A Model for Calculating Heat Release in Premixed Turbulent Flames

Schmid, Hans‐Peter; Habisreuther, Peter; Leuckel, Wolfgang

doi:10.1016/s0010-2180(97)00193-4

Cited by 100 publications

(43 citation statements)

References 18 publications

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“…To account for a change of combustion regime, the mean heat release rate model by Schmid et al 25 is used as it explicitly includes the Damköhler number Da,…”

Section: Iic Spectral Model For Heat Release Ratementioning

confidence: 99%

Prediction of Combustion Noise for an Aeroengine Combustor

Liu

Dowling²,

Swaminathan³

et al. 2014

Journal of Propulsion and Power

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Combustion noise may become an important noise source for lean-burn gas turbine engines, and this noise is usually associated with highly unsteady flames. This work aims to compute the broadband combustion noise spectrum for a realistic aeroengine combustor, and to compare with available measured noise data on a demonstrator aeroengine.A low-order linear network model is applied to a demonstrator engine combustor to obtain the transfer function that relates to unsteadiness in the rate of heat release, acoustic, entropic and vortical fluctuations. A spectral model is used for the heat release rate fluctuation, which is the source of the noise. The mean flow of the aeroengine combustor required as input data to this spectral model is obtained from RANS simulations. The computed acoustic field for a low-medium power setting indicates that the models used in this study capture the main characteristics of the broadband spectral shape of combustion noise. Reasonable agreement with the measured spectral level is achieved.

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“…To account for a change of combustion regime, the mean heat release rate model by Schmid et al 25 is used as it explicitly includes the Damköhler number Da,…”

Section: Iic Spectral Model For Heat Release Ratementioning

confidence: 99%

Prediction of Combustion Noise for an Aeroengine Combustor

Liu

Dowling²,

Swaminathan³

et al. 2014

Journal of Propulsion and Power

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“…The first one is responsible for the correct evaluation of the turbulent flame speed in the current local conditions, while the second one provides the flame propagation in the simulated media with the evaluated speed. Based on the results from the reference (Yanez, 2010), the correlation for the evaluation of turbulent burning velocity proposed by Schmidt (1998) Further examination of the experimental observations disclosed the fact that the test under consideration was differed from the others by considerable sound effect. This can be seen at the pressure history in Figure 4.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Hydrogen deflagration simulations under typical containment conditions for nuclear safety

Yáñez

Kotchourko

Lelyakin

2012

Nuclear Engineering and Design

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This paper presents the modeling of low-concentration hydrogen deflagrations performed with the recently developed KYLCOM model. Three experiments carried out in THAI facility (performed in the frames of international OECD THAI experimental program) were selected for the simulation exercise. The tests allow studying lean mixture hydrogen combustion at normal ambient, elevated temperature and superheated and saturated conditions. The experimental conditions considered together with the facility size and shape grant a high relevance degree to the typical NPP containment conditions. The results of the simulations were thoroughly compared with the experimental data, and the comparison was supplemented by the analysis of the combustion regimes taking place in the considered tests. Results of the analysis demonstrated that despite the comparatively small difference in mixture properties, three different combustion regimes can be definitely identified. INTRODUCTIONThe THAI experimental containment research program has been extensively used in code validation activities (Clement, 2007). On the basis of the delivered data, the physical models for the description of complicated distribution and combustion phenomena applicable in accidental conditions in nuclear power plants (NPP), were improved and developed. Several areas of interest for nuclear reactor containment applications were studied. Extensive test program concerning thermal hydraulics, hydrogen distribution and combustion, aerosol and iodine (fission products) behavior have been conducted.As a part the licensing process of the reactor containment, the threat of uncontrolled hydrogen release and combustion must be addressed. The state-of-the-art mitigation systems can reduce significantly the risk of such an accident. Nevertheless, under severe circumstances, scenarios consisting of low H 2 concentration deflagration processes must be assessed.The general objective of the study reported in the current paper is to address hydrogen deflagrations in lean mixtures with vertical flame propagation. The selected conditions can be considered as close to those typical under accidental situation in NPP; among them, the size and shape of the facility, the elevated initial temperature, pressure, and steam concentrations. EXPERIMENTSThe main component of the THAI facility is the cylindrical steel vessel of 9.2 m height and 3.2 m diameter, with a total volume of 60 m³ depicted in Figure 1. At the lower end of the container a sump compartment is attached. Cooling/heating jackets, subdivided in three vertical sections, were set up in the outer cylindrical wall. The entire vessel was thermally insulated with a double-wall, being the inner wall 22 mm thick and the outer wall made from 6-mm stainless steel. The 16.5-mm gap between the walls is filled with thermal oil. The outside wall is insulated by the 120-mm Rockwool layer.Fifteen continuously operating lines took gas samples from the vessel atmosphere at different locations (see Figure 1 left) prior and after hydrogen c...

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“…For the test discussed here, the most important feature of the currently available algebraic models consists of the fact that the function and the time Bray [31] Bailly et al [32] Schmidt et al [33] Lindstedt and Váos [34] Swaminathan and Bray [35] % % c c…”

Section: Algebraic Modelsmentioning

confidence: 99%

“…Since τ Σ , υ Σ , and U c do not depend directly on t and x in the case of statistically stationary and spatially uniform turbulence discussed here, integration of eqn (29) yields (30) because . If we introduce the following length scale (30) reads (32) If we assume that the turbulent burning velocity tends to a time-independent fullydeveloped value U t, ∞ with time, then, at t → ∞, eqn (32) reduces to (33) Using this fully-developed length scale, the fully-developed turbulent burning velocity, and the time scale τ Σ in order to normalize eqn (32), we finally obtain (34) where t′ = t/τ Σ , u t = U t /U t, ∞ and λ t = Λ t /Λ t, ∞ . Equation (34) shows that the turbulent burning velocity grows only if the normalized velocity u t is lower than the normalized length scale λ t .…”

Section: An Analytical Testmentioning

confidence: 99%

Testing Premixed Turbulent Combustion Models by Studying Flame Dynamics

Lipatnikov

2009

International Journal of Spray and Combustion Dynamics

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First, the following universal feature of premixed turbulent flame dynamics is highlighted: During an early stage of flame development, the burning velocity grows much faster than the mean flame brush thickness, because the two processes are controlled by the small-scale and large-scale turbulent eddies, respectively. Second, this feature of developing flames is exploited in order to test a number of different models of premixed turbulent combustion by theoretically and numerically studying an interaction of an initially laminar, planar, one-dimensional flame with a statistically stationary, planar, one-dimensional, and spatially uniform turbulent flow not affected by combustion. To test as many models as possible in a simple and unified manner, various combustion models are divided into three generalized groups: (i) algebraic models, which invoke an algebraic expression for the mean rate of product creation, (ii) gradient models, which involve a gradient-type source term in a balance equation for the mean combustion progress variable, and (iii) two-equation models, which deal not only with a balance equation for the mean combustion progress variable but also with either a balance equation for the flame surface density or a balance equation for the mean scalar dissipation rate. Analytical and numerical results reported in the paper indicate that solely the gradient models are able to yield substantially different growth rates of the turbulent burning velocity and the mean flame brush thickness.

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A Model for Calculating Heat Release in Premixed Turbulent Flames

Cited by 100 publications

References 18 publications

Prediction of Combustion Noise for an Aeroengine Combustor

Prediction of Combustion Noise for an Aeroengine Combustor

Hydrogen deflagration simulations under typical containment conditions for nuclear safety

Testing Premixed Turbulent Combustion Models by Studying Flame Dynamics

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