Effect of corona discharge on detonation initiation with a weak energy source

The effect of corona discharge on the initiation of detonation in a shock tube was studied. The dependence of the wave propagation velocity of the combustion reaction of a propane-butane mixture at different stoichiometric ratios on the amount of admixed nitrogen was measured. It was concluded that the corona initiation of detonation is more effective than the conventional spark initiation.     

Branched-chain nature of hydrogen combustion in the detonation mode

Minor admixtures of the simplest hydrocarbons can prevent detonation and break down a steady-state detonation wave in hydrogen-air mixtures at atmospheric and higher pressures. Therefore, the determining role in the appearance and propagation of the detonation wave is played by the branched mechanism and, accordingly, by the competing chain branching and termination reactions. Without taking into account these reactions, combustion theory cannot explain the basic regularities of the process, including the concentration limits of detonation.     

Numerical investigation of flame propagation in pulse detonation engine with variation of obstacle clearance

Journal of Thermal Analysis and Calorimetry - The objective of present research work is to investigate the combustion flame acceleration and performance of pulse detonation engine (PDE). The PDE...     

The role of molecular-kinetic and thermal factors in inhibition of steady detonation

It was experimentally shown that the reaction of the combustion of hydrogen–air mixtures in a detonation wave virtually completely (with an accuracy of 1%) occurs by a branched-chain mechanism; it is this mechanism that determines the characteristics of the detonation wave.     

VLW equation of state of detonation products

Based on the virial theory, we proposed VLW equation of state of detonation products (VLW EOS). Its basic theory and applications were described. The distinct features of the VLW EOS were First, the detonation performance of the new high energy density materials could be predicted more reliably. Second, it had extensive application. The detonation parameters of both the condensed high energy density materials and the gaseous fuel air explosives could be calculated. Moreover, combustion performance of propellants could also be precisely calculated. The calculation results were satisfactory. Supported by the National Natural Science Foundation of China (Grant No. 1860382), and the Science Foundation of China Academy of Engineering Physics (Grant Nos. 920513, 9401009 & 960577)     

Breakup of steady-state detonation in hydrogen-air mixtures under the action of propane admixtures

Minor amounts of propane effectively inhibit the detonation of hydrogen-air mixtures at atmospheric pressure. Controlled variation of the amount of the admixture provides means to break up the steady-state detonation wave at a preset distance from the place of its origination and to regulate its velocity in a certain range. This is possible due to the branched chain character of the combustion reaction in the detonation mode. Propane is not inferior to propylene in the effectiveness of action on detonation and, owing to its low cost and higher availability, is preferable as a means of preventing the explosion and detonation of hydrogen-air mixtures.     

Scientific foundations and effective chemical methods of combustion,explosion, and gas detonation control

The competition between the branching and termination of reaction chains is shown to determine all general laws of gas combustion and explosion not only at pressures much lower that atmospheric, but also at atmospheric and increased pressures upon self-heating. It is established that the role of any elementary reaction in combustion is determined primarily by its effect on the relation between the rates of chain branching and termination. Scientific foundations and effective chemical methods of combustion, explosion, and combustible gas detonation control are developed.     

Problems of combustion,explosion, and gas detonation in the theory of nonisothermal chain processes

Results of the studies show that the occurrence of chain avalanches is a necessary condition of gasphase processes of combustion not only at pressures tens of times lower than atmospheric pressure, as was thought earlier, but at almost any higher pressures in any temperature regime. It is concluded that considering the specifics of nonisothermal chain processes over a broad range of pressures allows us to explain and adequately describe observed features of combustion, explosion, and detonation (including some that were unexplained earlier). New laws important in theory and practice are predicted and revealed.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

Rocket Engine with Continuous Film Detonation of Liquid Fuel

It was experimentally proven for the first time that it is possible to perform continuous detonation combustion of a film of a liquid fuel in the annular combustor of a demonstrator of a liquid-fuel detonation rocket engine. Firing tests revealed a near-limit mode of longitudinally pulsating film detonation and modes of continuous spinning film detonation with one and two detonation waves circulating within the annular gap of the combustor.     

Hydrojet engine with pulse detonation combustion of liquid-fuel

An experimental prototype of an engine of a new type for water transport—pulse detonation hydroramjet—was designed, built, and tested for the first time. Firing test of the prototype with a 2-L combustor was performed on a specially designed test stand with a thrust-measuring frame capable of producing an approach water stream in the form of a submerged jet with a velocity up to 10 m/s. The specific impulse was experimentally measured, ranging from 370 s at high operation frequency (20 Hz) to 1200 s at low operation frequency (1 Hz); i.e., the measured specific impulse of the pulse detonation hydroramjet exceeded that of the best modern liquid rocket engines.     

