Premixed flame engine

The interest of studying turbulent premixed flames for modern gas turbines and jet engine afterburners... 

Partial premixing has been proposed as a means of NOj, reduction in gas turbine engines by Jayavant Gore at Purdue University. An experimental and computational study was conducted to observe NO behavior under the circumstances of moderate stretch rate, opposed-flow, partially premixed flames. The results show that the minimum NO emissions at an optimal level of partial premixing result as a consequence of decrease in CH radical concentrations. Partial premixing appears to be a possible practical immediate solution for NO remediation in gas turbines. 

J. Abraham, F. V. Bracco, and R. D. Reitz. Comparisons of computed and measured premixed charge engine cmnbustion. Combust. Flame, 60 309-322, 1985. 

J. Abraham, RA. Williams, and RV. Bracco 1985, A discussion of turbulent flame structure in premixed charge, SAE Paper 850343, in Engine Combustion Analysis New Approaches, p. 156. 

The development of models for HCSI combustion has been governed by the similarity of flame growth in HCSI engines and premixed turbulent flames. Thin laser-sheets of only 300 pm thickness were used to measure high-resolution cross sections of the temperature and OH radical distribution in flames of a propane-fueled engine. Figure 8.2.3 illustrates the structure where temperature and OH concentration are closely coupled with super equilibrium values for the OH radical close to the flame front [11]. 

The rapid-bum phase of SCSI engine combustion is a combination of both premixed and diffusion combustion. As in the HCSl engine, a typical premixed turbulent flame front propagates across the cylinder, originating from the spark plug. This phase tends to occur faster... 

Beyler, C., Flammability limits of premixed and diffusion flames, in The SFPE Handbook of Fire Protection Engineering, 2nd edn (eds P.J. Di Nenno et al.). Section 2, Chapter 9, National Fire Protection Association, Quiney, Massachusetts, 1995, p. 2-154. 

As the important effect of temperature on NO formation is discussed in the following sections, it is useful to remember that flame structure can play a most significant role in determining the overall NOx emitted. For premixed systems like those obtained on Bunsen and flat flame burners and almost obtained in carbureted spark-ignition engines, the temperature, and hence the mixture ratio, is the prime parameter in determining the quantities of NOx formed. Ideally, as in equilibrium systems, the NO formation should peak at the stoichiometric value and decline on both the fuel-rich and fuel-lean sides, just as the temperature does. Actually, because of kinetic (nonequilibrium) effects, the peak is found somewhat on the lean (oxygen-rich) side of stoichiometric. 

J. Abraham, F. A. Williams and F. V. Bracco, A Discussion of Turbulent Flame Structure in Premixed Charges, SAE Paper 850345, Society of Automotive Engineers, Detroit, 1985. 

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