Large eddy simulation on combustion noise in a non-premixed turbulent free flame: Effect of oxygen enhancement

Abstract

Present work examines the effect of a low-level oxygen concentration enhancement in the oxidizer stream, on the generation of direct combustion noise in a non-premixed turbulent free flame. A hybrid approach utilizing a large eddy simulation, partially stirred reactor combustion model, and Lighthill analogy was employed to predict the sound pressure level in the farfield of the flame. Contributions of different noise sources, including heat release rate and, mole consumption and production rate fluctuations are calculated to predict the sound pressure level in the farfield.Results show that, in comparison to the flame burning with air, the higher temperature in oxygen enhanced flame leads to an increase in the heat release rate and an increase in the rate of consumption and production of the species. The total sound pressure level found to increase by adding oxygen to the oxidizer stream, especially in low frequency ranges. Enhancement of molar oxygen by 10%, increases the noise contribution of the heat release rate fluctuations about 20 dB in low frequency range, and about 10 dB in high frequencies. Additionally, the noise contribution from the mole consumption and production rate decreases about 5 dB in low frequency range and 10 dB in high frequencies.

Numerical study of the effect of ultrasound waves on the turbulent flow with chemical reaction in the combustion chamber

“…Where V is the velocity vector of the acoustic particles, αABS is the acoustic absorption coefficient, P is the acoustic pressure, and I is the acoustic acceleration. The solution is an infinite series represented by Equation (14).…”

“…The oxygen combustion process drastically reduces the chamber's temperature compared to combustion with air. Ehsaniderakhshan et al [14] showed the effect of increasing the concentration of oxygen in a non-premixed turbulent flow on a low-level scale in the oxidizing stream on the production of direct combustion sound. They used a hybrid method using a large vortex simulation in the agitation reactor combustion model and the Lighthill analogy.…”

Explosion behaviors of IPN/air mixture at high temperature and high pressure

“…The leaked combustible liquid fuel was exposed to the high-temperature and high-pressure environment produced by the first explosion, which brought about a second explosion that would also follow the adjacent units, thus forming the domino effect (Chen et al , 2020). In an actual industrial environment, almost all combustion systems are carried out under turbulent flow conditions, that is, the fuel and oxidant react in a turbulent state (Cuenot et al , 2021; Ehsaniderakhshan et al , 2020). In industrial explosions, chain explosions are usually caused by turbulent conditions and high-temperature environments (Bai et al , 2020b; Chang et al , 2020), as reflected in the Tianjin Port accident on August 12, 2015.…”