Flame kernel evolution and shock wave propagation with laser ignition in ethanol-air mixtures

Bao, Xiuchao; Sahu, Amrit Bikram; Jiang, Yizhaou; Xu, Hongming

doi:10.1016/j.apenergy.2018.10.017

Cited by 19 publications

(8 citation statements)

References 41 publications

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“…The third lobe became more evident with an increment in ϕ, whereas the flame profiles approached a spherical shape with time. Similar flame images were also observed in the research of Bao et al 22 The ignition location shown in Figure 3a is not always consistent. The ignition energy of the fire core area in LISI should reach 10 14 W/mm 2 , but it is difficult to reach such high ignition energy in practice, so the mixture is always ignited because of dust in the mixture near the laser focus point.…”

Section: Resultssupporting

confidence: 80%

“…O'Briant et al 21 proposed the use of laser ignition in aerospace propulsions involving gas turbine applications, and ramjet and space and rocket applications. Bao et al 22 investigated ethanol−air mixtures' flame evolution and shock-wave propagation in a constant-volume combustion vessel using laser ignition (75−200 mJ). It was found that the contraction of the plasma zone was associated with rapid shock-wave propagation.…”

Section: Introductionmentioning

confidence: 99%

“…What is more, the laminar burning velocity of SI obtained by CPM was compared with results reported in the literature to validate the reliability of the experimental results. The laminar burning velocity with LISI can only be calculated through CVM because the three-lobe-shaped flame front appears in LISI, 22 so the radius of the flame front is not easy to determine. The laminar burning velocities of ethanol−air mixtures with SI and LISI obtained by CVM under all conditions were also compared.…”

Section: Introductionmentioning

confidence: 99%

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Laminar Burning Velocity of Premixed Ethanol–Air Mixtures with Laser-Induced Spark Ignition Using the Constant-Volume Method

Wang

Zhou

et al. 2019

Energy Fuels

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Ethanol is a widely used gasoline alternative because of its renewability. Laser-induced spark ignition (LISI) is a promising ignition technique for internal combustion engines because of its advanced lean-burning capability and flexibility in ignition location and energy. However, determining laminar burning velocities of ethanol−air mixtures with LISI is difficult because of its irregular three-lobe flame profile. In this paper, LISI and spark ignition (SI) were used to ignite premixed ethanol−air mixtures in a constant-volume combustion chamber at the initial temperature and pressure of 358 K and 0.1 MPa, respectively. The constant-volume method (CVM), which uses pressure history data as inputs rather than flame images as in the constant-pressure method (CPM), was applied for LISI to overcome the aforementioned issue. Additionally, two chemical kinetic mechanisms were used to obtain simulated laminar burning velocities. When SI is used, laminar burning velocities obtained from the CVM were 1.1−6.3% higher than those from the CPM. This was due to some assumptions made in the CVM. When applying LISI and CVM, the laminar burning velocities were obtained over a wide range of pressures (0.1−0.3 MPa) using extrapolation. As the pressure was extrapolated to two times of the initial pressure (0.2 MPa), the largest and the mean deviations between the laminar burning velocities obtained from the CVM and the simulation were approximately 10 and 5%, respectively. As the pressure was extrapolated to a higher pressure (0.3 MPa), a larger deviation was observed. Therefore, the laminar burning velocities obtained in this study between the initial pressures of 0.1 and 0.2 MPa are reliable.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laminar Burning Velocity of Premixed Ethanol–Air Mixtures with Laser-Induced Spark Ignition Using the Constant-Volume Method

Wang

Zhou

et al. 2019

Energy Fuels

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“…whether the spectral emission at the moment of measurement still truly reflects the local composition. At the same time, the ns laser-induced plasma (LIP) will produce a lasersupported detonation wave [24], which affects the spatial distribution of compositions, making the situation even messier. Furthermore, our group also conducts research on the spatial resolution of ns LIBS [25], and experimentally we prove that firstly, the plasma expands rapidly even after the laser pulse, and accordingly, the ions generated during the laser pulse also expand and produce LIBS signal at the same time; secondly, as the plasma continues to grow after the laser pulse, it will engulf and ionize the surrounding gases, which also contributes to the LIBS signal.…”

Section: Introductionmentioning

confidence: 99%

Direct comparison of ns LIBS and fs LIBS with high spatial and temporal resolution in gases

Feng¹,

Zhang²,

Li³

et al. 2022

J. Phys. D: Appl. Phys.

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Spatial resolution is one of the most critical parameters for spectroscopic measurements especially when used in gases. However, the spatial resolution of femtosecond (fs) laser-induced breakdown spectroscopy (LIBS) in gases has not been thoroughly investigated. Here, we directly compare the differences and connections between ns LIBS and fs LIBS through spatio-temporally resolved spectroscopy. At the time period we measured, unlike the ns LIBS plasma, the fs LIBS plasma does not show detectable expansion, and we do not find composition transport due to turbulence inside the fs LIBS. In other words, the local spectral emission in the fs LIBS can correlate precisely to the composition at that location before the arrival of the laser, while ns LIBS cannot. This feature allows fs LIBS has much higher spatial resolution than ns LIBS. Finally, this paper verified that fs LIBS can be used for one-dimensional measurements capability with its spatial resolution of 50 μm.

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“…Bradley et al [6] studied the laser ignition of gaseous fuels and recorded the development of the flame kernel and the propagation of the shock wave for the first time using a high-speed camera, and analyzed the formation of the third-lobe with gas dynamics theory in detail. Xu et al [7] studied the flame kernel of ethanol/oxygen mixture and compared the difference of velocities in different directions. The rarefaction wave generated by plasma caused the change in gas density gradient and pressure near the plasma, interacts with the high-temperature gas and produces local flow, leading to an annular structure from the left and right sides [6,8,9].…”

Section: Introductionmentioning

confidence: 99%

Shock Wave Propagation and Flame Kernel Morphology in Laser-Induced Plasma Ignition of CH4/O2/N2 Mixture

Zhang

Gao

et al. 2021

Energies

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The application of laser ignition in the aerospace field has promising prospects. Based on the constant volume combustion chamber, the laser ignition of CH4/O2/N2 mixture with different initial pressure, different laser energy, different equivalence ratio and different oxygen content has been carried out. The development characteristics of the flame kernel and shock wave under different conditions are analyzed. In addition, the Taylor model and Jones model are also used to simulate the development process of the shock wave, and a new modified model is proposed based on the Jones model. The experimental results show that under pure oxygen conditions, the chemical reaction rate of the mixture is too fast, which makes it difficult for the flame kernel to form the ring and third-lobe structure. However, the ring structure is easier to form with the pressure and laser energy degraded; the flame kernel morphology is easier to maintain at a rich equivalence ratio, which is caused by the influence of the movement of hot air flow and a clearer boundary between the ring and the third-lobe. The decrease of the initial pressure or the increase of the laser energy leads to the increase in shock wave velocity, while the change of the equivalence ratio and oxygen content has less influence on the shock wave.

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Flame kernel evolution and shock wave propagation with laser ignition in ethanol-air mixtures

Cited by 19 publications

References 41 publications

Laminar Burning Velocity of Premixed Ethanol–Air Mixtures with Laser-Induced Spark Ignition Using the Constant-Volume Method

Laminar Burning Velocity of Premixed Ethanol–Air Mixtures with Laser-Induced Spark Ignition Using the Constant-Volume Method

Direct comparison of ns LIBS and fs LIBS with high spatial and temporal resolution in gases

Shock Wave Propagation and Flame Kernel Morphology in Laser-Induced Plasma Ignition of CH4/O2/N2 Mixture

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