Wyniki wyszukiwania - Biblioteka Nauki

1

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

100%

Barnat W. , Panowicz R. , Niezgoda T.

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tom 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.

2

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

75%

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

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2016

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tom 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

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

63%

Likhachev D. , Kulagin V.

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tom 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.

4

Wpływ ukształtowania dna pojazdu na impuls ciśnienia wybuchu dużego ładunku

63%

Barnat W.

Modelowanie Inżynierskie

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2012

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tom 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.