The New Jersey Institute of Technology's
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Title:	Blast shock-wave characterization in experimental shock tubes
Author:	Kahali, Sudeepto
View Online:	njit-etd2020-104 (xv, 130 pages ~ 6.5 MB pdf)
Department:	Department of Mechanical and Industrial Engineering
Degree:	Doctor of Philosophy
Program:	Mechanical Engineering
Document Type:	Dissertation
Advisory Committee:	Chandra, N. (Committee co-chair) Ji, Zhiming (Committee co-chair) Datta, Dibakar (Committee member) Lee, Eon Soo (Committee member) Roman, Max (Committee member)
Date:	2020-12
Keywords:	Finite element analysis Flow field Shock waves Simulation and modelling Traumatic brain injury Wave diffraction
Availability:	Unrestricted
Abstract:	Blast-induced traumatic brain injuries have affected U.S. soldiers deployed for extended periods in the gulf and Afghanistan wars. To identify the biomechanical and biochemical mechanisms of injury, critical in the identification of diagnostic and therapeutic tools, compressed gas-driven shock tubes are used by investigators to study shockwave-animal specimen interactions and its biological consequences. However, shock tubes are designed and operated in a variety of geometry with a range of process parameters, and the quality of shock wave characteristics relevant to field conditions and therefore the study of blast-induced traumatic brain injuries suffered by soldiers is affected by those conditions. Lab-to-lab comparison is restricted by these variations, inhibiting data pooling and impeding progress. Shock waves accurately characterized by a validated numerical model can be effective in identifying the relationship between shock characteristics vis-à-vis specific shock tube. In this work, a finite element model was developed and validated with data from carefully designed experiments. It was hypothesized that the shock wave characteristics are governed by the energy source, geometry of the tube and specimen location, both along the length and within the section. Using three specific aims, it was identified that a truncated finite element model is appropriate. It was also shown, while the shock wave replicated the field parameters inside the shock tube, the characteristics outside the tube was complex and as affected by vortex tube and jet winds. Therefore, it was determined that this location may not be suitable for replication relevant to the mild TBI problem. It was also determined that shape, size, and location of occlusion increases with the ratio of obstruction to shock tube cross-section.