Elastic breakdown via multi-core high frequency discharge for lean-burn ignition

2021 ◽  
pp. 095440702110622
Author(s):  
Xiaoye Han ◽  
Xiao Yu ◽  
Hua Zhu ◽  
Linyan Wang ◽  
Shui Yu ◽  
...  
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Imaging Techniques ◽  
Ignition Process ◽  
High Speed Imaging ◽  
Lean Burn ◽  
Electric Circuits ◽  
High Frequency Discharge ◽  
Breakdown Process ◽  
Ignition Quality

An advanced ignition technique is developed to achieve multi-event breakdown and multi-site ignition using a single coil for ignition quality improvements. The igniter enables a unique elastic breakdown process embracing a series of high-frequency discharge events at the spark gap. The equivalent electric circuits and current/voltage equations are identified and verified for the first time to explain the working principle that governs such an elastic breakdown process. Benchmarking tests are first performed to compare the elastic breakdown ignition with the conventional and advanced multi-electrode ignition systems. The elastic breakdown and spark events are thereafter analyzed through current and voltage measurements and high-speed imaging techniques. Finally, ignition tests in combustion chambers are performed to examine the effects on the ignition process in comparison with conventional coil-based ignition systems. The experiments show that, the elastic breakdown ignition can distribute multiple high-frequency breakdown events at all electrode pairs of a multi-electrode sparkplug while using only one ignition coil, thereby offering significant cost saving advantage and packaging practicability.

High Speed Imaging Techniques For Pulse Nuclear Radiation Source

1989 ◽  
Author(s):  
Wang Kuilu ◽  
Lu Ming ◽  
Liu Cunfu ◽  
Kang Dechun
Keyword(s):  
Radiation Source ◽  
High Speed ◽  
Imaging Techniques ◽  
Nuclear Radiation ◽  
High Speed Imaging

Visualizing an ignition process of hydrogen jets containing sodium mist by high-speed imaging

2019 ◽  
Vol 56 (6) ◽  
pp. 521-532
Author(s):  
Daisuke Doi ◽  
Hiroshi Seino ◽  
Shinya Miyahara ◽  
Masayoshi Uno
Keyword(s):  
High Speed ◽  
Ignition Process ◽  
High Speed Imaging

Special high speed imaging techniques using phase, aperture, and polarization effects

2013 ◽  
Author(s):  
Wenjing Zhao ◽  
Daniel C. Skaloud ◽  
Sascha Kutz ◽  
Hendrik Rothe ◽  
Cornelius F. Hahlweg
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
High Speed Imaging ◽  
Polarization Effects

Liquid Fuel Composition Effects on Forced, Non-Premixed Ignition

2016 ◽  
Author(s):  
Brandon Sforzo ◽  
Hoang Dao ◽  
Sheng Wei ◽  
Jerry Seitzman
Keyword(s):  
High Speed ◽  
Chemical Kinetic ◽  
Optical Measurements ◽  
Liquid Fuels ◽  
Kinetic Properties ◽  
Fuel Composition ◽  
Ignition Process ◽  
Oxidation Reactions ◽  
High Speed Imaging ◽  
Ignition Probability

The effects of jet fuel composition on ignition probability have been studied in a flowfield that is relevant to turbine engine combustors, but also fundamental and conducive to modeling. In the experiments, a spark kernel is ejected from a wall and propagates transversely into a crossflow. The kernel first encounters an air-only stream before transiting into a second, flammable (premixed) stream. The two streams have matched velocities, as verified by hot-wire measurements. The liquid fuels span a range of physical and chemical kinetic properties. To focus on their chemical differences, the fuels are prevaporized in a carrier air flow before being injected into the experimental facility. Ignition probabilities at atmospheric pressure and elevated crossflow temperature were determined from optical measurements of a large number of spark events, and high speed imaging was used to characterize the kernel evolution. Eight fuel blends were tested experimentally; all exhibited increasing ignition probability as equivalence ratio increased, at least up to 1.5. Statistically significant differences between fuels were measured that have some correlation with fuel properties. To elucidate these trends, the forced ignition process was also studied with a reduced order numerical model of an entraining kernel. The simulations suggest ignition is successful if sufficient heat release occurs before entrainment of colder crossflow fluid quenches the exothermic oxidation reactions. As the kernel is initialized in air, it remains lean during the initial entrainment of the fuel-air mixture; thus richer crossflows lead to quicker and higher exothermicity.

scholarly journals Investigation of the Effect of Electrode Surface Roughness on Spark Ignition

2018 ◽  
Author(s):  
Mohammadrasool Morovatiyan ◽  
Martia Shahsavan ◽  
Mengyan Shen ◽  
John Hunter Mack
Keyword(s):  
Surface Roughness ◽  
Electrode Surface ◽  
High Speed ◽  
Fuel Efficiency ◽  
Spark Ignition ◽  
Ignition Process ◽  
Flammability Limit ◽  
Lean Burn ◽  
Flame Kernel ◽  
Spark Plug

