Wyniki wyszukiwania - BazTech

1

Analiza parametrów termochemicznych oraz badania zapłonu modyfikowanego paliwa heterogenicznego

Hadzik J., Koślik P., Wilk Z.

Chemik

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2016

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Vol. 70, nr 1

33--40

PL

Artykuł przedstawia wyniki analiz parametrów termodynamicznych dla paliwa MPH modyfikowanego dodatkami tzw. materiałów podsadzkowych – krzemionką i korundem. Wykazano wpływ dodatków na energetyczność paliwa i oszacowano objętość produktów gazowych generowaną z jednostki objętości paliwa. Zaproponowano metodykę badawczą związaną z badaniem zapłonu paliwa MPH, umożliwiającą wyznaczenie charakterystyk energetycznych, określenie maksymalnego ciśnienia gazów postrzałowych oraz całkowitego impulsu ciśnienia.

EN

This paper presents the results of thermodynamic parameters analyzes obtained for MPH propellant modified with additives: silica and corundum. The influence of additives on energetic propellant parameters was shown. The volume of gaseous products generated per unit volume of propellant was estimated. The method of ignition testing MPH propellant was proposed. It allows to determine the energetic characteristics, maximum pressure of the gaseous products and total pressure impulse.

2

Thermobaric Effects of Cast Composite Explosives of Different Charge Masses and Dimensions

Simić D., Andjelić U., Knežević D., Savić K., Draganić V., Sirovatka R., Tomić L.

Central European Journal of Energetic Materials

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2016

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Vol. 13, no. 1

161--182

EN

The aim of this research was to determine the thermobaric effect of cast composite explosives, with different masses and dimensions of the chosen explosive charges. This was done by measuring the shock wave parameters in air (maximum overpressure and pressure impulse) and quantifying the thermal effect (temperature-time dependence), at different distances from the centre of the detonation. The chosen thermobaric explosive composition, TBE-3, was characterized. Its density, detonation velocity and viscosity-time dependence were determined. Experimental samples of different masses and calibres were prepared. The shock wave parameters in air were determined in field tests, by measuring the overpressure by piezo-electric pressure transducers. The detonation and the expansion of the explosion products were filmed by a TV high-speed camera, Phantom V9. An infrared (IR) camera FLIR SC7200 was used for recording the IR scene of the explosions and for tracking the thermal effects by a thermographic technique, i.e. thermal imaging. This work is an initial step towards establishing a method for the quantification of the thermal effects of a thermobaric detonation.

3

Surface wave generation due to glacier calving

Massel S.R., Przyborska A.

Oceanologia

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2013

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No. 55 (1)

101-127

EN

Coastal glaciers reach the ocean in a spectacular process called "calving". Immediately after calving, the impulsive surface waves are generated, sometimes of large height. These waves are particularly dangerous for vessels sailing close to the glacier fronts. The paper presents a theoretical model of surface wave generation due to glacier calving. To explain the wave generation process, four case studies of ice blocks falling into water are discussed: a cylindrical ice block of small thickness impacting on water, an ice column sliding into water without impact, a large ice block falling on to water with a pressure impulse, and an ice column becoming detached from the glacier wall and falling on to the sea surface. These case studies encompass simplified, selected modes of the glacier calving, which can be treated in a theoretical way. Example calculations illustrate the predicted time series of surface elevations for each mode of glacier calving.

4

Wpływ ukształtowania dna pojazdu na impuls ciśnienia wybuchu dużego ładunku

Barnat W.

Modelowanie Inżynierskie

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2012

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T. 14, nr 45

232--240

PL

W pracy przedstawiano wyniki analizy numerycznej dla różnorodnych rodzajów kadłubów wojskowych pojazdów opancerzonych ze szczególnym uwzględnieniem rozchodzenia się impulsu ciśnienia (pochodzącego od dużego ładunku) w podstawowych przypadkach: wybuch w ośrodku Eulera z ograniczeniami wynikłymi z zastosowania gruntu o dużej sztywności i dna pojazdu, wybuch w ośrodku Eulera ograniczonym gruntem i deflektorem wybuchu pod pojazdem z modelem gruntu. Zastosowanie ograniczeń w ośrodku Eulera, w postaci braku wypływu, spowodowało zwiększenie wartości impulsu ciśnienia. Modele pojazdów charakteryzowały się jednakowym prześwitem, odległością pomiędzy najniższym punktem dna pojazdu a płaszczyzną gruntu. Dla celów porównawczych dokonano analizy rozchodzenia się fali ciśnienia dla obszaru Eulera bez ograniczeń. Fala ciśnienia zasymulowana tzw. detonacją punktową rozchodziła się w obszarze o kształcie sześcianu z nadanymi odpowiednimi warunkami brzegowymi.

EN

This paper presents numerical analysis results for two military vehicle's hull shapes. The main emphasis is put on pressure impulse caused by large explosive detonation in two cases: explosion in Euler domain with very stiff ground and vehicle's bottom, explosion in Euler domain with ground and deflector as area boundaries with soil constitutive model. Due to second boundary conditions the pressure impulse is amplified. For both cases the distance between vehicle's bottom and the ground was equal. To compare the results, an analysis of explosion in Euler domain without boundary conditions was performed. Pressure wave propagated in cubic domain with proper boundary and initial conditions.

