Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session T31: Shock Waves and Explosions |
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Chair: Matei Radulescu, University of Ottawa Room: 255 C |
Monday, November 25, 2024 4:45PM - 4:58PM |
T31.00001: Shock Interaction with a Large-Amplitude Sinusoidal Perturbation on a Fast-Slow(F/S) Gaseous Interface Xinyu Xie, Michael J Wadas, Ziyang Huang, William Joseph White, Eric Johnsen Shock Wave refraction on a perturbed density interface causes dilatation of interface perturbations, and deposition of baroclinic vorticity. On an F/S interface, a large interface perturbation could lead to transition from a regular refraction (i.e., the incident, reflected and transmitted shock has triple point on interface) to an irregular Mach reflection refraction pattern. Correct modelling of these early time interactions is of fundamental importance to supersonic mixing problems such as scramjet injectors and ICF fuel capsule designs. The objective of our study is to develop a model for interface morphology and circulation deposition during the whole interaction phase. As a model for curved interface, we consider a series of slanted planar interfaces and employ shock wave refraction theory and shock polar method to predict transition between different regimes and to solve the flow field of refraction patterns. We also study the structure and hysteresis of the Mach Reflection Refraction (MRR) system on a curved interface in detail. Our model, grounded in analytical techniques in gas dynamics, is then verified by comparison to high-order-accurate numerical simulations |
Monday, November 25, 2024 4:58PM - 5:11PM |
T31.00002: Shock tracking in unsteady, reacting flows using the method of characteristics Christopher G Veatch, Thomas Ward Using the method of characteristics, a 1-dimensional model has been developed to examine unsteady, reacting flow properties in the subsonic, transonic, and supersonic regions with second order accuracy. A four-equation Euler model with a superelliptic approach to temperature variation, previously explored by Reinbacher and Regele (2017) is being utilized with a one-step hydrogen-air combustion reaction to examine the flow’s local Mach number, pressure, and temperature as the combustion advances in time. The method of characteristics allows us to determine the location and time where a shock appears in the 1-D flow and subsequently track its propagation through the flow. By adjusting dimensionless parameters that include the Damkohler number and dimensionless reaction enthalpy within the model as well as maximum temperature and initial fuel concentration, the formation of the shock can be tracked in time and space. Our initial results show agreement between this low order method when compared to CFD results that appear in the literature. |
Monday, November 25, 2024 5:11PM - 5:24PM |
T31.00003: Direct Numerical Simulations of Interactions between Spherical Shock Wave and Homogeneous Isotropic Turbulence Kento Tanaka, Taisei Watanabe, Hiroki Suzuki, Toshinori Kouchi Shock waves in the real world often propagate in free space with radial curvature. This study aims to clarify the characteristic changes of such shock waves caused by the interaction with turbulence. For this purpose, direct numerical simulations of the interaction between a spherical shock wave and homogeneous isotropic turbulence are carried out. The first analysis is about the deformation of the shock wave. The local positions of the shock wave were defined as the position of the maximum pressure, and its variation was taken as the deformation. The results show that the deformation monotonically increases, which differs from the case of the planar shock wave. Next, the ratio of the local pressure increase to the average pressure increase was defined to investigate the variation of the pressure increase. The ratio increases with propagation as well as the deformation. Thus, it was found that the pressure increase varies with the interaction and that the intensity of the variation grows as well as the deformation. Finally, to investigate the relationship between the deformation and the pressure increase, we computed the pressure distribution conditioned on whether the local shock wave position is in front of or behind the mean position. The results showed that when the shock wave was behind the mean position, the overpressure was higher, and vice versa. This behavior is similarly observed in the planar shock wave. |
Monday, November 25, 2024 5:24PM - 5:37PM |
T31.00004: Self-similar shock dynamics satisfying the inviscid Burgers equation in planar, cylindrical and spherical problems Matei Radulescu The solution of self-similar shock dynamics satisfying the inviscid Burgers equation are provided in closed form for planar, cylindrical and spherical problems. The approach follows Lee's method for obtaining self-similar solutions for the Euler equations describing compressible fluid dynamics. Closed form solutions are provided for the two types of self-similar solutions: of the first kind, where the shock dynamics are constrained by integral relations, and the second kind, constrained by the internal requirement of the regularity of solutions along limiting characteristics. The solutions obtained illustrate simply the theoretical underpinning of Taylor-Sedov blast waves (self-similarity of the first kind) and Guderley implosion problems (self-similarity of the second kind). |