Critical detonation diameters of highly dispersed energetic substances

The relationship between the critical detonation diameters of energetic substances and their specific surface area was revealed from the results of studying the detonation ability of a series of energetic substances [pentaerythritol tetranitrate (TEN), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitramine (HMX), 2,4,6-trinitrophenylmethylnitramine (tetryl), benzotrifuroxan (BTF), hexanitrohexaazaisowurtzitane (CL-20), dinitrodifurazanylfuroxan (DNTF), dinitrodifurazanylfurazan (NTF), 1,1-diamino-2,2-dinitroethene (FOX-7)]. A mathematical expression for this relationship was suggested. The critical detonation diameters of highly dispersed (micrometer particles) energetic substances were determined by experiments and calculations. These diameters are in the range 0.06–0.8 mm, which makes these substances suitable for use in aerospace engineering, priming systems, detonation manifolds, and explosion logic devices.     

Purification of detonation nanodiamond material using high-intensity processes

New procedures were developed for chemical treatment of detonation nanodiamonds and diamond-containing detonation blend to remove water-insoluble metal-containing impurities. The detonation nanodiamond material is treated with complexing agent solutions under cavitation conditions and at high temperature and pressure. Sodium 2,3-dimercaptopropanesulfonate (Unithiol), disodium dihydrogen ethylenediaminetetraacetate, thiourea, potassium thiocyanate, dicyandiamide, and hexamethylenetetramine are used as complexing agents. The complexing agent concentration in solution is 0.5–20 wt % at the nanodiamond material to complexing agent weight ratio higher than 0.2. The use of aqueous solutions of the complexing agents at high temperatures and pressures appeared to be the most efficient.     

Surface modification of detonation nanodiamonds by the perfluorobutyl radical

The method was developed for surface defunctionalization of detonation nanodiamonds by substitution of a perfluorinated organic radical for hydroxyl and carboxyl groups. Size-mass distributions of modified particles of detonation nanodiamonds in water and toluene were studied     

Molecular design of prismane-based potential energetic materials with high detonation performance and low impact sensitivity

To develop new energetic materials, the eleven nitroester substitution derivatives of prismane were investigated at the B3LYP/6-311G** level of density functional theory (DFT). The gas phase heats of formation were calculated by isodesmic reactions and the solid-state heats of formation were obtained by the Politzer approach using the heats of sublimation for the designed compounds. The detonation velocities and pressures of all molecules were calculated by Kamlet–Jacobs equations based on molecular density and heat of detonation. The results show that the nitroester group in prismane is helpful for enhancing molecular detonation properties and power index. Among all molecules, 1,2,3,4-tetrnitroesterprismane has excellent detonation properties (detonation pressure = 40.05 GPa, detonation velocity = 9.28 km/s) and large power index value. The molecular stabilities were evaluated by calculating bond dissociation energies and characteristic heights (H₅₀). The results indicate that the bond dissociation energies of all molecules are above 80 kJ/mol, and all molecules have a larger H₅₀ value than hexanitrohexaazaisowurtzitane (CL-20, 12 cm). The obtained structure–property relationships may provide basic information for the molecular design of novel high-energy materials.     

Treatment of detonation carbon in supercritical water

Experimental data on the treatment of detonation carbon in supercritical water are given.     

Nafion- and aquivion-based nanocomposites containing detonation nanodiamonds

Russian Journal of General Chemistry - Nafion- and Aquivion-based composite solid polyelectrolytes containing deagglomerated detonation nanodiamonds were studied by the impedance spectroscopy...     

Combustion science and problems of contemporary power engineering

Nowadays fine control of physical and chemical processes at combustion and detonation of hydrocarbon fuels, aimed at obtaining certain target characteristics for power engineering applications is getting more realistic. Since control implies deep understanding of interrelations between various phenomena, the role of basic science is crucial for attacking the problem. Discussed in the paper are the latest scientific accomplishments in the field of combustion and detonation control, in particular, the possibility of controlled flameless combustion of gases, controlled combustion in porous matrices, and controlled detonations, as well as the problems of practical implementation of controlled combustion and explosion.     

Computational investigation of the heat of formation, detonation properties of furazan-based energetic materials

The heats of formation (HOFs) for a series of furazan-based energetic materials were calculated by density functional theory. The isodesmic reaction method was employed to estimate the HOFs. The result shows that the introductions of azo and azoxy groups can increase the HOF, but the introduction of azo group can increase the more HOF, when compared with azoxy group. The detonation velocities and detonation pressures of the furazan-based energetic materials are further evaluated at B3LYP/6-31G* level. Dioxoazotetrafurazan and azoxytetrafurazan may be regarded as the potential candidates of high-energy density materials because of good detonation performance. In addition, there are good linear correlations between OB and detonation velocities, and OB and detonation pressures. The energy gaps between the HOMO and LUMO of the studied compounds are also investigated. These results provide basic information for the molecular design of novel high-energy density materials.     

Biological activity of detonation nanodiamond and prospects in its medical and biological applications

The present review summarizes and analyzes recent advances in the field of medical and biological applications of detonation nanodiamond and, on this basis, considers most promising ways of creation of anticancer and antimicrobial drugs, diagnostic agents, and nanocompositions for orthopedic surgery. In addition, progress in the surface chemistry of detonation nanodiamond is discussed and problems related to purposeful surface modification with a view to obtain detonation nanodiamond with desired properties ensuring their successful application in biology and medicine are considered.