Topic
Shock tube
About: Shock tube is a research topic. Over the lifetime, 6963 publications have been published within this topic receiving 99372 citations.
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TL;DR: In this paper, an inviscid model for deflagration-to-detonation transition in granular energetic materials is extended by adding explicit intraphase momenta and energy diffusion so as to enable the use of a straightforward numerical scheme.
Abstract: An inviscid model for deflagration-to-detonation transition in granular energetic materials is extended by addition of explicit intraphase momenta and energy diffusion so as to (1) enable the use of a straightforward numerical scheme, (2) avoid prediction of structures with smaller length scales than the component grains, and (3) have a model prepared to describe long time scale transients that are present in some slow processes which can lead to detonation. The model is shown to be parabolic, frame invariant, and dissipative. Consideration of the characteristics for cases with and without intraphase diffusion indicate what boundary conditions are necessary for a well posed problem. A simple numerical method, based on a method of lines applied to the nonconservative form of the equations, is shown to predict convergence at the proper rate to unique solutions which agree well with known solutions for an unsteady inviscid shock tube and a steady piston-driven viscous shock. A series of simulations of inert piston-driven subsonic compaction waves in which the additional mechanisms of interphase compaction, drag, and heat transfer are systematically introduced at an order of magnitude suggested by experiments reveals that interphase drag and heat transfer equilibrate velocities and temperatures, and that compaction equilibrates solid and configurational stresses. At higher piston velocities, supersonic shock and compaction waves are induced; comparison of predictions with and without viscosity demonstrate some of the computational advantages of explicit inclusion of diffusion. The local dissipation rates for each mechanism are quantified, and it is seen that dissipation due to compaction dominates that due to intraphase and interphase transport of linear momenta and energy, suggesting that compaction is the key mechanism in inducing the transition to detonation in piston-driven experiments.
42 citations
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TL;DR: In this paper, the authors used time-resolved stereo particle-image velocimetry (TR-SPIV) and unsteady pressure measurements of transonic flow in a supercritical DRA-2303 airfoil to analyze the origin and nature of the dynamic shock wave-boundary layer interaction.
Abstract: Time-resolved stereo particle-image velocimetry (TR-SPIV) and unsteady pressure measurements are used to analyze the unsteady flow over a supercritical DRA-2303 airfoil in transonic flow. The dynamic shock wave–boundary layer interaction is one of the most essential features of this unsteady flow causing a distinct oscillation of the flow field. Results from wind-tunnel experiments with a variation of the freestream Mach number at Reynolds numbers ranging from 2.55 to 2.79 × 106 are analyzed regarding the origin and nature of the unsteady shock–boundary layer interaction. Therefore, the TR-SPIV results are analyzed for three buffet flows. One flow exhibits a sinusoidal streamwise oscillation of the shock wave only due to an acoustic feedback loop formed by the shock wave and the trailing-edge noise. The other two buffet flows have been intentionally influenced by an artificial acoustic source installed downstream of the test section to investigate the behavior of the interaction to upstream-propagating disturbances generated by a defined source of noise. The results show that such upstream-propagating disturbances could be identified to be responsible for the upstream displacement of the shock wave and that the feedback loop is formed by a pulsating separation of the boundary layer dependent on the shock position and the sound pressure level at the shock position. Thereby, the pulsation of the separation could be determined to be a reaction to the shock motion and not vice versa.
42 citations
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25 Apr 2009
TL;DR: In this paper, the authors discuss the evolution of reactive gaseous systems in equilibrium and non-equilibrium Collisional Regimes, and propose a generalized Chapman-Enskog Method macroscopic approach.
Abstract: Fundamental Statistical Aspects 1. Statistical Description and Evolution of Reactive Gaseous Systems 2. Equilibrium and Non-equilibrium Collisional Regimes 3. Transport and Relaxation in Quasi-Equilibrium Regimes: Pure Gases 4. Transport and Relaxation in Quasi- Equilibrium Regimes: Gas Mixtures 5. Transport and Relaxation in Non- Equilibrium Regime 6. Generalized Chapman- Enskog Method Macroscopic Aspects and Applications 7. General Aspects of Gaseous Flows 8. Elements of Gas Dynamics 9. Reactive Flows 10. Reactive Flows in Dissipative Regime 11. Facilities and Experimental Methods 12. Relaxation and Kinetics in Shock Tube and Shock Tunnel
42 citations
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01 Jan 1965TL;DR: In this article, the authors investigated the effect of slow vibrational relaxation of O 2 on the hydrogen-oxygen ignition kinetics, and showed that in normal studies of normal studies, no effect was observed.
Abstract: The hydrogen-oxygen reaction was investigated using OH absorption and emission measurements of induction times over the temperature range of 1400°–2500°K. The dependence of induction time on composition was studied to measure the relative influence of hydrogen and oxygen concentrations in determining the induction times. Comparison of experimental measurements with computed values obtained from an analytic solution to the rate equations, which is presented in detail, showed that the results could be understood in terms of rate-coefficient parameters which are in agreement with previous studies. The effect of slow vibrational relaxation of O 2 was investigated under conditions where the vibrational relaxation times were comparable to the induction times. The results indicated that in normal studies of hydrogen-oxygen ignition kinetics no effect of slow vibrational relaxation will be observed.
42 citations
01 Dec 1959
TL;DR: The performance of simple Constant-Area Shock tubes was investigated in this paper, where observed flows in a constant-area shock tube were modeled and observed flows were observed in a simple constant area shock tube.
Abstract: : Contents: Performance of Simple Constant-Area Shock tubes; Observed flows in a constant-area shock tube; Production of strong shock waves; Application of the shock tube; Shock-tube materials; Design and Construction; and shock-tube.
42 citations