in the world, operating more than 68 aerodynamic and propulsion wind tunnels, engine test cells, space environmental chambers, arc heaters, ballistic ranges, and other specialized units. QuantiTech employees provide test tools, services, and engineering expertise to AEDC developmental and operational test communities. 

Recently, QuantiTech personnel on the Pressure Sensitive Paint (PSP) Team completed the first unsteady PSP (uPSP) test for a national priority test customer in the AEDC 16-foot transonic wind tunnel. uPSP is a cutting-edge technique for capturing global surface pressure distributions at frequencies up to 20 kHz using a porous polymer/ceramic oxygen-sensitive paint, high-intensity LED light sources, and high-speed cameras.  Global unsteady pressure distributions, which are spatially and temporally resolved, give engineers unique insight into aerodynamic phenomena like never before.  Numerous applications exist in the aerospace industry, including launch vehicle buffet testing, weapons bay acoustics, inlet-airframe interactions, and more.  Lt. Col. John McShane, Flight Systems CTF Director, thanked the team for their contributions: 

“This analysis tool is not just an evolutionary step in understanding aerodynamic effects; it is possibly revolutionary. When we showed the results to the customer, they were astounded. Each one of them couldn’t believe the data they were seeing and the insight it provides in the development of their system. You did the heavy lifting in getting AEDC and the Nation this capability.  Thank you.” 

Example uPSP result from a prior checkout test: sound pressure level contour of a weapons bay for a modern tactical fighter configuration. (Previously publicly released, AIAA- 2016-1146) 

Images were acquired and processed using custom software developed by the team, and ultimately registered to a 3D CAD model of the wind tunnel model with results captured in both the time and frequency domains.  Data management, transfer, and storage is a challenge in the uPSP realm as each data point can produce as much as 80 gigabytes of data per high-speed camera.  With future projects looking to use as many as eight cameras at a time, a single test could easily produce more than a half petabyte of data for processing and storage.  The team has focused heavily on data acquisition and image processing speeds. Currently, a data point requires 15 minutes per camera to generate final data when processed on an 80-core machine. Advanced post-processing analysis techniques have been implemented to maximize knowledge gained from these data sets, including modal analysis, spatial correlations, coherence, forcing functions, and aero-acoustic analysis. Moving forward, future development efforts will continue to drive down processing time, with the goal being able to view results in near real-time to aid in decision making during air-on testing. 

QuantiTech is proud of our employees Mike Nelson, Craig Morris, Zach Lowry, and Marvin Sellers, for their excellent work supporting the PSP Team and the customer.