Shock tube

About: Shock tube is a research topic. Over the lifetime, 6963 publications have been published within this topic receiving 99372 citations.

Experimental Investigations of Cavitation Bubble Collapse by a Water Shock Tube

Abstract: This paper deals experimentally with the mechanism of an impulsive pressure generated by a collapsing bubble. In a water filled shock tube, an expansion wave and a subsequent compression wave are applied to single, twin and triadic bubbles. The growth, collapse and rebound of bubbles situated at various distances from a solid boundary are observed by means of high-speed photography and in-line Fraunhofer holography using a pulsed dye laser. The results indicate that the impulsive pressure is caused by a shock wave radiated at the instant of the rebound of a collapsing bubble, and that the subsequent jet impingement does not produce any detectable effects. The pressure pulse is found to be of the order 104 ∼ 105 atm, and its duration 2 ∼ 3 μsec.

A platform for studying the Rayleigh–Taylor and Richtmyer–Meshkov instabilities in a planar geometry at high energy density at the National Ignition Facility

Abstract: A new experimental platform has been developed at the National Ignition Facility (NIF) for studying the Rayleigh–Taylor (RT) and Richtmyer–Meshkov (RM) instabilities in a planar geometry at high-energy-densities. The platform uses 60 beams of the NIF laser to drive an initially solid shock tube containing a pre-machined interface between dense and light materials. The strong shock turns the initially solid target into a plasma and the material boundary into a fluid interface with the imprinted initial condition. The interface evolves by action of the RT and RM instabilities, and the growth is imaged with backlit x-ray radiography. We present our first data involving sinusoidal interface perturbations driven from the heavy side to the light side. Late-time radiographic images show the initial conditions reaching the deeply nonlinear regime, and an evolution of fine structure consistent with a transition to turbulence. We show preliminary comparisons with post-shot numerical simulations and discuss the impl...

Attenuation of shock waves propagating in polyurethane foams

Abstract: Shock wave attenuation in polyurethane foams is investigated experimentally and numerically. This study is a part of research project regarding shock propagation in polyurethane foams with high-porosities $$\phi_{g}$$ = 0.951 ~ 0.977 and low densities of ρc = 27.6 ~55.8 kg/m3. Sixty Millimeter long cylindrical foams with various cell numbers and foam insertion condition were installed in a horizontal shock tube of 50 mm i.d. and 5.4 mm in length. Results of pressure measurements in air/foam combination are compared with CFD simulation solving the one-dimensional Euler equations. In the case of a foam B fixed on shock tube wall, pressures at the shock tube end wall increases relatively slowly comparing to non-fixed foam, free to move and a foam A fixed on shock tube wall. This implies that elastic inertia hardly contributes to pressure build up. Pressures behind a foam C fixed on shock tube wall decrease indicating that shock wave is degenerated into compression wave. Dimensionless impulse and attenuation factor decrease as the initial cell number increases. The momentum loss varies depending on cell structure and cell number.

Experimental and modeling study of 1-hexene oxidation behind reflected shock waves

Abstract: The auto-ignition delay times τ i of 1-C 6 H 12 /O 2 /Ar mixtures have been measured between 1270 and 1700 K using shock tube technique for 3 equivalence ratios ( Φ = 0.5, 1, and 1.5) at a pressure of about 0.2 MPa. At higher temperatures (>1400 K), the logarithm of τ i varies linearly as a function of the temperature inverse for a given value of equivalence ratio. The apparent activation energy, E a , is approximately equal to 230 kJ mol −1 . At lower temperature ( E a strongly decreases and becomes equal to about 120 kJ mol −1 around 1300 K. A correlation between τ i , reactant concentrations, and temperature behind reflected shock waves was proposed for each temperature range. These correlations give an estimation of τ i with an accuracy better than 12%. A detailed chemical mechanism of the 1-hexene oxidation has been developed with the “EXGAS” program. The agreement between computed and measured values of τ i was correct at high temperatures (>1400 K). The major channels of the chemical species fluxes have been discussed: at low temperatures, 1-hexene is mainly consumed by retro-ene reaction to give propene and, in a smaller ratio, by unimolecular decomposition to give allyl and 1-propyl radicals. At high temperature, unimolecular decomposition becomes more important than retro-ene reaction. The change in E a below 1400 K is not explained by the model. The auto-ignition delay times of 1-hexene have been compared to those of other unsaturated hydrocarbons. For stoichiometric mixtures diluted by 99 mol% of argon at a pressure of 200 kPa, the shortest delays were obtained for 1-octene while the longest delays were obtained for propene. With iso-butene and ethylene, the delay times are closer to 1-hexene in the low temperature side and to propene in the high temperature one.