Wyniki wyszukiwania - BazTech

1

Examing the selection of a fuel component for low energy mixtures

Zakusylo Roman, Romanchenko Anzhela

Materiały Wysokoenergetyczne

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2021

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T. 13

82--88

EN

The efficiency of an explosive mixture based on potassium chlorate(VII) (PP) with decomposition catalyst and selected combustible component was determined. The results of researches of the thermodynamic characteristics of explosive mixtures with combustible components (diesel fuel and nitromethane) are presented. Thermodynamic calculations of mixed explosives were performed using the Avakyan method. Energy and explosive characteristics such as heat of explosion, temperature of explosion, volume of gases at explosion, oxygen balance, detonation speed and explosiveness, are determined. According to qualitative and quantitative analysis of gas generation, it is established that toxic gases such as NO2, CO and Cl2 are present in quantities up to 0.13 mol/kg, meaning that the explosives based on PP are safe for the environment and workers in quarries.

PL

Określono wydajność mieszaniny wybuchowej na bazie nadchloranu potasu z katalizatorem rozkładu i wybranym składnikiem palnym. Przedstawiono wyniki badań charakterystyk termodynamicznych mieszanin wybuchowych ze składnikami palnymi (olej napędowy i nitrometan). Obliczenia termodynamiczne mieszanych materiałów wybuchowych przeprowadzono metodą Avakyan. Wyznaczane są charakterystyki energetyczne i wybuchowe, takie jak: ciepło wybuchu, temperatura wybuchu, objętość gazów podczas wybuchu, bilans tlenowy, prędkość detonacji, wysoka wybuchowość. Na podstawie jakościowej i ilościowej analizy powstawania gazów podczas wybuchu ustalono, że gazy toksyczne takie jak NO2, CO i Cl2 występują w ilości do 0,13 mol/kg, w wyniku czego kompozycje wybuchowe oparte na nadchloran potasu są bezpieczne dla środowiska i pracowników kopalni odkrywkowych.

2

Numerical Modelling of Detonation Reaction Zone of Nitromethane by EXPLO5 Code and Wood and Kirkwood Theory

Štimac Barbara, Chan Hay Yee Serene, Kunzel Martin, Suceska Muhamed

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 2

239--261

EN

The detonation reaction zone of nitromethane (NM) has been extensively studied both experimentally and theoretically. The measured particle velocity profile of NM shows the existence of a sharp spike followed by a rapid drop over the first 5-10 ns (fast reaction). The sharp spike is followed by a gradual decrease (slow reactions) which terminate after approximately 50-60 ns when the CJ condition is attained. Based on experimental data, the total reaction zone length is estimated to be around 300 μm. Some experimental observations, such as the reaction zone width and the diameter effect, can be satisfactorily reproduced by numerical modelling, provided an appropriate reaction rate model is known. Here we describe the model for numerical modelling of the steady state detonation of NM. The model is based on the coupling thermochemical code EXPLO5 with the Wood-Kirkwood detonation theory, supplemented with different reaction rate models. The constants in the rate models are calibrated based on experimentally measured particle velocity profiles and the detonation reaction zone width. It was found that the model can describe the experimentally measured total reaction time (width of reaction zone) and the particle velocitytime profile of NM. It was found also that the reaction rate model plays a key role on the shape of the shock wave front. In addition, the model can predict the detonation parameters (D, pCJ, TCJ, VCJ, etc.) and the effect of charge diameter on the detonation parameters.

3

Regularities of the energy of formation field in the explosion of a conical charge

Kravets Viktor, Zakusylo Roman, Sydorenko Yuri, Shukurov Azer, Sałaciński Tomasz, Zakusylo Daryna

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 4

533--546

EN

The process of formation of the energy field by the explosion of a conical charge has been mathematically simulated. The features of the development of the energy field, depending on the point of initiation of the truncated cone explosive charge, were determined. The complex nature of the use of a charge at the bottom of a borehole with an intermediate conically-shaped detonator is discussed. Possible technological directions for using a charge with a complex shape are proposed.

