Turbulent flames nonpremixed

Relevance of Nonpremixed Edge Flames to Turbulent Flames.62... 

In this burner configuration, fuel is injected directly into the combustion chamber and hence, one would initially categorize it as a nonpremixed burner. However, the overall combustion process is quite complex and involves features of nonpremixed, partially premixed, and stratified combustion, as well as the possibility that the autoignition of hot mixtures of fuel, air, and recirculated combushon products may play a role in stabilizing the flame. Thus, while one may start from simple concepts of nonpremixed turbulent flames, the inclusion of local exhnchon or flame lift-off quickly increases the physical and computational complexity of flames that begin with nonpremixed streams of fuel and oxidizer. 

Figure 1.1 shows the axial variation in sound pressure and level for flames (top) and air jets (bottom) as a function of axial distance from burner exit, normalized by the burner diameter (D = 0.8 cm). The nonpremixed turbulent flame levels are between 20 and 30 dB greater than those for the cold jets. A careful observation of the changes in directivity shows that the sound... 

Masri, A.R., Dibble, R.W., and Barlow, R.S., The structure of turbulent nonpremixed flames revealed by Raman-Rayleigh-LIF measurements. Prog. Energy Combust. Sci., 22,307,1996. 

The relevance of nonpremixed edge flames to turbulent nonpremixed flames can be described in two aspects. One is the mechanism of turbulent nonpremixed lifted flames and the other, the flame-hole dynamics. For turbulent lifted flames in nonpremixed jets, the liftoff height is linearly dependent on jet velocity. There have... 

The relevance of premixed edge flames to turbulent premixed flames can also be understood in parallel to the nonpremixed cases. In the laminar flamelet regime, turbulent premixed flames can be viewed as an ensemble of premixed flamelets, in which the premixed edge flames can have quenching holes by local high strain-rate or preferential diffusion, corresponding to the broken sheet regime [58]. 

Temporal sequence of OH-LIF measurements captures a localized extinction event in a turbulent nonpremixed CH4/H2/N2 jet flame (Re 20,000) as a vortex perturbs the reaction zone. The time between frames is 125 ps. The velocity field from PIV measurements is superimposed on the second frame and has the mean vertical velocity of 9m/s subtracted. (From Hult, J. et al.. Paper No. 26-2, in 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 2000. With permission.)... 

Turbulent nonpremixed flames contain a wide range of lengfh scales. For a given flame geomefry, fhe largest scales of furbulence are determined by the overall width of an unconfined jef flame or by fhe dimensions of the hardware that contain the flow. Therefore, the largest scales of turbulent motion are typically independent of Reynolds number. As the Re5molds number increases. 

Barlow, R. S., Editor International workshop on measurement and computation of turbulent nonpremixed flames in http //www.ca.sandia.gov/TNE... 

Vervisch, L., R. Hauguel, R. Domingo, and M. Rullaud, Three facets of turbulent combustion modelling DNS of premixed V-flame, LES of lifted nonpremixed flame and RANS of jet flame. /. Turbulence, 2004. 5(4) 004. 

Barlow, R. S., R. W. Dibble, J.-Y. Chen, and R. P. Lucht (1990). Effect of Damkohler number on superequilibrium OH concentration in turbulent nonpremixed jet flames. Combustion and Flame 82, 235-251. 

Chen, J. Y. and W. Kollmann (1988). PDF modeling of chemical nonequilibrium effects in turbulent nonpremixed hydrocarbon flames. In Twenty-second Symposium (International) on Combustion, pp. 645-653. Pittsburgh, PA The Combustion Institute. 

Chen, J. Y., W. Kollmann, and R. W. Dibble (1989). PDF modeling of turbulent nonpremixed methane jet flames. Combustion Science and Technology 64, 315-346. 

Correa, S. M., A. Gulati, and S. B. Pope (1994). Raman measurements and joint pdf modeling of a nonpremixed bluff-body-stabilized methane flame. In Twenty-fifth International Symposium on Combustion, pp. 1167-1173. Pittsburgh, PA The Combustion Institute. Corrsin, S. (1951a). The decay of isotropic temperature fluctuations in an isotropic turbulence. Journal of Aeronautical Science 18,417 -23. 

Pdf modeling of finite-rate chemistry effects in turbulent nonpremixed jet flames. 

Masri, A. R. and S. B. Pope (1990). PDF calculations of piloted turbulent nonpremixed flames of methane. Combustion and Flame 81, 13-29. 

Comparison of mixing model performance for nonpremixed turbulent reactive flow. Combustion and Flame 117, 732-754. 

PDF calculations of turbulent nonpremixed flames with local extinction. Combustion and Flame 123, 281-307. 

DesJardin, P. E. 1998. Large eddy simulation of strongly radiating nonpremixed turbulent jet flames. Ph.D. Thesis. School of Mechanical Engineering, Purdue University, West Lafayette, IN. 

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