Combustion Characteristics and Laminar Flame Speed of Premixed Ethanol-Air Mixtures with Laser-Induced Spark Ignition

Abstract

Laser-induced spark-ignition (LISI) has an advanced ignition technique with a few benefits over spark ignition. In this study, flame morphology, laminar flame characteristics and combustion characteristics of premixed anhydrous ethanol and air mixtures were investigated using LISI generated by a Q-switched Nd: YAG laser (wavelength: 1064 nm). Experiments were conducted in a constant volume combustion chamber (CVCC) at the initial condition of T0=358 K and P0=0.1 MPa, respectively, and with equivalence ratios (ɸ) of 0.6-1.6. Flame images were recorded by using the high-speed Schlieren photography technique, and the in-vessel pressure was recorded using a piezoelectric pressure transducer. Tests were also carried out with spark ignition, and the results were used as a reference. It has been found that the laminar flame speed of ethanol-air mixtures with LISI was comparable with those of spark ignition, proving that ignition methods have no influence on laminar flame speed which is an inherent characteristic of a fuel-air mixture. The peak laminar burning velocities for LISI and spark ignition with nonlinear extrapolation methods were approximately 50 cm/s at ɸ=1.1. However, LISI was able to ignite leaner mixtures than spark ignition. The maximum pressure rise rate of LISI was consistently higher than that of spark ignition at all tested ɸ, although the maximum pressure was similar for LISI and spark ignition. The initial combustion duration and main combustion duration reached the minimum at ɸ=1.1.

Optimization Study of the Ratio of Bioethanol Bioaceton Ron 90 on the Power and Emissions of a 110cc Gasoline Motor

“…Flame propagation is also related to the compression ratio, for example the greater the compression ratio, the higher the flame propagation speed [27]. Thus the use of bioefuels makes it possible to increase the compression ratio in gasoline engines, without the problem of knocking and accelerating flame propagation, on the other hand flame propagation is not affected by the ignition method, which is a characteristic of biofuel-air mixtures [28]. Flame instability also plays a role in performance and emission results.…”

Impact of Multi-Component Surrogates on the Performances, Pollutants, and Exergy of IC Engines

“…In these equations, ∇ denotes the tangential gradient operator, → u is the fluid velocity, → u vertex is the velocity of the moving vertex, while ρ u and ρ b represent the average densities of the unburned and burned mixtures, respectively. The term D T is the turbulent diffusivity, κ is the Favre mean flame front curvature, and C S , a 4 , b 1 , and b 3 are model constants provided in [8,12,35,36]. The quantities k and ε are the Favre mean turbulent kinetic energy and its dissipation rate from the RNG k − ε model, while u is the turbulence velocity fluctuation.…”

“…The quantities k and ε are the Favre mean turbulent kinetic energy and its dissipation rate from the RNG k − ε model, while u is the turbulence velocity fluctuation. The turbulent flame S O T , used in the G-equation, is obtained through the following equation [8,12,35,36]:…”

The development of a new optical method to measure the delay time of spark ignition

“…Among these, rapid compression machines (RCM) [2][3][4][5], shock tubes (ST) [6][7][8][9][10] or both [11][12][13][14][15] are the most widespread. A qualitative description of the self-ignition delay is given in Figure 1 as a plot pressure P or radiation intensity RI in time: The forced ignition, particularly spark ignition, sometimes supplemented with plasma or laser [15][16][17][18][19][20], was frequently studied using constant volume combustion bombs (CVB). The method presented in this paper relies on the analysis of the radiation intensity variation during the early stages of spark ignition in a CVB.…”