OCR Text |
Show 3 difference here is that, through burner design, a significant such flow is induced into the fuel and/or oxidant jets before they meet and mix to form the main combustion zones. Thus fuel and/or oxidant are both significantly diluted with recirculating products prior to their direct mixing and main reaction, lowering reactant concentration levels within combustion zone and, most importantly, because these products have lost heat, depressing reaction temperatures. In addition, the air is highly preheated, which leads to the stable combustion with small amount of oxygen. In the diesel engines, injected fuel is subjected to the high temperature and high pressure and flame propagation is important phenomenon to be studied. Therefore, numerical [6,7], and experimental studies [8] have been performed. However, as for fundamental aspects of combustion in the highly preheated surrounding air, is still unclear. In the present study, the extinction mechanism of the nonpremixed flames by strain rate and NOx formation in the flame are investigated. 2. EXPRIMENTAL APPARATUS 2.1 Experimental Setup Figure 1 shows the experimental set up. The experiment was performed using a rectangular combustion chamber of 30 mm x 120 mm cross section and an uncooled porous cylinder (sintered bronze) 16 mm in diameter and 30 mm in length. The air was supplied from a blower through an orifice, 8 ceramics honeycomb regenerators of 100 mm x 100 mm x 50 mm, which were heated by premixed burner inserted just upstream of the regenerator. The regenerator components were made of aluminum-titarate. Air stream was heated by this regenerator up to the desired temperature. Downstream of regenerator, the heated air was accelerated by the converging nozzle to the combustion chamber mounted vertically. The insides of the settling chamber and nozzle were coated with ceramics fiber to eliminate heat loss. In the settling chamber, ceramics balls and fine mesh wire gauzes were install to break down the large-scale disturbance. The air |