Wyniki wyszukiwania - BazTech

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Symulacja śledzenia składu gazu w gazociągu przesyłowym

Bleschke Tomasz, Chaczykowski Maciej

Gaz, Woda i Technika Sanitarna

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2023

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Nr 9

2--7

PL

W pracy przeanalizowano śledzenie udziału molowego wodoru w dwuskładnikowej mieszaninie z metanem poprzez rozwiązywanie równania adwekcyjnego transportu masy. Równanie zostało rozwiązanie metodą objętości skończonych za pomocą dwóch schematów różnicowych wyższych rzędów WENO-Z oraz TVD. Schematy wykorzystano do rozwiązania nieustalonego przepływu gazu w pojedynczym rurociągu. W obliczeniach stosowano zarówno model gazu doskonałego, jak i model gazu rzeczywistego. Oba schematy pozwoliły na otrzymanie poprawnych wyników.

EN

This paper analyzes the tracking of hydrogen fraction in a binary mixture with methane by solving the advection equation. The equation was solved using finite volume method and two high order numerical schemes WENO-Z and TVD. The schemes were used to solve the transient flow in a single pipeline. Ideal-gas and real-gas models were used in the calculations. Both schemes allowed obtaining correct results.

2

Numerical Simulation of the Deflagration to Detonation Transition in Granular High-Energy Solid Propellants

Zhen Fei, Wang Liqiong, Wang Zhuoqun

Central European Journal of Energetic Materials

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2019

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Vol. 16, no. 4

504--519

EN

This paper describes a one-dimensional code developed for analyzing the two-phase deflagration to detonation transition (DDT) phenomenon in granular high-energy solid propellants. The deflagration to detonation transition model was established based on a one-dimensional two-phase reactive flow model involving basic flow conservation equations and constitutive relations. The whole system was solved using a high resolution 5th-order WENO (Weighted Essentially Non-Oscillatory) scheme for spatial discretization, coupled with a 3rd-order TVD Runge-Kutta method for time discretization, to improve the accuracy and prevent excessive dispersion. An inert two-phase shock tube problem was carried out to access the developed code. The DDT process of high-energy solid propellants was simulated and the parameters of detonation pressure, run distance to detonation and time to detonation were calculated. The results show that for a solid propellant bed with solid volume fraction 0.65, the run distance to detonation was about 120 mm, the detonation induced time was 28 μs, and the detonation pressure was 18 GPa. In addition, the effects of solid volume fraction (φs) and pressure exponent (n) on the deflagration to detonation transition were also investigated. The numerical results for the DDT phenomenon are in good agreement with experimental results available in the literature.

3

Impact of subgrid modelling and numerical method on autoignition simulation of two-phase flow

Stempka J.

Archives of Thermodynamics

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2018

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Vol. 39, no 2

55--72

EN

The present work focuses on analyses of the autoignition delay time predicted by the large eddy simulation (LES) method by applying different subgrid scales (SGS) models and two different discretization schemes. The analysed flow configuration is a two-phase chemically reacting turbulent flow with monodispersed evaporating fuel droplets. The impact of numerical procedure is investigated in a 3D flow domain with a temporally evolving mixing layer that constituted between the streams of fuel and oxidizer that moved in opposite directions. The upper stream of cold gas carries a dispersed fuel spray (ethanol at 300 K). The lower stream is a hot air at 1000 K. Three commonly used in LES, SGS models are investigated, namely: classical Smagorinsky model, model proposed by Vreman and the σ-model proposed by Nicoud. Additionally, the impact of two discretization schemes, i.e., total variation diminishing (TVD) and weighted essentially nonoscillatory (WENO) is analysed. The analysis shows that SGS model and discretization scheme can play a crucial role in the predictions of the autoignition time. It is observed that for TVD scheme the impact of SGS model is rather small. On the contrary, when the WENO scheme is applied the results are much more dependent on the SGS model.

4

Third-order WENO method on 3D unstructured tetrahedral mesches

Rokicki J., Wieteska R.

Systems : journal of transdisciplinary systems science

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2006

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Vol. 11, nr 1

74-85

EN

The paper discusses finite volume WENO reconstruction applied to simulation of compressible 3D Euler flows using unstructured tetrahedral meshes. The main point of interest is the case when the mesh becomes highly irregular or stretched. Special transformation is used in such cases to recover the third-order accuracy of reconstruction. This transformation has to be locally applied to each stencil on which the reconstruction is sought. This procedure is verified first on a sequence of 3D meshes in a unit cube. The performance of the full algorithm (including the extended nonlinear weighing) is verified for the 3D subsonic and transonic flows in a channel with smooth sinusoidal bump.