Accelerated Computed Tomography for Spray Characterization Sandia National Labs

Format:

Book

Conference/Event

Author/Creator:

Yi, Junghwa, author.

Wan, Kevin, author.

Pickett, Lyle, author.

Conference Name:

WCX SAE World Congress Experience (2026-04-14 : Detroit, Michigan, United States)

Language:

English

Subjects (All):

Computed tomography (CT).

Computational fluid dynamics (CFD).

Combustion chambers.

Data acquisition and handling.

Combustion and combustion processes.

Local Subjects:

Computed tomography (CT).

Computational fluid dynamics (CFD).

Combustion chambers.

Data acquisition and handling.

Combustion and combustion processes.

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2026

Summary:

Computed tomography (CT) is a valuable diagnostic technique for visualizing spray plume direction and assessing mixture quality within combustion chambers under engine-relevant conditions. High-speed extinction imaging followed by tomographic reconstruction enables temporally and spatially resolved measurements of liquid volume fraction and plume evolution in multi-plume sprays. Traditionally, tomographic reconstruction requires capturing multiple angular views by rotating the injector and averaging over numerous injections to ensure statistical convergence. This process is time-intensive, particularly due to the large volume of data acquisition and the corresponding delays in data saving, particularly when acquiring many injections per view angle. In this study, we investigate the minimum number of injections required to achieve sufficient CT image quality, thereby significantly reducing experimental time. Two injectors are evaluated: a symmetric 8-hole Spray M injector from the Engine Combustion Network (ECN), and an asymmetric 6-hole injector (THN206) designed for lateral mounting in the cylinder. For Spray M injector, methanol is injected at ambient temperature (20°C) and a backpressure of 0.5 bar. For the asymmetric THN206 injector, the methanol injection is performed at 60°C with a backpressure of 1 bar. In both cases, the injection pressure is 200 bar and 73 different viewing angle are acquired. We analyze how the number of averaged shots influences the convergence of optical thickness and the resulting CT image quality. Key metrics include optical density shot-to-shot variation, centerline profiles and plume direction angles. By comparing these parameters across both injector configurations, we identify an optimized injection count for rapid tomographic imaging. Our results demonstrate that using a two-shot strategy can reduce the total acquisition time by 86% compared to the previous 27-shot averaging approach, while maintaining 3D tomographic image quality sufficient for comparisons to computational fluid dynamic predictions of plume direction, growth, and interaction. These findings highlight the potential for broader and more accessible application of fast CT techniques in spray characterization, without the need for excessive experimental resources

Notes:

Vendor supplied data

Access Restriction:

Restricted for use by site license