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

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

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2010-22693 ◽

2010 ◽

Author(s):

Wolfgang Meier ◽

Isaac Boxx ◽

Christoph Arndt ◽

Mirko Gamba ◽

Noel 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 co-flow 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 PIV and Schlieren images. Further, 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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High-Speed Imaging of Gas Flow by Parallel Phase-Shifting Digital Holography

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 2, Fora ◽

10.1115/ajk2011-31012 ◽

2011 ◽

Cited By ~ 8

Author(s):

Takashi Kakue ◽

Tatsuki Tahara ◽

Yuki Shimozato ◽

Kenichi Ito ◽

Yasuhiro Awatsuji ◽

...

Keyword(s):

High Speed ◽

Digital Holography ◽

Gas Flow ◽

Image Sensor ◽

Phase Shifting ◽

Frame Rate ◽

Quarter Wave Plate ◽

Single Shot ◽

High Speed Imaging ◽

Phase Shifting Interferometry

We succeeded in high-speed imaging of gas flow by means of parallel phase-shifting digital holography. This technique is capable of capturing three-dimensional (3-D) information of object and carrying out phase-shifting interferometry with a single-shot exposure because the interference fringe images in which the information of multiple phase-shifted holograms is spatially multiplexed are simultaneously recorded. We constructed a high-speed phase-shifting digital holography system by employing a quarter-wave plate and a high-speed camera. The image sensor of the camera has an anisotropic polarization-detecting function pixel by pixel. Each pixel of the polarization-detecting function corresponds to each pixel of the image sensor. The phase retardation of the reference wave is determined by the direction of the polarization axis of the each pixel. A compressed gas flow sprayed from a nozzle was set as an object. We attained the reconstructed images of phase variation caused by the gas flow. We also succeeded in phase imaging at the rate of 180,000 frames per second when the number of pixels of the captured image was 128 × 128. Additionally, we also obtained temporal subtraction images of the reconstructed images. The achieved frame rate was the fastest among not only phase-shifting digital holography but also digital holography and phase-shifting interferometry which have been ever reported, for our knowledge. It is expected that parallel phase-shifting digital holography and the constructed system can contribute to 3-D moving picture measurement of dynamically moving objects such as particle flows, shock waves, mechanical vibration, and so on.

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High Speed Imaging Techniques For Pulse Nuclear Radiation Source

10.1117/12.969233 ◽

1989 ◽

Author(s):

Wang Kuilu ◽

Lu Ming ◽

Liu Cunfu ◽

Kang Dechun

Keyword(s):

Radiation Source ◽

High Speed ◽

Imaging Techniques ◽

Nuclear Radiation ◽

High Speed Imaging

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A portable smartphone-based laryngoscope system for high-speed vocal cord imaging of patients with throat disorders (Preprint)

10.2196/preprints.25816 ◽

2020 ◽

Author(s):

Jun Ki Kim ◽

Youngkyu Kim ◽

Jungmin Oh ◽

Seung-Ho Choi ◽

Ahra Jung ◽

...

Keyword(s):

Image Processing ◽

Vocal Cord ◽

High Speed ◽

High Performance ◽

Vocal Folds ◽

Frame Rate ◽

Endoscopic Imaging ◽

High Speed Imaging ◽

Underdeveloped Countries ◽

Longitudinal Edge

BACKGROUND Recently, high-speed digital imaging (HSDI), especially HSD endoscopic imaging is being routinely used for the diagnosis of vocal fold disorders. However, high-speed digital endoscopic imaging devices are usually large and costly, which limits access by patients in underdeveloped countries and in regions with inadequate medical infrastructure. Modern smartphones have sufficient functionality to process the complex calculations that are required for processing high-resolution images and videos with a high frame rate. Recently, several attempts have been made to integrate medical endoscopes with smartphones to make them more accessible to underdeveloped countries. OBJECTIVE To develop a smartphone adaptor for endoscopes to reduce the cost of devices, and to demonstrate the possibility of high-speed vocal cord imaging using the high-speed imaging functions of a high-performance smartphone camera. METHODS A customized smartphone adaptor was designed for clinical endoscopy using selective laser melting (SLM)-based 3D printing. Existing laryngoscope was attached to the smartphone adaptor to acquire high-speed vocal cord endoscopic images. Only existing basic functions of the smartphone camera were used for HSDI of the vocal folds. For image processing, segmented glottal areas were calculated from whole HSDI frames, and characteristics such as volume, shape and longitudinal edge length were analyzed. RESULTS High-speed digital smartphone imaging with the smartphone-endoscope adaptor could achieve 940 frames per second, and was used to image the vocal folds of five volunteers. The image processing and analytics demonstrated successful calculation of relevant diagnostic variables from the acquired images. CONCLUSIONS A smartphone-based HSDI endoscope system can function as a point-of-care clinical diagnostic device. Furthermore, this system is suitable for use as an accessible diagnostic method in underdeveloped areas with inadequate medical service infrastructure.