4

Green propulsion research at TNO the Netherlands

Mayer A., Wieling W.

Transactions on Aerospace Research

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2018

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Nr 4 (253)

5--32

EN

This paper describes the recent theoretical and experimental research by the Netherlands Organisation for Applied Scientific Research (TNO) into green replacements for hydrazine, hydrazine derivatives and nitrogen tetroxide, as propellants for inspace propulsion. The goal of the study was to identify propellants that are capable of outperforming the current propellants for space propulsion and are significantly less hazardous for humans and the environment. Two types of propellants were investigated, being monopropellants and bipropellants. The first section of the paper discusses the propellant selection. Nitromethane was found to be the most promising monopropellant. As bipropellant, a combination of hydrogen peroxide (HP) and ethanol was selected, where the ethanol is rendered hypergolic with hydrogen peroxide. The second part of the paper describes the experimental verification of these propellants by means of engine testing. Initiation of the decomposition of nitromethane was found to be problematic, hypergolic ignition of the hydrogen peroxide and ethanol bipropellant however was successfully demonstrated.

PL

W niniejszym artykule opisano wyniki najnowszych teoretycznych i eksperymentalnych badań Holenderskiej Organizacji Stosowanych Badań Naukowych (TNO) na rzecz ekologicznych zamienników hydrazyny, pochodnych hydrazyny i tetratlenku diazotu, jako materiałów do napędu rakietowego. Celem badań była identyfikacja materiałów napędowych, mogących osiągnąć lepsze wyniki niż obecne paliwa rakietowe i będąc jednocześnie mniej niebezpiecznymi dla ludzi i środowiska. Zadano dwa typy materiałów pędnych, tak zwane „monopropellant” i „bipropellant”. W pierwszej części artykułu omówiono wybór materiału pędnego. Nitrometan okazał się najbardziej obiecującym materiałem typu „monopropellant”. Jako „bipropellant” wybrano połączenie nadtlenku wodoru (HP) i etanolu, w którym etanol zmodyfikowano hypergolicznie nadtlenkiem wodoru. W drugiej część artykułu opisano eksperymentalną weryfikację zastosowania materiałów napędowych za pomocą testów silnika. Pomimo początkowych problemów z rozkładem nitrometanu, udowodniono hipergoliczny zapłon nadtlenku wodoru i zademonstrowano „bipropellant” etanolowy.

5

Investigation of the Radical Nitration of Isooctane Fuel via Nitromethane Propellant

Bayar C. C.

Central European Journal of Energetic Materials

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2018

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Vol. 15, no. 2

225--242

EN

The possible radical nitration reactions of isooctane fuel with nitromethane propellant, which is generally used as an additive in fuel formulations, were thermodynamically investigated both at room temperature and at a higher temperature of 691.15 K. The temperature of 691.15 K was chosen because it is the auto-ignition temperature of isooctane and nitromethane and has the potential to mimic better engine conditions. The computational calculations were performed at the theoretical level of DFT UB3LYP/cc-pVDZ. Four different nitration reactions and nitrated products were considered and interpreted in detail. The most and the least favorable nitrations were observed at the primary and secondary carbons of isooctane at 691.15 K, respectively. Four of the designated reactions were endothermic at this temperature. The other outcome of this study was that there was a direct relationship between the thermodynamic tendencies of the considered reactions and the ballistic performances (detonation velocities, detonation pressures, and specific impulses) of their nitrated products. The thermodynamic properties of heats of combustion and deflagration temperatures were calculated via empirical formulations based on the stoichiometry and some other structural parameters of the energetic materials. The results for nitromethane and the nitro-isooctane products were examined.

6

Explosive Characteristics and Shaped Charge Applications of Nitromethane (NM): A Review

Shekhar H.