Monday, November 25, 2024 5:37PM - 5:50PM |
T31.00005: Analysis and Prediction of Soot Morphology in Post-Detonation Fireballs Tahir Latif Farrukh, Michael Omana, Sivaramakrishnan Balachandar, Adam Hammond-Clements How soot evolves and disperses in detonation-like conditions is not well understood, despite the importance of soot morphology and dispersion on radiative and mass transport. To model soot formation and transport, a simulation framework was compiled using several different models to simulate the explosive flow and particle formation and development. For the flow, CTH, a Sandia hydrocode that has multi-material simulation capability, was used to model the detonation and early-time gas dynamics of a canonical hemispherical explosive charge. Subsequently, simulation is handed off to HyBurn, an in-house code at the University of Florida that excels at modeling instability growth [1], wherein later-time hydrodynamics are computed. In parallel, particle size distribution predictions are made by modeling coagulation and aggregation in Lagrangian-tracked parcels of fluid with the commercial code ANSYS Chemkin Pro. Custom collision kernels were also examined to observe the impact on particle agglomeration. Comparison to observation highlights persisting gaps in modeling particle coagulation. |
Monday, November 25, 2024 5:50PM - 6:03PM |
T31.00006: Shock wave interaction with an array of conical deflectors Rijin Rajan, Pratik Rajput, Amar Yadav, Pawan K Karn, Kamal Poddar, Debopam Das Blast protection deflectors are required to reduce the impact of explosions. We present an experimental study where the interaction between shock waves and an array of conical deflectors is qualitatively analyzed to assess the shock-mitigating effect. An array of conical deflectors of tip angle 1100 and hydraulic diameter 90 mm are placed 75 mm away from the exit of the shock tube. The Schlieren flow visualization method was used to study the behavior of flow exiting the open shock tube at Mach 1.49 as it interacts with an array of conical deflectors mounted on a flat plate. The incident shock reflects from the conical deflectors with a speed of 390 m/s. The incident shock wave first reflects off the central cone, followed by successive reflections from the surrounding cones. Additionally, the shock wave reflects from the spaces between the plates, and eventually, all the reflections converge to form a single strong reflected shock. The reflected shock interacts with the compressible vortex ring and the trailing jet. The embedded shock and central Mach disk are visible in front of the jet stream. Additionally, the interaction between the compressible vortex ring and the cones is observed in the visualization. |
Monday, November 25, 2024 6:03PM - 6:16PM |
T31.00007: Experimental and Numerical Investigation of Shock-Wave Generation in Water by Electrical Wire Explosions Sebastián Rojas Mata, Francesc Hernández Garcia, Michael Liverts Electrical wire explosions (EWEs) are performed in water using a 26-kilovolt pulsed power generator (PPG) to generate extreme fluid conditions. Kiloamp currents are discharged through a thin copper wire, causing it to rapidly transition from a solid into an expanding plasma which produces a cylindrical shock wave. Using voltage-current time traces and high-speed imaging, the system's performance is characterized by conducting EWEs with different μm-diameter wires and initial energies. Calculation of the transferred electrical energy and initial mechanical energy of the shock waves indicates gigawatt-level power delivery, shock pressures in the hundreds of MPa, and Mach numbers up to 1.8. The experimental results are compared to numerical simulations which couple a 0-D magnetohydrodynamic model for the wire expansion, a 1-D Euler model for the shock wave propagation, and an RLC circuit model for the PPG. These simulations implement SESAME tables to evaluate the equations of state for copper and water. The comparison between experiments and simulations provides insight into the simulations' ability to capture the multiscale physics of shock generation through EWEs. |
Monday, November 25, 2024 6:16PM - 6:29PM |
T31.00008: Abstract Withdrawn
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Monday, November 25, 2024 6:29PM - 6:42PM |
T31.00009: Impact of height of burst on fireball expansion in C4 explosions Jason Dwonzyk, Matthew Spencer, Michael J Hargather Studying the interface between explosive product gases and ambient air during an explosion |
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