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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, a CW laser absorption diagnostic for in-situ measurement of methane mole fraction at high temperatures is developed, where the selected transitions for the diagnostic are a cluster of lines near 3148.8 cm−1 from the R-branch of the ν3 band of the CH4 absorption spectrum.
Abstract: A sensitive CW laser absorption diagnostic for in-situ measurement of methane mole fraction at high temperatures is developed. The selected transitions for the diagnostic are a cluster of lines near 3148.8 cm−1 from the R-branch of the ν3 band of the CH4 absorption spectrum. The selected transitions have 2–3 times more sensitivity to CH4 concentration than the P-branch in the 3.3 μm region, lower interference from major interfering intermediate species in most hydrocarbon reactions, and applicability over a wide range of pressures and temperatures. Absorption cross-sections for a broad collection of hydrocarbons were simulated to evaluate interference absorption, and were generally found to be negligible near 3148.8 cm−1. However, minor interference from hot bands of C2H2 and C2H4 was observed and was characterized experimentally, revealing a weak dependence on wavelength. To eliminate such interferences, a two-color on-line and off-line measurement scheme is proposed to determine CH4 concentration. The colors selected, i.e., for on-line (3148.81 cm−1) and off-line (3148.66 cm−1), are characterized between 0.2–4 atm and 500 K–2100 K by absorption coefficient measurements in a shock tube. Minimum detectable levels of CH4 in shock tube experiments are reported for this range of temperatures and pressures. An example measurement is shown for sensitive detection of CH4 in a shock tube chemical kinetics experiment.
48 citations
TL;DR: The electron density profile behind normal shock waves in air at initial pressures 0.02 ≤ p1 ≤ 0.2 mm Hg and in the shock-Mach-number range 14 ≤ Ms ≤ 20 has been measured, using microwave reflection and magnetic induction probes in a 24-in. diameter shock tube as mentioned in this paper.
Abstract: The electron density profile behind normal shock waves in air at initial pressures 0.02 ≤ p1 ≤ 0.2 mm Hg and in the shock‐Mach‐number range 14 ≤ Ms ≤ 20 has been measured, using microwave‐reflection and magnetic‐induction probes in a 24‐in.‐diameter shock tube. It was found that the electron density generally rises rapidly behind the shock front without much incubation to a transient peak value which is considerably higher (i.e., by a factor of between 2 and 3) than that corresponding to the final equilibrium value. At a fixed shock Mach number, the maximum electron density gradient behind the shock appears to vary with the square of the initial air density, indicating that all the important rate‐governing steps are due to binary collisions. Thus, at Ms = 20, the distance behind the shock required to reach 90% of the transient peak electron density was found to be about 10 times the viscosity mean free path of the undisturbed gas ahead of the shock. At Ms = 14, the corresponding distance was found to be a...
48 citations
TL;DR: In this article, the authors investigated the start-up phase of the shock tube experiment with extended thermodynamics and showed that in the limit of very small times the solution of ET for the startup phase converges to the free-flight-equation.
Abstract: In this paper we investigate the shock tube experiment with extended thermodynamics. Extended thermodynamics (ET) provides dissipative field equations for monatomic gases which are symmetrically hyperbolic. The theory relies on the extension of the set of variables in order to describe extreme nonequilibrium processes. As an example for such a process we focus on the start-up phase of the shock tube experiment. We show numerically that ET succeeds to describe this short time behavior. For small times more and more variables are needed for a physically valid description. In the limit of very small times the solution of ET for the start-up phase converges to the solution of the free-flight-equation. Additionally it turns out that the system of Navier–Stokes and Fourier fails to describe the start-up phase of a shock tube even qualitatively.
48 citations
TL;DR: In this paper, a numerical and experimental investigation of low-temperature auto-ignitions behind reflected shock waves in which a shock tube was employed as the experimental system was performed, and the Schlieren method was used to visualize the ignition phenomena.
48 citations
TL;DR: Ben-Dor, Takayama, and Kawauchi as mentioned in this paper used a 5 × 7 cm ordinary pressure-driven shock tube to investigate the transition from regular reflection to Mach reflection.
Abstract: Shock reflections over a convex and a concave wedge were investigated by using a 5 × 7 cm ordinary pressure-driven shock tube. Dry air was used for both the driving and driven gases. The large difference between the transition from regular (RR) to Mach reflection (MR) and that from MR to RR was observed, confirming the results obtained by Ben-Dor, Takayama & Kawauchi (1980). These results contradict all of the previous theoretical transition criteria. A new theory on the transition between RR and MR was developed by applying Whitham's ‘ray shock’ theory. This new theory agrees quite well with the experimental results.
48 citations