Premixed Flame Propagation and Morphology in a Constant Volume Combustion Chamber

Abstract

This work presents an experimental and numerical investigation of premixed flame propagation in a constant volume rectangular channel with an aspect ratio of six (6) that serves as a combustion chamber. Ignition is followed by an accelerating cusped finger-shaped flame-front. A deceleration of the flame is followed by the formation of a "tulip"-shaped flame-front. Eventually, the flame is extinguished when it collides with the cold wall on the opposite channel end. Numerical computations are performed to understand the influence of pressure waves, instabilities, and flow field effects causing changes to the flame structure and morphology. The transient 2D numerical simulation results are compared with transient 3D experimental results. Issues discussed are the appearance of oscillatory motions along the flame front and the influences of gravity on flame structure. An explanation is provided for the formation of the "tulip" shape of the premixed flame front.

Structure and Propagation of Premixed Flames in a Closed Combustion Chamber with Multiple Ignition Sources

“…These cusp-shaped "tulip" flames maintain their shapes as they propagate towards each other until they finally meet at the center of the channel (Figure 2f) where they annihilate one another, see Wichman and Vance (1997). The structural evolution occurring during CV combustion in the 2-spark configuration is very similar to that observed in the single spark ignition, as described in Hariharan and Wichman (2014). We now discuss some of the details of this combustion process.…”

“…Various explanations for the formation of tulip flames have been hypothesized, such as Darrieus-Landau and Taylor Instabilities by Clanet and Searby (1996), Gonzales et al (1992), N'Konga et al (1993), Matalon and McGreevy (1994), and Dold and Joulin (1995). The work of Hariharan and Wichman (2014) shed light on this explanation. The interaction of the propagating flame front with its numerous, discrete, self-generated pressure waves was studied by Guenoche (1964).…”

“…The research described in this article is a continuation of previous research that analyzed the propagation of laminar flames in a constant volume (CV) combustor (Hariharan and Wichman, 2014). The practical motivation of our original research was to study premixed flame propagation inside a wave disk engine, which employs isentropic compression followed by CV combustion.…”

“…The practical motivation of our original research was to study premixed flame propagation inside a wave disk engine, which employs isentropic compression followed by CV combustion. A detailed explanation of the wave disk engine design and its thermodynamic cycle is provided in Iancu et al (2008), Piechna (2006), Vagani (2009), Iancu et al (2005), Piechna et al (2004), and Hariharan and Wichman (2014); see also the references therein for older work. An experimental investigation of Michigan State University's wave engine prototype revealed unambiguously that combustion was by far the lengthiest process in the cycle.…”

“…Recently, Kiran et al (2014) performed a detailed numerical diagnostics analysis of the influence of the vorticity content in the CV chamber on the flame front behavior. In recent research, the interaction of singular points in the fluid flow near the flame front have been examined in detail experimentally and numerically by Hariharan and Wichman (2014) and experimentally by Ponizy et al (2014) using flow visualization diagnostic methods.…”