Modeling steady axis-symmetric thermal plasma flow of air by a parallelized magneto-hydrodynamic flow solver

Chau, Shiu‐Wu; Hsu, Kun-Lin

doi:10.1016/j.compfluid.2011.01.008

Cited by 9 publications

(4 citation statements)

References 14 publications

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“…Thermal plasmas were assumed to be under local thermodynamic equilibrium (LTE) conditions [11]. At a macroscopic level, these kinds of plasma could be considered as conductive fluid mixtures which were governed by the MHD equation [12,13]. MHD equations combine Navier-Stokes, heat transfer and Maxwell equations to describe the motion of the conducting fluid in an electromagnetic field.…”

Section: Basic Theory Of Mhd Modelmentioning

confidence: 99%

Plasma discharge characteristics of segmented diverter strips subject to lightning strike

Han

Wang

Xiong

et al. 2018

Plasma Sci. Technol.

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In order to research segmented diverters for aircraft lightning protection, a transient 2D multiphysics model based on magnetohydrodynamics theory is proposed to predict the location of the arc plasma discharge and lightning channel, and to simulate the electrothermal behavior. Based on numerical calculation and preliminary analysis, factors that affect the breakdown voltage of the segmented diverter are discussed. The results show that the voltage increase rate of the voltage source, the width of the air gap between metal segments and the geometry of these segments influence the breakdown voltage of the strip. High-voltage tests of the segmented diverter are performed to reveal air breakdown of the strip and redirect the lightning current. Experimental and numerical results are compared to verify the correctness of the numerical model. The ionization of the air gap between metal segments and the breakdown voltage of the strip calculated by the model are qualitatively consistent with experimental results. The breakdown voltage of the segmented diverter is far lower than the lightning voltage. When a lightning strike occurs, the segmented diverter can be quickly ionized to form a plasma channel which can guide the lightning current well.

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Section: Basic Theory Of Mhd Modelmentioning

confidence: 99%

Plasma discharge characteristics of segmented diverter strips subject to lightning strike

Han

Wang

Xiong

et al. 2018

Plasma Sci. Technol.

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“…In the method proposed in this study, an in-house code is implemented for the wake flow prediction of wind farms based on the proposed mathematical model where a linear domain decomposition scheme is employed to parallelize the flow computation on a Cartesian gird via the MPI library [22]. A second-order finite volume method based on a deferred correction approach is adopted to discretize the governing equations and a semi-implicit method for pressure-linked equations (SIMPLE) algorithm is employed to decouple velocity and pressure.…”

Section: Solution Processmentioning

confidence: 99%

Power Prediction of Wind Farms via a Simplified Actuator Disk Model

Chiang

Hsu

Chau

2020

JMSE

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This paper aims to demonstrate a simplified nonlinear wake model that fills the technical gap between the low-cost and less-accurate linear formulation and the high-cost and high-accuracy large eddy simulation, to offer a suitable balance between the prediction accuracy and the computational cost, and also to establish a robust approach for long-term wind farm power prediction. A simplified actuator disk model based on the momentum theory is proposed to predict the wake interaction among wind turbines along with their power output. The three-dimensional flow field of a wind farm is described by the steady continuity and momentum equation coupled with a k-ε turbulence model, where the body force representing the aerodynamic impact of the rotor blade on the airflow is uniformly distributed in the Cartesian cells within the actuator disk. The characteristic wind conditions identified from the data of the supervisory control and data acquisition (SCADA) system were employed to build the power matrix of these typical wind conditions for reducing the computation demands to estimate the yearly power production. The proposed model was favorably validated with the offshore measurement of Horns Rev wind farm, and three Taiwanese onshore wind farms were forecasted for their yearly capacity factors with an average error less than 5%, where the required computational cost is estimated about two orders of magnitude smaller than that of the large eddy simulation. However, the proposed model fails to pronouncedly reproduce the individual power difference among wind turbines in the investigated wind farm due to its time-averaging nature.

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“…where G denotes the production of turbulent kinetic energy based on the model proposed in [11] and (c μ , c k , c ε , c 1 , c 2 , c t ) are the constants of the standard k − ε turbulence model [12], which are summarized in Table I. The turbulent viscosity μ t and the turbulent thermal conductivity k t are defined as follows:…”

Section: Governing Equationsmentioning

confidence: 99%

“…With the presence of an electric arc at high temperature inside the plasma torch the electron density inside the entire plasma torch region is estimated from (20) rather than (11) to explicitly satisfy current conservation in space, whereas the ion density is still obtained from the numerical solution of (12)…”

Section: Governing Equationsmentioning

confidence: 99%

Nonequilibrium Modeling of Steam Plasma in a Nontransferred Direct-Current Torch

Chau

Tai

Chen

2014

IEEE Trans. Plasma Sci.

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This paper proposes a magnetohydrodynamic model that does not assume local thermal equilibrium (LTE) to predict the flow field and electron temperature and species density distributions inside a direct-current nontransferred-arc steam torch with a well-type cathode at atmospheric pressure. A steady, axisymmetric flow is assumed, and the azimuthal velocity component is not neglected. A finite volume method is adopted to solve the continuity equation, the current continuity equation, the momentum equation, and the energy equation according to a k − ε turbulence model. Ohm's law is used to calculate the induced magnetic field, and Ampere's circuital law is adopted to compute the current distribution in space. Fifty-two chemical and plasma kinetic equations are employed to describe the interactions among the 12 main species of water plasma, H electrons, considered in this paper. The electron temperature is predicted from the transport equation based on the electron energy balance, whereas the transport coefficients of the plasma are obtained from the Chapman-Enskog solution of the Boltzmann equation. The thermal plasma flow of steam inside the plasma torch, which measures 503 mm in length and 9 mm in radius, is predicted to have I = 180 A and Q = 5 g/s. The non-LTE simulation suggests that a plasma temperature of 11 600 K and flow velocity of 3.8 km/s can be achieved at the center of the torch outlet. Compared with the LTE model, the non-LTE calculation yields lower plasma temperature and higher axial velocity at the torch outlet. The calculated electron temperature principally varies between 1 and 3 eV, and energetic electrons occur not only near the electrode surfaces but also within the axial electric arc. The model predictions suggest that the thermal plasma is well approximated as LTE in the hot plasma core, which is characterized by an isothermal contour of 10 kK, and in the vicinity of the electrodes. The deviation from the LTE condition predominantly grows with the radial coordinate, and the temperature ratio approaches unity at the electrode surfaces. The dominant species components of the water plasma in the inner region (r < 6 mm) at the torch outlet are monoatomic and ionic species of H and O, whereas the diatomic species and water molecule become relatively important in the outer region (r > 6 mm) at the torch outlet.

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Modeling steady axis-symmetric thermal plasma flow of air by a parallelized magneto-hydrodynamic flow solver

Cited by 9 publications

References 14 publications

Plasma discharge characteristics of segmented diverter strips subject to lightning strike

Plasma discharge characteristics of segmented diverter strips subject to lightning strike

Power Prediction of Wind Farms via a Simplified Actuator Disk Model

Nonequilibrium Modeling of Steam Plasma in a Nontransferred Direct-Current Torch

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