Modules combustor

Potential mechanical problems associated with mechanically variable geometry combustors have promoted studies on various types of aero-dynamically modulated combustors. This modulation of the combustor could, in principle, be controlled by very small control flows introduced or extracted from the chamber of the combustor. Alternatively, it could be inherent in the aerodynamics of the combustor. Flexibility in combustor operation can be obtained easily by small changes in combustor geometry so as to obtain the desired aerodynamic changes within the combustor. It can also be obtained by changing the stoichiometry of the flow. 

A supplementary eompressor (eonsisting of commercial off-the-shelf compressor or standard compressor modules) to provide the supplementary airflow up-stream of combustors. 

Wilson, K. J., E. Gutmark, K.C. Schadow, and R. A. Smith. 1991. Active control of a dump combustor with fuel modulation. AIAA Paper No. 91-0368. 

In the full catalytic burner, all the fuel is processed within an RCL bum module which replaces a conventional premixer-swirler arrangement in the DLN combustor. 

On the other hand, following the development of hybrid combustor configurations that prevent operation of the catalyst module at temperatures above 900-1000 °C, the major drawback of metallic monoliths, namely the limited maximum operating temperature, has been overcome. Accordingly, honeycombs made of metal foils have been adopted in GT catalytic combustors in view of their excellent thermal shock resistance and thermal conductivity properties [9]. In addition, metallic substrates are a promising option for the fabrication of microcombustors. 

Two different descriptions are possible. The simplest approach is the balance border around the complete module including all stacks and the joint burner from the inlet I of the fuel F and the air A to the outlet aB of the flue gas G after the burner. The more detailed approach is a balance border which surrounds all stacks from the inlet I to the outlets O of the anode side AnO and of the cathode side CaO. The calculation of this power generating burner is similar to the calculation of a combustor of a gas turbine or of a furnace of a boiler. The calculation of the mass flows of the module does not differ from any calculation of a conventional oxidation. The energy balance of this simpler approach (from / to aB) gives... 

The study shed new light on the importance of dynamic interaction between flow structures and pulsed sprays in liquid-fueled ACC. The results provided valuable information on the fuel injection timing for desired outcome. In the present case, the fuel injection timing that was synchronized with the air vortex shedding led to the suppression of pressure oscillations. When the fuel injection timing was delayed a quarter cycle after the vortex shedding, combustor pressure oscillations reached the highest amplitude. The scale-up test revealed a critical role of the relative amount of modulated heat release from pulsed fuel injection. 

Potential Application of a Modulated Swirl Combustor to Clean Combustion of Liquid Fuel... 

The modulated swirl combustor decribed here (2) represents a step in this direction when operated with propane or hquid kerosene. It exhibits a very distinct change in flow pattern and potentially can satisfy pollution legislation over a wide operating range of heat release rates, as required, for example, in an aircraft gas turbine engine combustor. 

Modulated Swirl Combustor. The design of the modulated swirl combustor evolved from swirl burners tested by the authors at SheflBeld University and Institute of Flame Research Foundation (IFRF), Ijmuiden (3,4,5,9,10), The modulated swirl combustor (Figure 2) consists essentially of a cyUndrical chamber 1.8 diameters long with an outlet consisting of a contraction followed by a short wide-angle diffuser. Air could be... 

Figure 2, Schematic of the modulated swirl combustor Details of the modulated swirl combustor are as follows ...

It is therefore evident that a detailed experimental analysis of the spray flame is necessary for its theoretical characterization. The aerodynamic changes achieved within the modulated swirl combustor, in which it is demonstrated that blue flame combustion of oil can be achieved using this combustor and a Sonicore atomizing nozzle, clearly show the strong effect of flow aerodynamics upon the spray combustion process. 

Figure 7. Flame photographs obtained from the modulated swirl combustor using propane as the fuel showing no-ring and ring modes of combustion...

The different type of combustion processes obtained from this experimental modulated swirl combustor therefore help in understanding and analyzing the complex flow behavior observed in certain type of industrial flames (13). 

Propane Fuel—Results and Discussion. Onuma (12) showed that in a kerosene spray flame, there is no evidence of droplet burning. The vapor cloud formed by evaporation of the droplets bums like a turbulent diffusion flame. A close relationship between kerosene spray flame and gaseous diffusion flames (using propane as the fuel) was provided. The results reported in this section are those obtained from the modulated swirl combustor using propane as the fuel. 

Figure 8, Stability limits of the modulated swirl combustor. Total air flow = 1070 LI min, equally distributed in the four points of inlets.

Figure 9. Boundaries of the internal recirculation region in the modulated swirl combustor—propane fuel...

Kerosene Fuel—Results and Discussion. Liquid kerosene was burned in the above modulated swirl combustor using a Sonicore atomizing nozzle. As expected the flame could be modulated to obtain a bright yellow, highly radiative flame or a clean blue flame as shown in Figure 12. Total air flow was the same, and the bum-out was complete by about 1 diameter downstream of the burner exit in both cases. Radial distribu-... 

The modulated swirl combustor presented here has generally stable and acceptable basic characteristics, but in addition, it has two modes of... 

Figure 12, Flame photographs of the kersosene-air flame using sonicore atomizer and the modulated swirl combustor, (a) Bright yellow, highly radiative flame (b) clean, blue flame.

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