Jason Damazo

Shock propagation through a bubbly liquid in a deformable tube

Shock propagation through a bubbly liquid contained in a deformable tube is considered. Quasi-one-dimensional mixture-averaged flow equations that include fluid–structure interaction are formulated. The steady shock relations are derived and the nonlinear effect due to the gas-phase compressibility is examined. Experiments are conducted in which a free-falling steel projectile impacts the top of an air/water mixture in a polycarbonate tube, and stress waves in the tube material and pressure on the tube wall are measured. The experimental data indicate that the linear theory is incapable of properly predicting the propagation speeds of finite-amplitude waves in a mixture-filled tube; the shock theory is found to more accurately estimate the measured wave speeds.

Plastic Response of Thin-Walled Tubes to Detonation

Elastic and plastic deformation of tubes to internal detonations and the shock waves produced by their reflection were investigated. The study included experimental measurements as well as computational modeling. Tests with stoichiometric ethylene-oxygen mixtures were performed at various initial pressures and strain was measured on thin-walled mild-steel tubes. The range of initial pressures covered the span from entirely elastic to fully plastic deformation modes. A model for the pressure load on the tube wall was developed and tested against experimental measurements. This model was applied as a boundary condition in both a single degree of freedom model of the tube cross section and a finite element model of the entire tube. Comparison of computational and experimental results showed reasonable agreement if both strain-rate and strain-hardening effects were accounted for. A unique mode of periodic radial deformation was discovered and explained through modeling as the result of flexural wave interference effects.

Shock Wave–Boundary Layer Interaction from Reflecting Detonations

The present work is concerned with the differences in how shock and detonation waves inside pipes or ducts reflect from closed ends. One of the motivations for the present study is that the large pressure rise associated with a detonation poses a hazard to pipes that contain flammable mixtures [1]. A detonation impinging normally on a planar wall creates a reflected shockwave to bring the flowat the wall to rest [2] and produces pressures 2.4 times that of an incident Chapman-Jouguet (CJ) detonation [3]. In examining the material deformation produced by reflected detonation loading [4] an inconsistency was discovered between the measured pressure jump across the reflected shock wave and the measured speed of the shock, with the measured pressure being as much as 25% below that predicted by the shock jump relations for the given shock speed. This was theorized to be due to bifurcation of the reflected shock wave associated with shock-wave boundary layer interaction.

Boundary Layer Profile Behind Gaseous Detonation as it Affects Reflected Shock Wave Bifurcation

The present study explores the flow field created by reflecting detonations using heat transfer and pressure measurements near the location of detonation reflection. Schlieren imaging techniques are used to examine the possibility of shock wave-boundary layer interaction. These measurements are compared to laminar boundary layer theory and a one- dimensional model of detonation reflection. Experiments were carried out in a 7.6 m long detonation tube with a rectangular test section using mixtures of stoichiometric hydrogen- oxygen with argon dilution of 0, 50, 67, and 83% at an initial pressure of 10, 25, and 40 kPa. Optical observations show that minimal interaction of the reflected shock wave results when propagating into the boundary layer created by the incident wave. The heat transfer rate is qualitatively consistent with the time dependent laminar boundary layer predictions, however the magnitude is consistently larger and substantial (factor of three) peak-to-peak fluctuations are observed. The pressure measurements show good agreement between predicted ideal incident and reflected wave speeds. The pressure amplitudes are under-predicted for no argon dilution cases particularly at 40 kPa, but in reasonable agreement for lower pressures and higher dilutions.