Propagation Mechanism of Cylindrical Cellular Detonation

2012 ◽  
Vol 29 (10) ◽  
pp. 108201 ◽  
Author(s):  
Wen-Hu Han ◽  
Cheng Wang ◽  
Jian-Guo Ning
Keyword(s):  
Propagation Mechanism ◽  
Cellular Detonation

scholarly journals Numerical Studies on Propagation Mechanisms of Gaseous Detonations in the Inhomogeneous Medium

2020 ◽  
Vol 10 (13) ◽  
pp. 4585
Author(s):  
Jianguo Ning ◽  
Da Chen ◽  
Jian Li
Keyword(s):  
Inhomogeneous Medium ◽  
Transverse Wave ◽  
Early Stage ◽  
Detonation Front ◽  
Homogeneous Medium ◽  
Wave Structure ◽  
Reaction Model ◽  
Propagation Mechanism ◽  
Gaseous Detonations ◽  
Cellular Detonation

Numerical simulation of propagation mechanisms of gaseous detonations in the inhomogeneous medium is studied by using the reactive Euler equations coupled with a two-step chemical reaction model. The inhomogeneity is generated by placing artificial temperature perturbations with different wavelengths and amplitudes. The motivation is to investigate the effect of artificial perturbations on the evolution or amplification of cellular instability. The results show that, without artificial perturbations, a planar ZND detonation can evolve into a fully-developed cellular detonation after a distance because of the amplification of the cellular instability. With the artificial perturbations evolved in, at the early stage, the artificial perturbations control the transverse wave spacing by suppressing the amplification of the cellular instability. However, after a steady-state, the cellular instability starts to amplify itself again and eventually transits to a fully-developed cellular detonation. It is demonstrated that the presence of the artificial perturbations delays the formation of the cellular detonation, and the increase of instability factor can slow down this delay. It is also found that, if the wavelength of the artificial perturbations is close to the transverse wave spacing of the cellular detonation in the homogeneous medium, synchronization of these two factors occurs, and hence a cellular detonation with extremely regular cell pattern is immediately formed. The temperature discontinuity causes the front to be more turbulent with the presence of weak triple-wave structure locally besides the natural transverse waves. The artificial perturbations can increase the intrinsic instability, and hence changes the propagation mechanism of the detonation front. In contrast, large artificial perturbations could prohibit the propagation but reduce cellular instability. It is concluded that the competition of artificial perturbations with intrinsic detonation instability dominates the evolution of cellular structures of the detonation front.

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

2019 ◽  
Author(s):  
Melanie Short ◽  
Mina Shehata ◽  
Matthew Sanders ◽  
Jennifer Roizen
Keyword(s):  
Hydrogen Atom ◽  
Transfer Reaction ◽  
Hydrogen Atom Transfer ◽  
Chain Propagation ◽  
Propagation Mechanism ◽  
Atom Transfer ◽  
Radical Chain ◽  
Radical Intermediates ◽  
Transfer Processes ◽  
Unusual Position

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp<sup>3</sup>) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp<sup>3</sup>)-H bonds.

Sulfamides Direct Radical-Mediated Chlorination of Aliphatic C–H Bonds

2019 ◽  
Author(s):  
Melanie Short ◽  
Mina Shehata ◽  
Matthew Sanders ◽  
Jennifer Roizen
Keyword(s):  
Hydrogen Atom ◽  
Transfer Reaction ◽  
Hydrogen Atom Transfer ◽  
Chain Propagation ◽  
Propagation Mechanism ◽  
Atom Transfer ◽  
Radical Chain ◽  
Radical Intermediates ◽  
Transfer Processes ◽  
Unusual Position

Sulfamides guide intermolecular chlorine transfer to gamma-C(sp<sup>3</sup>) centers. This unusual position-selectivity arises because accessed sulfamidyl radical intermediates engage in otherwise rare 1,6-hydrogen-atom transfer processes. The disclosed chlorine-transfer reaction relies on a light-initiated radical chain-propagation mechanism to oxidize C(sp<sup>3</sup>)-H bonds.

CHARACTERISTICS OF CELLULAR DETONATION IN CONVERGENT CHANNEL

2019 ◽  
Author(s):  
Q. LIU ◽  
◽  
Y. LIU ◽  
J.H.S. LEE ◽  
◽  
...  
Keyword(s):  
Convergent Channel ◽  
Cellular Detonation

scholarly journals Farm Product Prices, Redistribution, and the Early U.S. Great Depression

2021 ◽  
pp. 1-39
Author(s):  
Joshua K. Hausman ◽  
Paul W. Rhode ◽  
Johannes F. Wieland
Keyword(s):  
Great Depression ◽  
Propagation Mechanism ◽  
Farm Product ◽  
Retail Prices ◽  
Marginal Propensity ◽  
Pass Through

We argue that falling farm product prices, incomes, and spending may explain 10–30 percent of the 1930 U.S. output decline. Crop prices collapsed, reducing farmers’ incomes. And across U.S. states and Ohio counties, auto sales fell most in crop-growing areas. The large spending response may be explained by farmers’ indebtedness. Reasonable assumptions about the marginal propensity to spend of farmers relative to nonfarmers and the pass-through of farm prices to retail prices imply that the collapse of farm product prices in 1930 was a powerful propagation mechanism worsening the Depression.

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