This Small Business Innovation Research Program (SBIR) Phase I project will evaluate the feasibility of utilizing a low-resolution X-Ray tomography system in tandem with a coded aperture scheme to obtain highly resolved profiles of deep holes. Three tasks are planned during the Phase I work: The first is to design and integrate a transmission grating with a low resolution X-Ray tomography system to obtain high-resolution X-ray radiographs at multiple view angles. The second is to develop an algorithm to deconvolute these high-resolution radiographs to provide spatially resolved local density information at sub-micron scales. The third is to evaluate the system using an automotive GDI injector. During the Phase I work, the feasibility of obtaining very high resolution profiles of deep holes such as those in automotive injectors will be completely demonstrated. During the Phase II, a prototype system that can be used by automotive and aerospace industry will be developed and evaluated. The intellectual merit of the proposed project is that it provides a sound and novel approach for utilizing advanced state-of-the-art X-ray instrumentation in conjunction with robust deconvolution methods for obtaining precise profile measurements inside narrow deep holes.
The broader impact/commercial potential of this project is two-folds. The first involves the estimation of fuel injector geometry in automotive injectors. New Corporate Average Fuel Economy standards mandate much higher efficiency from automotive engines than are currently possible. All automotive manufacturers are actively pursuing Gasoline Direct Injection with precise control of the spray shape and duration to achieve higher efficiency over a broad spectrum of operating condition. One of the key instrumentation need within the industry is a diagnostic to accurately map the profile of the injector holes. The proposed system will be the first instrument that can provide this unmet need with sufficient ease and accuracy for routine use by injector manufacturers. The second application is in the aerospace industry. In the aerospace industry, hundred percent testing of nozzles is mandatory. One of the issues facing the industry is the need to accurately profile the geometry of the nozzle holes, so as to ensure that relevant performance criteria for the nozzle can be met. The commercial and societal benefit of the proposed project is that it will enable industry to measure relevant information inside fuel injectors and nozzles, enabling higher efficiency and reduced pollution emission.
This Small Business Innovation Research Phase 1 project evaluated the feasibility of utilizing a low-resolution X-Ray tomography system in tandem with a coded aperture scheme to obtain highly resolved profiles of deep holes. Three tasks were planned during the Phase I work: The first was to design and integrate a transmission grating with a low resolution X-Ray tomography system to obtain high-resolution X-ray radiographs at multiple view angles. The second was to develop an inversion algorithm to deconvolute these high-resolution radiographs to provide spatially resolved local density information at high resolution scales. The third was to evaluate the system using sample objects. During the project, En’Urga Inc. built the coded aperture system. Data was collected from three different objects, namely a 25 micron slit, a 100 micron slit, and a 150 micron pin. When the transmission grating was inserted into the X-Ray path, the signal to noise ratio of the system dropped from 100 to less than four or five. Therefore, it was very difficult to get good radiograph images for successful tomographic inversion. However, even with the limited SNR, the 100 micron slit and 150 micron pin were imaged with high accuracy. When the 25 micron slit was image, the SNR was so low it was not easy to ascertain the full success of the scheme. Based on the Phase I work, feasibility of the system was completely demonstrated. However, the SNR of the system has to be improved during the Phase II work to achieved sub 5-micron resolution.
