The results compare well to 1-D shock calculations.The overall reaction rate for JP10 + OH → products was measured directly via laser absorption of OH in shock tube experiments from 931 to 1308 K and 0.94 to 1.44 atm. Additionally, the current work extends the temperature range of experimental data in the literature for the title reaction under combustion-relevant conditions, presenting the first measurements from 900 to 1000 K. Over the entire temperature range studied, the overall rate constant can be expressed in Arrhenius form as 3.24 × 10(-10) exp(-2505/T [K]) cm(3) molecule(-1) s(-1). In the second method, the laser was tuned at a rate of 3 kH(z) over the R(1)(7) and R(1)(11) line pair, and absorption was simultaneously monitored at 90 and 60 degrees with respect to the flow.
OH radicals were produced by rapid thermal decomposition of the OH precursor tert-butyl hydroperoxide (TBHP) and were monitored by the narrow line width ring dye laser absorption of the well-characterized R(1)(5) line in the OH A-X (0, 0) band near 306.69 nm.
The data were acquired from 900 to 1200 K near 1.1 atm and are best fit by the Arrhenius expression 1.24 × 10(-10) exp(-2501/T [K]) cm(3) molecule(-1) s(-1). The conventional scanned-wavelength strategy, employed in previous diode-laser sensors, is shown to be ill-suited for high-pressure applications.
Transition state theory calculations using recent ab initio results give excellent agreement with our measurements and other data outside our temperature range.
The measured rate constant for the acetone + OH reaction from the current study is consistent with three previous experimental studies from Bott and Cohen (1991), Vasudevan et al. The subsequent visible fluorescence (B(1)Sigma(+) ?
Additionally, shock-treated samples are extracted for ex situ analysis including viability plating, flow cytometry and SEM imaging.
Successful measurements were made at full combustion conditions for a variety of fuel/air equivalence ratios and at eight vertical positions in the duct to investigate spatial uniformity.
At higher pressures, narrowing parameters could not be reliably determined due to the relatively large Ar- and N2-pressure broadening. Good detection sensitivity for water was achieved using tunable diode laser absorption of water at 2550.96 nm within its v(3) fundamental band.
The measured Ar-broadening half-widths were in excellent agreement with calculated values, while the measured shifts were 10 and 20% less than calculated values for the P(3) and P(6) transitions, respectively.
Experiments with the isotopically labeled tert-butan(18)ol also lead to an experimental determination of the branching ratio for the β-scission pathways of the tert-C4H8OH radical by comparing the measured pseudo-first-order decay rate of (16)OH in the presence of excess tert-butan(16)ol with the respective decay rate of (16)OH in the presence of excess tert-butan(18)ol.
A 2006, 110, 6602-6607) in the temperature regime between 1200 and 1700 K. The combination of the two studies suggests only a weak temperature dependence of k(1) above 1200 K. Data from the current study and that of Keyser (Keyser, L.F. J. Phys. Absorbance simulations based on line parameters from HITRAN and HITEMP were found to be similar over the range of temperatures 600-1800 K and were within 25% of the measurements. H atoms generated via reaction 1b rapidly react with O2, which is present in excess, forming OH.
The rate k1 is in the falloff regime at high temperatures, so it was measured at several pressures from 0.6 to 11.5 atm and temperatures from 1349 to 1790 K. OH radicals were formed by shock-heating mixtures of DME and O2 in Ar.
The velocity is determined from the Doppler shift of the fluorescence excitation spectrum, whereas the temperature is inferred from the lineshape.
With the use of both the high-temperature shock tube measurements reported here and the rate coefficient determination of Ellis et al. (2005), and Srinivasan et al. The group has published over 400 archival papers, contributing to advances in shock wave physics and chemistry, laser spectroscopy, advanced optical diagnostics and sensors, chemical …
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Line-shape models that are appropriate for different temperature and pressure regimes are identified.A tunable diode laser diagnostic based on spectrally resolved laser absorption has been developed to detect water vapor. From color stable aliphatic coatings for applications in outdoor environments to fire retardant systems for use in underground mines. Professor Hanson has been the principal advisor for more than … The updated mechanism was first used to reproduce CO, CO2, and H2O concentration time histories during EF pyrolysis in the shock tube reported by Ren et al. Rate constants for the reactions of OH with ethylene and propene were extracted by matching modeled and measured OH concentration time-histories in the reflected shock region.
; Cobos, C.J. The fluorescence is detected simultaneously at 10,000 points in a plane of the flow using a 100 x 100 element photodiode-array camera. Current Students.