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Fast Objective Coupled Planar Illumination Microscopy

10.1101/501890 ◽

2018 ◽

Author(s):

Cody Greer ◽

Timothy E. Holy

Keyword(s):

Fluorescence Microscopy ◽

High Speed ◽

Imaging Techniques ◽

Light Sheet ◽

Frame Rate ◽

Three Dimensions ◽

Two Photon Microscopy ◽

Image Sharing ◽

Scanning Rate ◽

Fast Light

Among optical imaging techniques light sheet fluorescence microscopy stands out as one of the most attractive for capturing high-speed biological dynamics unfolding in three dimensions. The technique is potentially millions of times faster than point-scanning techniques such as two-photon microscopy. However current-generation light sheet microscopes are limited by volume scanning rate and/or camera frame rate. We present speed-optimized Objective Coupled Planar Illumination (OCPI) microscopy, a fast light sheet technique that avoids compromising image quality or photon efficiency. We increase volume scanning rate to 40 Hz for volumes up to 700 µm thick and introduce Multi-Camera Image Sharing (MCIS), a technique to scale imaging rate by parallelizing acquisition across cameras. Finally, we demonstrate fast calcium imaging of the larval zebrafish brain and find a heartbeat-induced artifact that can be removed by filtering when the imaging rate exceeds 15 Hz. These advances extend the reach of fluorescence microscopy for monitoring fast processes in large volumes.

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Nucleate Boiling From Micro-Machined Surfaces

Heat Transfer: Volume 2 ◽

10.1115/ht2003-47414 ◽

2003 ◽

Author(s):

Adrian M. Holland ◽

Colin P. Garner

Keyword(s):

Heat Transfer ◽

High Speed ◽

Imaging System ◽

Laser System ◽

Ccd Camera ◽

Nucleate Boiling ◽

Heat Fluxes ◽

Frame Rate ◽

High Speed Imaging ◽

Machined Surfaces

This paper discusses the production and use of laser-machined surfaces that provide enhanced nucleate boiling and heat transfer characteristics. The surface features of heated plates are known to have a significant effect on nucleate boiling heat transfer and bubble growth dynamics. Nucleate boiling starts from discrete bubbles that form on surface imperfections, such as cavities or scratches. The gas or vapours trapped in these imperfections serve as nuclei for the bubbles. After inception, the bubbles grow to a certain size and depart from the surface. In this work, special heated surfaces were manufactured by laser machining cavities into polished aluminium plates. This was accomplished with a Nd:YAG laser system, which allowed drilling of cavities of a known diameter. The size range of cavities was 20 to 250 micrometers. The resulting nucleate pool boiling was analysed using a novel high-speed imaging system comprising an infrared laser and high resolution CCD camera. This system was operated up to a 2 kHz frame rate and digital image processing allowed bubbles to be analysed statistically in terms of departure diameter, departure frequency, growth rate, shape and velocity. Data was obtained for heat fluxes up to 60 kW.m−2. Bubble measurements were obtained working with water at atmospheric pressure. The surface cavity diameters were selected to control the temperature at which vapour bubbles started to grow on the surface. The selected size and spacing of the cavities was also explored to provide optimal heat transfer.

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Light-In-Flight Imaging by a Silicon Image Sensor: Toward the Theoretical Highest Frame Rate

Sensors ◽

10.3390/s19102247 ◽

2019 ◽

Vol 19 (10) ◽

pp. 2247 ◽

Cited By ~ 3

Author(s):

Takeharu Etoh ◽

Tomoo Okinaka ◽

Yasuhide Takano ◽

Kohsei Takehara ◽

Hitoshi Nakano ◽

...

Keyword(s):

Temporal Resolution ◽

High Speed ◽

Streak Camera ◽

Image Sensor ◽

Pulse Neutron ◽

Frame Rate ◽

Neutron Tomography ◽

Single Shot ◽

Resolution Limit ◽

Lifetime Measurements

Light in flight was captured by a single shot of a newly developed backside-illuminated multi-collection-gate image sensor at a frame interval of 10 ns without high-speed gating devices such as a streak camera or post data processes. This paper reports the achievement and further evolution of the image sensor toward the theoretical temporal resolution limit of 11.1 ps derived by the authors. The theoretical analysis revealed the conditions to minimize the temporal resolution. Simulations show that the image sensor designed following the specified conditions and fabricated by existing technology will achieve a frame interval of 50 ps. The sensor, 200 times faster than our latest sensor will innovate advanced analytical apparatuses using time-of-flight or lifetime measurements, such as imaging TOF-MS, FLIM, pulse neutron tomography, PET, LIDAR, and more, beyond these known applications.

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