High resolution numerical simulation of triple point collision and origin of unburned gas pockets in turbulent detonations

A key issue in pulse detonation engine development is better understanding of the detonation structure and its propagation mechanism. Thus, in the present work the turbulent structure of an irregular detonation is studied through very high resolution numerical simulations of 600 points per half reaction length. The aim is to explore the nature of the transverse waves during the collision and reflection processes of the triple point with the channel walls. Consequently the formation and consumption mechanism of unreacted gas pockets is studied. Results show that the triple point and the transverse wave collide simultaneously with the wall. The strong transverse wave switches from a primary triple point before collision to a new one after reflection. Due to simultaneous interaction of the triple point and the transverse wave with the wall in the second half of the detonation cell, a larger high-pressurised region appears on the wall. During the reflection the reaction zone detaches from the shock front and produces a pocket of unburned gas. Three mechanisms found to be of significance in the re-initiation mechanism of detonation at the end of the detonation cell; i: energy resealed via consumption of unburned pockets by turbulent mixing ii: compression waves arise due to collision of the triple point on the wall which helps the shock to jump abruptly to an overdriven detonation iii: drastic growth of the Richtmyer–Meshkov instability causing a part of the front to accelerate with respect to the neighbouring portions.

Thin-zone TAP reactor as a basis of �state-by-state transient screening

Thin-zone TAP reactor is presented as a basis of the new state-by-state transient screening approach which has been proposed by the authors for non-steady-state kinetic characterization of industrial catalysts. The general thin-zone TAP reactor model is described, and its mathematical status is justified analytically. It is shown that this model provides high enough accuracy to be applicable in the wide conversion interval (up to 90%), which is an important advantage of this approach compared with the traditional differential reactor.

Effective collision strengths for transitions in Fe XIII

Effective collision strengths for transitions among the lowest 97 fine-structure levels belonging to the (1s(2)2s(2)2p(6)) 3s(2)3p(2), 3s3p(3), 3s(2)3p3d, 3p(4), 3s3p(2)3d and 3s(2)3d(2) configurations of Fe XIII have been calculated using the fully relativistic Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2004). Resonances have been resolved in the threshold region, and results are reported over a wide electron temperature range up to log T-e = 6.8 K. Comparisons are made with the earlier available R-matrix results of Gupta & Tayal (1998), and the accuracy of the data is assessed.

Effective collision strengths for transitions in Fe X

Collision strengths for 4005 transitions among the lowest 90 levels of the (1s(2)2s(2)2p(6)) 3s(2)3p(5), 3s3p(6), 3s(2)3p(4)3d, 3s3p(5)3d and 3s(2)3p(3)3d(2) configurations of Fe X have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant, over a wide energy range up to 210 Ryd. Resonances have been resolved in the threshold region, and effective collision strengths have been obtained over a wide temperature range up to 107 K. The present calculations should represent a significant improvement ( in both range and accuracy) over the earlier available results of Bhatia & Doschek and Pelan & Berrington. Based on several comparisons, the accuracy of our data is assessed to be better than 20%, for a majority of transitions.

Radiative rates, collision strengths and effective collision strengths for transitions in Mo XXXIV

Radiative rates for electric dipole (E I), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among the lowest 60 fine-structure levels of the (1s(2)) 2S(2)2p(5), 2s2p(6), and 2S(2)2p(4)3l configurations of F-like Mo XXXIV have been calculated using the fully relativistic GRASP code. Additionally, collision strengths for transitions among these levels have been computed over a wide energy range below 3200Ry, using the Dirac Atomic R-matrix Code. Resonances have been resolved in a fine energy mesh in order to calculate the effective collision strengths. Results for radiative rates and excitation rates are presented for all transitions, and for collision strengths for transitions from the lowest three levels to the higher lying levels. The accuracy of the present data is assessed to be similar to 20%.