Stereoscopic Retroreflective Shadowgraph System for Warhead Characterization
Navy SBIR FY2014.1

Sol No.: Navy SBIR FY2014.1
Topic No.: N141-007
Topic Title: Stereoscopic Retroreflective Shadowgraph System for Warhead Characterization
Proposal No.: N141-007-0926
Firm: Spectral Energies, LLC
5100 Springfield Street
Suite 301
Dayton, Ohio 45431
Contact: Sivaram Gogineni
Phone: (937) 266-9570
Web Site:
Abstract: Spectral Energies, LLC in collaboration with New Mexico Tech proposes to develop a novel stereoscopic retroreflective shadowgraph system for measuring fragment propagation velocities and sizes throughout a large field of view for application to warhead arena or sled testing. Our approach is to use high-speed stereo shadowgraph imaging to identify individual fragments and associated compressible flow phenomena throughout the blast field. The shadowgraph imaging will identify individual fragments and the compressible phenomena (oblique shock waves, compressible-turbulent wakes) associated with the fragment motion. It allows an independent measurement of fragment velocities through the visualization of the oblique shock wave angle, which gives propagation Mach number, and the velocity vector via visualization of the turbulent wake behind the particle. The stereo imaging allows measurement of the three-dimensional position of each fragment, and when combined with high-speed cameras and the shadowgraph technique, it allows velocity measurement. Fragment shape and size will be estimated from the high-speed stereo images.
Benefits: A successful Phase I and Phase I Option for the project will result in the development of a stereoscopic retroreflective shadowgraph system, which is capable of measuring the three-dimensional location, velocity, and size of objects in the field of view. A literature survey indicates that a stereoscopic shadowgraph system has never been developed or attempted, thus a novel measurement system will be developed here with marketing potential for three-dimensional measurements. The explosive testing planned for Phase I will yield preliminary measurements and allow an evaluation of this technique for full-scale measurements. The preliminary testing will be a unique demonstration of this system and will provide data with which the analysis software can be developed. This will be unique stereoscopic imaging data for a fragmenting explosion and the only data that includes stereoscopic refractive imaging. The analysis software to be developed here will allow velocity measurements using a three-dimensional displacement of fragments within the field of view and also via compressible phenomena visualized with the shadowgraph imaging. The system will have two simultaneous methods for determining velocity magnitude and direction, which is unique for any other available measurement techniques. If a custom software package is written, the software will be marketed to individuals measuring three-dimensional fragment propagations and to people performing 3D PIV-type applications. The commercial products foreseen from this SBIR program are a cost-effective 3-dimensional retroreflective shadowgraph system (combined hardware and software), sub-components such as LED light sources, custom-designed image processing software, and custom-designed optics.