IGNITION AND STABILIZATION OF HOMOGENEOUS COMBUSTION IN HIGH-SPEED FLOW BY PULSE-PERIODIC LASER RADIATION

2020 ◽  
Author(s):  
V. N. Zudov ◽  
◽  
P. K. Tretyakov ◽  
A. V. Tupikin ◽  
◽  
...  
Keyword(s):  
Co2 Laser ◽  
High Speed ◽  
Radiation Spectrum ◽  
Combustion Process ◽  
Frame Rate ◽  
Optical Discharge ◽  
Speed Flow ◽  
Homogeneous Combustion ◽  
And Behavior ◽  
Spectrozonal Registration

The paper present the results of an experimental study of the effect of focused pulsed-periodic radiation from a CO2 laser on the initiation and development of a combustion process in subsonic and supersonic flows of homogeneous fuel-air mixtures (H2 + air and CH4 + air). The radiation from the CO2 laser propagated across the stream and was focused on the jet axis. To register the flow structure, a schlieren imaging setup with a slit and a flat knife was used. The image was recorded by a high-speed camera with exposure time of 1.5 s and frame rate of 1000 fps. At the same time, spectrozonal recording (at the wavelength of OH* and CH* radiation) and emission spectroscopy (in the wavelength range of 210-780 nm) was carried out. Stable ignition of methane and hydrogen-air mixture has been obtained at supersonic outflow into the flooded space. The results of the spectrozonal registration indicate the occurrence of combustion reactions in the wake behind the optical discharge region. The analysis of the radiation spectrum of optical discharge in a supersonic flow revealed the main types of radicals present in the plasma. Strong intensity was found in the H lines, which cannot help but affect the development of the initiation and behavior of the combustion process in the wake of the optical discharge.

Dynamic PIV Measurement of High-Speed Mist Flow

2004 ◽  
Author(s):  
Masaaki Ishikawa ◽  
Seong-Dae Hong ◽  
Koji Okamoto ◽  
Haruki Madarame
Keyword(s):  
High Speed ◽  
Dead Time ◽  
High Repetition Rate ◽  
Frame Rate ◽  
Particle Image Velocimetry System ◽  
High Speed Flow ◽  
Camera System ◽  
Speed Flow ◽  
Piv Measurement ◽  
Dynamic Piv

Recently PIV (Particle Image Velocimetry) system which consists of high-speed cameras with 1k × 1k pixels and 2 kHz in frame rate and high-repetition rate and high-power double-pulse lasers has been developed. Previous PIV system is difficult to visualize the sequential instantaneous images in high-speed flow because of low frame rate as 30Hz and was used to apply to periodic flow and steady flow. According to this latest PIV system, it is possible to acquire high-speed flow of 1 msec consecutively. This camera system is called “Dynamic PIV system” or “High-Speed PIV system”. Also in PIV it is possible to capture two-consecutive images for about a micro-second to use the frame straddling technique. But in latest high-speed camera it has limitation because dead time which is to flush the charged electron perfectly is longer and it has a several micro-seconds. This purpose of study is to develop the new Dynamic PIV system which is possible to capture the two-consecutive images for less than dead time. Furthermore it is applied to the high-speed mist jet flow with 50m/s in order to elucidate this system.

An Investigation of Flame Expansion Speed With a Strong Swirl Motion Using High-Speed Visualization

2003 ◽  
Vol 125 (2) ◽  
pp. 485-493
Author(s):  
S. H. Joo ◽  
K. M. Chun ◽  
Y. Shin ◽  
K. C. Lee
Keyword(s):  
High Speed ◽  
Combustion Process ◽  
Flow Characteristics ◽  
Video Camera ◽  
Frame Rate ◽  
Superposition Method ◽  
Linear Superposition ◽  
Compression Stroke ◽  
Engine Cylinder ◽  
Expansion Speed

In this study, a simple linear supposition method is proposed to separate the flame expansion speed and swirl motion of a flame propagating in an engine cylinder. Two series of images of flames propagating in the cylinder with/without swirl motion were taken by a high frame rate digital video camera. A small tube (4 mm ID) was installed inside the intake port to deliver the fuel/air mixture with strong swirl motion into the cylinder. An LDV was employed to measure the swirl motion during the compression stroke. Under the assumption that flame propagates spherically from the each point of the flame front, a diameter of small spherical flames can be calculated from the two consecutive images of the flame without swirl motion in the cylinder. Using the normalized swirl motion of the mixture during the compression stroke and the spherical flame diameters, the flame expansion speed and swirl ratio of combustion propagation in the engine cylinder can be obtained. This simple linear superposition method for separating the flame expansion speed and swirl motion can be utilized to understand the flow characteristics, such as swirl and turbulence, during the combustion process.

