Gas premixed combustion at high turbulence. Turbulent flame closure combustion model

Abstract

This paper is devoted to analyze the special class of turbulent premixed ames that we call intermediate steady propagation (ISP) ames. These ames are common to industrial premixed combustion chambers which operate at intensive turbulence when velocity pulsations are signi cantly higher than the amelet combustion velocity. They are characterized by a practically constant turbulent combustion velocity, controlled by turbulence, chemistry and molecular processes, and by an increasing ame width, controlled mainly by turbulent di usion.The main content of this work is a description of physical backgrounds and outcome of the original asymptotical (i.e., valid at high Re and Da numbers) premixed combustion model, that, from a methodological point of view, is close to Kolmogorov analysis of developed turbulence at high Re numbers. Our analysis starts from the thickened and strongly wrinkled amelets combustion mechanism. Quantitative results for this model are based on the Kolmogorov assumption of the equilibrium ne-scale turbulence and on additional assumption of the universal small-scale structure of the wrinkled amelet sheet. From this background it is possible to deduce formulas for the thickened amelets parameters and the amelet sheet area and hence the turbulent combustion velocity of the premixed ame. These formulas are used for the closure of the combustion equation written in terms of a progress variable leading to the so called turbulent ame closure (TFC) model for the numerical simulation of ISP ames. Consistent to the ISP ames, in this work the concept of countergradient transport phenomenon in premixed combustion is analyzed.

A combined experimental and numerical study of thermal processes, performance and nitric oxide emissions in a hydrogen-fueled spark-ignition engine

“…In the developed combustion model the turbulent flame speed (u t ) is used, in order to track the computational cells in which the flame has propagated during the main stages of combustion after the ignition phase. The expression incorporated is the one proposed by Zimont/Lipatnikov and Chomiak [28,29], where only one calibration constant "A" needs to be tuned. This tuning process has been accomplished in the evaluation study of the combustion model [16], where the calibration constant has been found to be equal to 0.8.…”

Burning Rate in Impinging Jet Flames

“…To the the best of the present author's knowledge, the key equation of the extended Zimont model, that is, (19), has yet been substantiated by basic arguments [3,28,29,32,34,38] only in the case of a statistically planar one-dimensional premixed turbulent flame. Therefore, strictly speaking, the extended Zimont model yields the following joint closure:…”

“…The approximate equality of u t and |w e (z f )| may further be supported by invoking the so-called Zimont [32][33][34] Stevens et al [18], set 1 Stevens et al [18], set 2 Stevens et al [18], set 3 (c) Figure 2: Axial profiles of (a) the Reynolds-averaged combustion progress variable c(x), measured by Cho et al [15] and by Cheng and Shepherd [16], and the Favre-averaged combustion progress variable c(z), measured (b) by Li et al [17] and (c) by Stevens et al [18]. Symbols show experimental data.…”

Composition and Stoichiometry Effects of Biogas as Fuel in Spark Ignition Engine

“…We employ the method of probability density function (PDF) to detect the mixture fraction and to model chemistry in the system (used for cases of premixed and non-premixed combustion). The Zimont model of the turbulent flame speed is used to enclose the turbulent quantities, typically used for cases of premixed combustion [28]. The non-premixed model of combustion solves transport equations for conserved scalar and mixture fractions.…”