A thermodynamic model for the plasma kernel volume and temperature resulting from spark discharge at high pressures

Meyer, Georg; Wimmer, Andreas

doi:10.1007/s10973-018-7169-z

Cited by 6 publications

(1 citation statement)

References 24 publications

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“…This was already noted by Ko et al [29], who proposed a much more reasoned set of initial conditions based on previous solutions of cylindrical shockwave equations that allow for a mass increase in the activated plasma volume. This solution has been expanded on by Meyer and Wimmer [32] to include the use of air plasma properties for better estimating the post-cooldown temperature 𝑇 𝑖 , and it requires solving three relatively simple equations: { 𝑟 𝑖,𝑐𝑦𝑙 = 0.5𝑟 𝑐 = 0. Using the present method and 𝜂 𝑏𝑑 ≅ 1 (see Section 3), for air at the same conditions as above the results are 𝑟 𝑖,𝑐𝑦𝑙 = 0.825 mm, 𝑡 𝑖 = 7.12 μs, and 𝑇 𝑖 = 6,139 K, all of which fully consistent with heat diffusion models but stemming from a much sounder procedure.…”

Section: Initial Conditions: the Breakdown Modelmentioning

confidence: 99%

A phenomenological model for predicting the early development of the flame kernel in spark-ignition engines

Giannattasio,

Pretto,

Betta

2023

J. Phys.: Conf. Ser.

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This work presents a simple and effective phenomenological model for the prediction of the early growth of the flame kernel in SI engines, including its initiation as a result of the electrical breakdown of the fuel/air mixture between the spark plug electrodes. The present model aims to provide an improved description of the ignition-affected early phases of flame kernel development compared to the majority of models currently available in literature. In particular, these models focus on electrical energy supply and turbulence, whereas the stretch-induced kernel growth slowdown is quantified with linear models that are inconsistent with the small kernel radius. For the flame kernel initiation, this model replaces the current methods that rely on 1D heat diffusion within a plasma column with a more consistent analysis of post-breakdown conditions. Concerning the kernel growth, the present model couples the mass and energy conservation equations of a spherical kernel with the species and temperature profiles outside of it. This combination leads to a non-linear description of the flame stretch, according to which the kernel development is controlled by the Lewis-number-dependent balance between the heat gained via combustion and the heat lost via thermal diffusion. As a result, the kernel temperature differs from the adiabatic flame temperature, causing the laminar flame speed to change from its adiabatic value and ultimately affecting the overall kernel development. Kernel growth predictions are conducted for laminar flames and compared to literature data, showing a satisfactory agreement and highlighting the ability to describe the stretch-induced kernel slowdown, up to its possible extinction. A good agreement with literature data is also obtained for kernel expansions under moderately turbulent conditions, typical of internal combustion engines. The simple formulation of the present model enables swift integration into phenomenological combustion models for sparkignition engines, while simultaneously offering useful insight into the early kernel development even for CFD-based approaches.

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Section: Initial Conditions: the Breakdown Modelmentioning

confidence: 99%