Flutter Limits and Behavior of a Flexible Thin Sheet in High-Speed Flow— II: Experimental Results and Predicted Behaviors for Low Mass Ratios

1999 ◽  
Vol 122 (1) ◽  
pp. 74-83 ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Tooru Sekiguchi ◽  
Kazuhiko Yokota ◽  
Yoshinobu Tsujimoto
Keyword(s):  
High Speed ◽  
Thin Sheet ◽  
Fluid Pressure ◽  
Mass Effect ◽  
Inertia Force ◽  
Speed Flow ◽  
Wide Range ◽  
Mass Ratios ◽  
Low Mass ◽  
And Behavior

Flutter phenomena of flexible thin sheets such as paper swept by wind are studied for a wide range of mass ratios by an analytical method developed by the authors. The analytical results explain well the tendencies found in the experimental data. Furthermore, the flutter behaviors for very low mass ratios are predicted to tend to deviate far from those for ordinarily stiff materials, which are attributed to the effects of both the fluid friction and the added mass effect by surrounding fluid in addition to the ordinary governing effects for higher mass ratios, i.e., elasticity, inertia force, and fluid pressure. [S0098-2202(00)01201-3]

Two-Phase Heat Transfer and Flow Regimes in Pin Fin-Enhanced Microgaps—Effect of Pin Spacing

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Pouya Asrar ◽  
S. Mostafa Ghiaasiaan ◽  
Yogendra K. Joshi
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Flow Boiling ◽  
Frame Rate ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Pin Fin ◽  
Speed Flow ◽  
Wide Range ◽  
Two Phase Heat Transfer

Abstract An experimental investigation of the flow boiling of dielectric refrigerant R245fa is conducted in microgaps with enhancement features. A silicon microgap of height 200 μm populated with pin fin arrays of diameter 150 μm with spacing 200 μm in both horizontal and vertical directions is examined. For five different test conditions and in a wide range of mass flux from 781 to 5210 kg/m2s, and inlet temperatures in the range of 13–18 °C, average single-phase and two-phase heat transfer coefficients, pressure drop, and exit vapor quality are reported. Three major flow patterns are observed in the pin finned area using high-speed flow visualization at frame rate of 2229 fps: foggy, bubbly, and slug flow. Based on the experimental data, a flow regime map is constructed.

Visualization of High Speed Flow in a Pipe with Cavity

1997 ◽  
Vol 17 (Supplement2) ◽  
pp. 113-116
Author(s):  
Kenji HOSOI ◽  
Masaaki KAWAHASHI ◽  
Hiroyuki HIRAHARA ◽  
Kouju SHIOZAKI ◽  
Kenichirou SATOH
Keyword(s):  
High Speed ◽  
High Speed Flow ◽  
Speed Flow

Pulsed discharge-induced high-speed flow near a dielectric ledge

2021 ◽  
Vol 62 (7) ◽  
Author(s):  
D. I. Tatarenkova ◽  
E. Yu. Koroteeva ◽  
T. A. Kuli-zade ◽  
E. A. Karnozova ◽  
I. A. Znamenskaya ◽  
...  
Keyword(s):  
High Speed ◽  
Pulsed Discharge ◽  
High Speed Flow ◽  
Speed Flow

scholarly journals On-CMOS Image Sensor Processing for Lane Detection

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3713
Author(s):  
Soyeon Lee ◽  
Bohyeok Jeong ◽  
Keunyeol Park ◽  
Minkyu Song ◽  
Soo Youn Kim
Keyword(s):  
Edge Detection ◽  
High Speed ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Image Resolution ◽  
Lane Detection ◽  
Frame Rate ◽  
Total Power ◽  
Detection Accuracy ◽  
Total Power Consumption

This paper presents a CMOS image sensor (CIS) with built-in lane detection computing circuits for automotive applications. We propose on-CIS processing with an edge detection mask used in the readout circuit of the conventional CIS structure for high-speed lane detection. Furthermore, the edge detection mask can detect the edges of slanting lanes to improve accuracy. A prototype of the proposed CIS was fabricated using a 110 nm CIS process. It has an image resolution of 160 (H) × 120 (V) and a frame rate of 113, and it occupies an area of 5900 μm × 5240 μm. A comparison of its lane detection accuracy with that of existing edge detection algorithms shows that it achieves an acceptable accuracy. Moreover, the total power consumption of the proposed CIS is 9.7 mW at pixel, analog, and digital supply voltages of 3.3, 3.3, and 1.5 V, respectively.

Sign in / Sign up

Export Citation Format

Share Document