5

Numerical investigation of the influence of a rigid obstacle on the multiple reflected pressure impulse

Barnat W., Panowicz R., Niezgoda T.

Journal of KONES

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2010

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Vol. 17, No. 4

45-54

EN

The article presents the case of multiple reflection ofa blast wave from a rigid obstacle. The pressure impulse was generated in the Euler domain according to Taylor-Sedov theory. Additionally, there the results of numerical and analytical investigations on the behaviour of the reflected pressure impulse from the flat stiff obstacle were discussed. The analytical considerations are pursuant to the accessible literature. This case is identical with the explosion under a flat bottom of the tank-type vehicle or BWP. All the considered obstacles which are influence by the pressure impulse are similar to the construction of the vehicles used by Polish Army. As it was mentioned above, the numerical investigations were supported by analytical modelsfrom the scientific literature. In the previous papers, the authors conducted the numerical and experimental investigations on the flat blast wave. Those papers concentrated on the selection of the Euler domain parameters and parameters describing an explosive charge for numerical analyses. Additionally, the parameters of the boundary elements of the Euler domain were selected in order to unable the uncontrolled influence of gases. The innovation presented in the paper is the description of the issue of the numerical problem of multiple pressure impulse reflection from a rigid obstacle. The presented papers aim at increasing the safety of the military vehicles crews during the stabilisation missions in Iraq and Afghanistan.

6

Three-dimensional simulation of cavitation flow effects in pipleline system of turbomachines

Likhachev D, Kulagin V

Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka

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2008

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nr 133

213--220

EN

This paper presents a three-dimensional simulation of cavitation bubbles cloud effects on accessories and elements of compressor refrigerating installation, intermediate heat exchanger, as well as pumps and pumping stations. Bubbles appear on sections of these units due to fluid movement. Simulation has demonstrated high dependency of cavitation effects on a cavity shape. Thus, structural solutions subjected to change shapes of cavity can allow minimal cavitation effects on accessories, and elements of hydraulic equipment.

7

Analysis of influence of the shape of protective structures on their energy-absorbing capabilities

Barnat W., Niezgoda T.

Journal of KONES

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2007

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Vol. 14, No. 1

15-26

EN

The paper presents results of numerical investigation of the influence of the shape of a protective element on its energy-absorbing capabilities from the point of view of its resistance to the impact of a shock wave. The works carried out so far confirm that-- as far as the energy-absorbing capabilities are concerned - the shape of the protective element is an important factor. In the paper, results of numerical analysis of basic protective structures in the shape of pyramids, cones and hemispheres were presented. In the numerical models under consideration, dimensions of the base and height of the element were settled. The shape of the base determines the lateral surface of a cone. For the settled dimensions, a cone has the smallest area of the lateral surface and a sphere - the largest. For the models of basic structures, computations were performed with the use of the Dytran programme. As a result of the analysis, deformation of the structures, energy of deformation, velocities and accelerations were obtained. In the paper, a criterion for the assessment of energy absorption capabilities was proposed. It consisted in comparing the results for plates with a protection structure with those for a basic smooth plate in order to assess the level of energy absorbed by the protected plate with respect to the basic one (without protection).The comparison of results for the basic plate and the one with a spherical element shows that the application of the structure would cause the relative displacement of the plate protected a spherical element 50 percent lower than the relative displacement of the plate without protection.

PL

W niniejszym artykule przedstawiono wyniki z przeprowadzonych badań numerycznych nad wpływem kształtu elementu ochronnego na energochłonność pod kątem odporności na działanie fali uderzeniowej. Dotychczasowe prace nad elementami energochłonnymi potwierdzają, iż dość ważnym z punktu widzenia energochłonności jest kształt elementu energochłonnego. W artykule przedstawiono wyniki z analizy numerycznej podstawowych struktur energochłonnych w postaci ostrosłupów stożków i półsfery. W modelach numerycznych ustalono wielkość podstawy oraz wysokość elementu struktury. Kształt podstawy determinuje pole powierzchni elementu. Najmniejsze pole powierzchni bocznej ma stożek. Największe pole powierzchni charakteryzuje sferę. Dla modeli struktur podstawowych wykonano obliczenia programem Dytran. W wyniku analizy numerycznej otrzymano postacie deformacji struktur, energię odkształcenia prędkości oraz przyspieszenia. W pracy przyjęto kryterium oceny energochłonności, polegające na porównaniu wyników płyt ze strukturą ochronną z płytą bazową gładką, w celu oceny zmiany poziomu energii pochłoniętej przez płytę zabezpieczoną w stosunku do płyty bazowej (bez zabezpieczenia). Porównanie wyników dla blachy bazowej i blachy z elementem sferycznym pokazuje, że zastosowane struktury powodowały względne przemieszczenie węzła płyty chronionej elementem sferycznym mniejsze o 50% od względnego przemieszczenia płyty.