Arc jet Test-Article Surface Recession Rate Monitor

ABSTRACT:Quantitative ablation recession rate measurements of heat shield surfaces are essential for evaluating the performance of heat shield materials. Currently, these measurements are limited to two-dimensional images that focus on the nose tip regression rate. For wedge testing, recession rate is determined by comparing pre- and post-test measurements, and therefore, recession rate as a function of time can only be obtained by conducting separate tests with progressively longer run times. We propose a real-time 3-D surface mapping capability for arc jet models based on the concept of stereo photogrammetric reconstruction of the surface using projected structured light patterns onto the surface.Imaging in this high temperature reactive flow is degraded by emission from the surface and reactions in the flow which result in significant spectral content. Recently, ISSI has demonstrated image-based measurements of particle dynamics in Solid Rocket Motors using narrowband illumination and short exposure times to reject the broadband emission from the flow and surface. The resulting 3-D surface maps of material recession as a function of time would allow more effective ablation performance evaluations of advanced high-temperature materials and enable validation of computational models of material response.BENEFIT:It is noted that the market for ablation coating regression in hypersonic flows is limited, however, the fundamental technology that is key to the proposal, optical surface topography has applications in a variety of industries. A system that provides accurate measurements of surface geometry, even in the presence of noise may be of value aeronautical and bio-medical engineering. For ISSI, the most obvious customer base are existing wind tunnel operators who have an interest in higher performance model deformation systems. The surface-imaging systems that are key to this program could have significant impact on the model deformation applications. ISSI is a key commercial source of PSP technology worldwide, with customers in the US, Japan, Korea, and several countries in the EU. Total sales from this technology are now over $1,000,000 per year with significant growth seen each of the last 6 years. Several commercial customers have expressed interest in model deformation capability. With our current market position, ISSI will be able to market this new capability to existing customers as well as develop new customersts.