Development of a Time-Resolved Pressure Sensitive Paint Technique for Shock Dominated Flows
Abstract
As aerospace systems progress toward increased performance and efficiency, longer service periods and stricter certification processes, the demands on wind tunnel testing and numerical simulations are significantly increased. Wind tunnel pressure models are designed to obtain surface loading for structural design of various components and, locate areas of high-pressure fluctuations, flow transition and separation. A number of time-resolved measurement techniques and associated instrumentation have been developed to perform time series and statistical analysis of unsteady flows. Traditional measurement techniques for acquiring surface pressure distributions on models or flight vehicles have utilized embedded arrays of pressure sensors. An alternative approach to measuring the surface pressure distribution is the use of Pressure-Sensitive Paint (PSP). With this approach, approximately 106 nonintrusive Ôpressure tapsÕ provide sub-millimeter spatial resolution over the entire model surface. The time series data recorded can be analyzed using the same techniques available for traditional pressure measurements. Hence, PSP data has the unique capability to measure pressure with very high spatial resolution and almost at any location on a model regardless of geometry. The proposed instrumentation acquisition focuses on the development of a Fast-PSP system, with a response time up to 10 kHz, which meet the needs of most of our applications. Typical PSP formulations are comprised of an oxygen-sensitive fluorescent dye and a polymer binder for physically attaching the dye to the model surface. The response time of the paint is largely governed by the diffusion rate of gas within the binder. Polymer-based paint has response times on the order of 1 sec, making them unsuitable for unsteady pressure measurements. Although some development in Fast-PSP has been observed in recent years, its applications to date have been limited to simpler problems over a limited range of frequencies. We will collaborate with Innovative Scientific Solutions, Inc., who has recently developed porous binders to enhance oxygen diffusion thus substantially improving temporal response. Fast-PSP will be applied to a number of technically challenging and DoD-relevant problems that involve complex, timedependent, shock dominated flows to gain insight into the critical time-dependent properties. The instrumentation proposed here will lay the groundwork for a dramatic shift in fluid dynamics and flow control research. Fast-PSP system will be integrated with existing low-speed and Polysonic wind tunnel facilities and be an integral part of research, education, and training of students. The primary objective of the proposed instrumentation is to accelerate the use of Fast-PSP to measure unsteady pressures at realistic flow conditions. Fast-PSP will also greatly enhance our ability to educate and train student-scientists and - engineers working on interdisciplinary fluid dynamics problems in multicultural teams. They will become adept in the use of state-of-the-art measurement techniques and complex diagnostics. As we have several on-going collaborations with other institutions, the system will be made available to researchers working on defense related problems within the broader community. As part of our educational outreach, we along with Challenger Learning Center of Tallahassee, organize STEM camps for middle and high school students. The students visit our wind tunnel facilities and participate in the flow visualizations on various aerodynamic configurations. The proposed instrumentation will significantly enhance their experience and motivate them to pursue STEM education.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1710449
Entities
People
- Kumar Rajan
Organizations
- Army Contracting Command
- Florida A&M University
- Office of the Secretary of Defense