Introductory Chapter: Swirling Flows and Flames

Abstract

Swirling flows are used in a very wide range of industrial applications. In non-reacting cases, examples of applications include vortex amplifiers and reactors, heat exchangers, jet pumps, cyclone separators, whirlpools, tornadoes, etc. In reacting cases, swirlers are widely used in combustion systems, such as gas turbines, industrial furnaces, boilers, gasoline and diesel engines and many other practical heating devices. Effects of using swirl on flow and combustion are significant and various and concern, for example, aerodynamics, mixing, flame stability, intensity of combustion and pollutant emissions. In this chapter, we are interested in the use of swirling flows in combustion systems. In industrial plants, the geometric methods of flame stabilization are based on increasing the residence time of reactive gases either by the wake effect bluff-body burner, by the flow rotation of reactants swirl burner or by a combination of these two mechanisms. Burners with helical flows generally referred to as the swirl burner have very wide applications in the industrial field. In the literature, many examples of uses of swirling jets are found as a means of controlling combustion [1-4]. Other studies focused on the swirl effect on the characteristics of lifted flames [5], stabilization and blow-out phenomenon [6-8] and pollutant emissions [9-13]. 2. Swirl generation techniques There are several ways to generate the rotation of a flow. They can be classified into three main categories:

Analysis of Highly CO2-Diluted Oxy-propane Flames Stabilized over a Multihole Burner of a Model Gas Turbine Combustor

“…This variation in mean and maximum outlet temperatures is due to heat loss through the quartz wall by means of both convection and radiation heat transfer. Furthermore, the swirl effect allows increases in residence time and reduction in flame temperature as reported in earlier studies. , …”

“…Furthermore, the swirl effect allows increases in residence time and reduction in flame temperature as reported in earlier studies. 42 , 43 …”

Simulação numérica de um escoamento turbulento não-reativo no interior de uma caldeira ciclônica industrial usando LES e URANS

“…One of them is to use propellers tangentially deflecting the axial flow, which are simple devices used in industrial systems but may introduce head losses and the intensity of the swirl is limited. Another way is to use rotating mechanical devices to employ rotational movement to the fluid passing through them(BOUSHAKI, 2019). At last, tangential injection of fluid by ducts with some differences in their angles might cause a swirl generation at the center of equipment, such as the industrial boiler studied in this research.Swirl flows result from the application of a tangential velocity component imparted to the flow by swirl vanes, by the use of axial-plus-tangential entry swirl generators, or by direct tangential entry.…”