Shock tube

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

Contact surface tailoring condition for shock tubes with different driver and driven section diameters

Abstract: The contact surface tailoring conditions normally used for shock tubes do not apply to shock tubes with different driver and driven section diameters. A theoretical model is presented that predicts the contact surface tailoring condition for a convergent shock tube, designed to have a larger driver cross-section area than the driven section. The tailoring condition previously developed for shock tubes with uniform driver and driven diameters can be recovered from this model. Representative on- and off-model performance is verified experimentally in a high-pressure convergent shock. Tailoring conditions calculated with the model are also given for commonly used driven gases (Ar, N2 and air) and He–N2 driver mixtures as a function of driver/driven area ratio.

Rate and mechanism of thermal decomposition of 4-methyl-l-pentyne in a single-pulse shock tube

Abstract: Dilute mixtures of 4-methyl-l-pentyne have been pyrolyzed in a single-pulse shock tube. The decomposition process involves bond breaking: as well as a molecular reaction: The rate parameters are: The heat of formation of propynyl radical is thus ΔHf300 = 338 kJ mol−1 (80.7 kcal mol−1)˙ This leads to a propynyl resonance energy of 40 kJ mol−1 (9.6 kcal mol−1).

An experimental and modeling study of the shock tube ignition of a mixture of n-heptane and n-propylbenzene as a surrogate for a large alkyl benzene

Abstract: Alkyl aromatics are an important chemical class in gasoline, jet and diesel fuels. In the present work, an n -propylbenzene and n -heptane mixture is studied as a possible surrogate for large alkyl benzenes contained in diesel fuels. To evaluate it as a surrogate, ignition delay times have been measured in a heated high pressure shock tube (HPST) for a mixture of 57% n -propylbenzene/43% n -heptane in air (≈21% O 2 , ≈79% N 2 ) at equivalence ratios of 0.29, 0.49, 0.98 and 1.95 and compressed pressures of 1, 10 and 30 atm over a temperature range of 1000–1600 K. The effects of reflected-shock pressure and equivalence ratio on ignition delay time were determined and common trends highlighted. A combined n -propylbenzene and n -heptane reaction mechanism was assembled and simulations of the shock tube experiments were carried out. The simulation results showed very good agreement with the experimental data for ignition delay times. Sensitivity and reaction pathway analyses have been performed to reveal the important reactions responsible for fuel oxidation under the shock tube conditions studied. It was found that at 1000 K, the main consumption pathways for n -propylbenzene are abstraction reactions on the alkyl chain, with particular selectivity to the allylic site. In comparison at 1500 K, the unimolecular decomposition of the fuel is the main consumption pathway.

Shock-Tube Experiments on Inhibition of the Hydrogen—Oxygen Reaction

Abstract: The ignition of hydrogen—oxygen—argon mixtures containing small amounts of CH4, C2H4, CF3Br, and 1,2‐C2F4Br2 was studied in a shock tube at 970°—1300°K. All four additives inhibited ignition of the gas mixture, higher temperatures being required to give ignition in a given time than when no inhibitor was present. The additives are consumed during the ignition, CH4 and C2H4 being converted mainly to CO, CF3Br to CF3H, and C2F4Br2 to C2F4 in the relatively rich mixture studied. The data have been correlated in terms of elementary chemical reactions. Pyrolysis of CF3Br and C2F4Br2 was studied to aid in the interpretation of the inhibition process.