Central European Journal of Energetic Materials

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2012

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Vol. 9, nr 1

87-97

EN

Nitromethane (NM or CH3NO2 ) has a wide range of applications as a detonating homogeneous liquid explosive. Although, its use as a liquid propellant is more pronounced, the determination and characterization of NM and its mixtures for their various detonation properties has gained in importance. Various researchers have performed initiation studies of NM by shock and jet, and the presence of a superdetonation zone has also been debated. The opacity or otherwise of the reaction and detonation zones has been investigated experimentally. Sensitization or dilution of NM by various additives and the effect on the detonation behavior has also been investigated. In recent times, the use of NM as a field-filled homogeneous filling in shaped charges for the disposal of unexploded ordnance has gained in importance. The experimental observations and related theoretical aspects for the use of NM as a filling for shaped charges are illustrated in this article. Overall, NM can be thought suitable as a viable future alternative for both commercial and military applications.

7

Accounts of the new aspects of nitromethane initiation reactivity

Zeman S., Atalar T., Friedl Z., Ju X-H.

Central European Journal of Energetic Materials

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2009

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Vol. 6, nr 1

119-133

EN

A well-known effect of amines, and also of water, on detonation characteristics of nitromethane (NM) is discussed from the point of view of the published knowledge about the study of initiation reactivity of this nitro paraffin. It is documented that bimolecular and higher interactions during the initiation of NM are impossible. The most widespread concepts of the primary steps of this initiation, i.e. formation of aci-NM anion [CH2=NO2]— by intermolecular hydrogen transfer in the neat NM submitted to shock and formation of this anion by action of an amine, have been scrutinized by the DFT B3LYP/cc-pVTZ+ method and evaluated as thermodynamically disadvantageous. Also the 1,3-intramolecular hydrogen shift in the NM molecule was characterized as a higher-barrier process. Two favorable primary mechanisms of fission in the NM initiation and development of its detonation were investigated by DFT B3LYP/cc-pVTZ+ calculations: homolysis of C–NO2 bond in the neat NM and homolysis of N–OH bond in its aci-form. The second mentioned pathway was found to be thermodynamically the most preferable mechanism of fission. Consequently, a detonation wave of NM with admixture of amine or water has a considerably reduced reaction zone length in comparison with the detonation of neat NM. The B3LYP/6-311++G(d,p) calculations of transition states revealed that an admixture of methylamine and/or water influences the conversion of nitromethane to its aci-form, and this effect is more feasible in the case of methylamine rather than water.

8

Effects of Electric Fields Upon Energetic Molecules: Nitromethane and Dimethylnitramine

Politzer P., Murray J. S., Concha M. C., Lane P.

Central European Journal of Energetic Materials

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2007

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Vol. 4, nr 4

3-21

EN

We have investigated computationally (B3PW91/6-31G**) the effects of electric fields upon certain properties - dipole moments, energies, geometries and electrostatic potentials – of two prototypical energetic molecules, nitromethane and dimethylnitramine. Fields of various strengths and in different directions were considered. The stronger fields significantly polarized the molecular charge distributions, especially when applied parallel to the C-NO2 and the N-NO2 bonds. These directions correspond to the principal polarities of the ground-state molecules, which these parallel fields either reinforce or counteract. With respect to geometries, the changes are primarily conformational, e.g. rotation of the methyl groups or inversion of the pyramidal nitrogen in (H3C)2N-NO2.

9

Isotope effects on selected physicochemical properties of nitromethane and 1-pentanol

Makowska A., Szydłowski J.

Nukleonika

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2006

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Vol. 51,suppl.2

81-85

EN

Densities, kinematic viscosities, speed of sound and refractive indices of nitromethane and 1-pentanol and their deuterated derivatives CD3NO2 and C5H11OD were measured. The data obtained allowed to calculate molar volumes, dynamic viscosities, isentropic compressibilities and isobaric thermal expansion. Deuterium isotope effect on the selected physicochemical properties of both nitromethane and 1-pentanol has been determined. Large isotope effects characterizing density, viscosity and speed of sound are observed for nitromethane and much smaller for 1-pentanol. Isotope effects on molar volume are small both for nitromethane and 1-pentanol, but of the opposite sign. These observations are in agreement with the expectations.