Lean-burn engines are important due to their ability to reduce emissions, increase fuel efficiency, and mitigate engine knock. In this study, the surface roughness of spark plug electrodes is investigated as a potential avenue to extend the lean flammability limit of natural gas. A nano-/micro-morphology modification is applied on surface of the spark plug electrode to increase its surface roughness. High-speed Z-type Schlieren visualization is used to investigate the effect of the electrode surface roughness on the spark ignition process in a premixed methane-air charge at different lean equivalence ratios. In order to observe the onset of ignition and flame kernel behavior, experiments were conducted in an optically accessible constant volume combustion chamber at ambient pressures and temperatures. The results indicate that the lean flammability limit of spark-ignited methane can be lowered by modulating the surface roughness of the spark plug electrode.

High‐speed imaging techniques for harpsichord plucking action.

2010 ◽  
Vol 127 (3) ◽  
pp. 1733-1733
Author(s):  
Marshall J. Brown ◽  
C.‐Y. Jack Perng ◽  
Thomas D. Rossing ◽  
Juliette W. Ioup
Keyword(s):  
High Speed ◽  
Imaging Techniques ◽  
High Speed Imaging

Electrically tunable lenses – eliminating mechanical axial movements during high-speed 3D live imaging

2021 ◽  
Vol 134 (16) ◽  
Author(s):  
Christoforos Efstathiou ◽  
Viji M. Draviam
Keyword(s):  
Cell Biology ◽  
High Speed ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Cost Effective ◽  
High Speed Imaging ◽  
Liquid Lenses ◽  
Live Cell Microscopy ◽  
Tunable Lenses ◽  
Cell Microscopy

ABSTRACT The successful investigation of photosensitive and dynamic biological events, such as those in a proliferating tissue or a dividing cell, requires non-intervening high-speed imaging techniques. Electrically tunable lenses (ETLs) are liquid lenses possessing shape-changing capabilities that enable rapid axial shifts of the focal plane, in turn achieving acquisition speeds within the millisecond regime. These human-eye-inspired liquid lenses can enable fast focusing and have been applied in a variety of cell biology studies. Here, we review the history, opportunities and challenges underpinning the use of cost-effective high-speed ETLs. Although other, more expensive solutions for three-dimensional imaging in the millisecond regime are available, ETLs continue to be a powerful, yet inexpensive, contender for live-cell microscopy.

Optical imaging techniques for hypersonic impulse facilities

2007 ◽  
Vol 111 (1115) ◽  
pp. 1-16 ◽  
Author(s):  
T. J. McIntyre ◽  
H. Kleine ◽  
A. F. P. Houwing
Keyword(s):  
Optical Imaging ◽  
High Speed ◽  
Imaging Techniques ◽  
Flow Visualisation ◽  
Complex Flows ◽  
High Speed Imaging ◽  
Time Resolved ◽  
Flow Parameters ◽  
Planar Laser ◽  
Recent Developments

Abstract The application of optical imaging techniques to hypersonic facilities is discussed and examples of experimental measurements are provided. Traditional Schlieren and shadowgraph techniques still remain as inexpensive and easy to use flow visualisation techniques. With the advent of faster cameras, these methods are becoming increasingly important for time-resolved high-speed imaging. Interferometry’s quantitative nature is regularly used to obtain density information about hypersonic flows. Recent developments have seen an extension of the types of flows that can be imaged and the measurement of other flow parameters such as ionisation level. Planar laser induced fluorescence has been used to visualise complex flows and to measure such quantities as temperature and velocity. Future directions for optical imaging are discussed.

Investigation of Auto-Ignition of a Pulsed Methane Jet in Vitiated Air Using High-Speed Imaging Techniques

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
W. Meier ◽  
I. Boxx ◽  
C. Arndt ◽  
M. Gamba ◽  
N. Clemens
Keyword(s):  
High Speed ◽  
Gas Flow ◽  
Imaging Techniques ◽  
Frame Rate ◽  
Experimental Arrangement ◽  
Single Shot ◽  
Exhaust Gas ◽  
High Speed Imaging ◽  
Auto Ignition ◽  
Flow Field Characteristics

An experimental arrangement for the investigation of auto-ignition of a pulsed CH4 jet in a coflow of hot exhaust gas from a laminar lean premixed H2/air flame at atmospheric pressure is presented. The ignition events were captured by high-speed imaging of the OH∗ chemiluminescence associated with the igniting flame kernels at a frame rate of 5 kHz. The flow-field characteristics were determined by high-speed particle image velocimetry and Schlieren images. Furthermore, high-speed imaging of laser-induced fluorescence of OH was applied to visualize the exhaust gas flow and the ignition events. Auto-ignition was observed to occur at the periphery of the CH4 jet with high reproducibility in different runs concerning time and location. In each measurement run, several hundred consecutive single shot images were recorded from which sample images are presented. The main goals of the study are the presentation of the experimental arrangement and the high-speed measuring systems and a characterization of the auto-ignition events occurring in this system.

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