Shock tube

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

Domains and boundaries of non-stationary oblique shock-wave reflexions. 2. Monatomic gas

Abstract: Interferometric data were obtained in the 10 cm × 18 cm hypervelocity shock tube of oblique shock-wave reflexions in argon at initial temperatures and pressures of nearly 300 °K and 15 Torr. The shock Mach-number range covered was 2 [les ] Ms [les ] 8 over a series of wedge angles 2° [les ] θw [les ] 60°. Dual-wavelength laser interferograms were obtained by using a 23 cm diameter field of view Mach-Zehnder interferometer. In addition to our numerous results, the available data for argon and helium obtained over the last two decades were also utilized. It is shown analytically and experimentally that in non-stationary flows six domains exist in the (Ms, θw) plane where regular reflexion (RR), single-Mach reflexion (SMR), complex-Mach reflexion (CMR) and double-Mach reflexion (DMR) can occur. The transition boundaries between these regions were all established analytically. The experimental results from different sources substantiate the present analysis, and areas of disagreement which existed in the literature are now clarified and resolved. It is shown that real-gas effects have a significant influence on the size of the regions and their boundaries. In addition, isopycnics (constant density lines) are given for the four types of reflexion, as well as the density distribution along the wedge surface. This data should provide a solid base for computational fluid dynamicists in comparing numerical techniques with actual experimental results.

Shock tube determination of the rate coefficient for the reaction N2+O→NO+N

Abstract: The rate coefficient for the reaction N 2 + O → k 1 NO + N has been measured in the temperature range 2384–3850 K using a shock tube technique. Test gas mixtures consisting of N2, O2, N2O and Kr were heated by incident shock waves, and the concentration of NO in the post-shock region was monitored using two independent spectroscopic techniques: IR emission at 5.3 μm, and absorption of CO laser radiation at 5.17 μm. The two methods yielded excellent agreement. The importance of interferences from other reactions was minimized by careful tailoring of the test mixture composition, in particular by using N2O rather than O2 as a source of 0 atoms. The rate coefficient k1 was determined by comparing experimental and calculated NO profiles using a computer simulation in which k1 was an adjustable parameter. The results of 20 experiments indicate that k1=1.84×1014 exp (−76,250/RT) cm3/mol×s with an uncertainty of approximately ±35% in the temperature range investigated.

Thermal Decomposition of 2,5-Dimethylfuran. Experimental Results and Computer Modeling

Abstract: The thermal reactions of 2,5-dimethylfuran were studied behind reflected shock waves in a pressurized driver single pulse shock tube over the temperature range 1070−1370 K and overall densities of ∼3 × 10-5 mol/cm3. A large number of products resulting from unimolecular cleavage of the ring and consecutive free radical reactions were obtained under shock heating. A methyl group migration from C(2) to C(3) in the ring with the elimination of CO produces four isomers of C5H8 in unimolecular processes. An additional unimolecular process is the decomposition of 2,5-dimethylfuran to CH3CO and C4H5 which is an important initiator of free radical reactions. Ejection of a hydrogen atom from the methyl group in the molecule is another channel for initiation of free radical reactions in the system. The 2,5-dimethylfuryl radical, which is obtained in the process of H-atom ejection, decomposes in channels similar to those of 2,5-dimethylfuran to produce, among other products, C5H7, which is the precursor of cyclopent...