Flames high momentum

If high-momentum oxy/fuel burners are used, the wall opposing the burner may overheat and damage may occur to the refractory.2 To minimize this problem, low-momentum burners are recommended. Overheating can still occur with low-momentum burners if the flame impinges on the opposite wall. In this case, the firing rate must be reduced. 

Gollahalli, Brzustowski, and Sullivan [2] measured the size and centerline trajectories of TDFCF in high momentum flux ratios. Figure 29.8 presents the normalized flame width and thickness measured normal to the visible centerline at various downstream locations. After the jet was discharged into the crossflow stream, there was an initial sudden raise in the flame thickness due to the initiation of combustion process (see insert Figure 29.8a). The cross section continued to increase as the entrainment of air and combustion of pyrolyzed fuel components occurred downstream. After some point downstream, the rate of combustion decreased, which in turn decreased the cross-sectional dimension. 

Fig. 3.27. Scrap preheater with high-momentum flames driving through the interstices of iron scrap, to preheat it prior to big ladie melting, and to incinerate paint and oil on the scrap.

Experience has shown that for a confined flame, sufficient primary air jet momentum is required to create mixing via external recirculation zones. As the acid-alkali model shows, high momentum and, for that matter, intense and perhaps complete mixing, is tantamount to efficient combustion. We discussed in Chapter 4 that, for confined jets, the onset of flame recirculation can be described by the Craya-Curtet... 

Detonation Momentum Attenuator A mechanical device inside of a detonation flame arrester whose pnrpose is to rednce both the high pressnre and the dynamic energy of a detonation and to split the flame front before it reaches the actnal flame arrester element, thns avoiding stmctnral damage to the element. (This device is also called a shock absorber device by some mannfactnrers.)... 

Furthermore, we will take all other properties as constant and independent of temperature. Due to the high temperatures expected, these assumptions will not lead to accurate quantitative results unless we ultimately make some adjustments later. However, the solution to this stagnant layer with only pure conduction diffusion will display the correct features of a diffusion flame. Aspects of the solution can be taken as a guide and to give insight into the dynamics and interaction of fluid transport and combustion, even in complex turbulent unsteady flows. Incidentally, the conservation of momentum is implicitly used in the stagnant layer model since ... 

Turbulent jet diflFusion flames. In this case, the oil is atomized by high-pressure air or steam (air blast atomizer), and the momentum of the fuel spray is so high that the entrained air is suflBcient to complete the combustion. 

Since the TAB is in the order of magnitude of 1 x 10 , one would expect that the flame would be highly turbulent and momentum-dominated. 

High Jet-to-Crossflow Momentum Flux Ratio Flames... 

In case of a leakage from a high pressure pipeline the usual relationships for flame dimensions of Sect. 10.6.1.1 cannot be applied, since they are only valid for pool fires (low initial momentum). 

Currently, one of the most developed, hence most illustrative, examples of practical application of SM is provided by the GRI-Mech project [1]. In its latest release, the GRI-Mech 3.0 dataset is comprised of 53 chemical species and 325 chemical reactions (with a combined set of 102 active variables), and 77 peer-reviewed, well-documented, widely trusted experimental observations obtained in high-quality laboratory measurements, carried out under different physical manifestations and different conditions (such as temperature, pressure, mixture composition, and reactor conhguration). The experiments have relatively simple geometry, leading to reliably modeled transport of mass, energy, and momentum. Typical experiments involve flow-tube reactors, stirred reactors, shock tubes, and laminar premixed flames, with outcomes such as ignition delay, flame speed, and various species concentration properties (location of a peak, peak value, relative peaks, etc.). 

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