Set-off length reduction by backward flow of hot burned gas surrounding high-pressure diesel spray flame from multi-hole nozzle

2016 ◽  
Vol 18 (3) ◽  
pp. 173-194 ◽  
Author(s):  
Takayuki Fuyuto ◽  
Yoshiaki Hattori ◽  
Hayato Yamashita ◽  
Naoki Toda ◽  
Makoto Mashida
Keyword(s):  
Combustion Chamber ◽  
Particle Tracking ◽  
Nozzle Exit ◽  
Particle Tracking Velocimetry ◽  
Diesel Spray ◽  
Optical Engine ◽  
Momentum Theory ◽  
Spray Flame ◽  
Lift Off ◽  
Length Reduction

The backward flow of the hot burned gas surrounding a diesel flame was found to be one of the factors reducing the set-off length (also called the lift-off length), that is, the distance from a nozzle exit into which a diffusion flame cannot intrude. In the combustion chamber of an actual diesel engine, the entrainment of the surrounding gas into a spray jet injected from a multi-hole nozzle is restricted by the combustion chamber walls and the adjacent spray jets, thus inducing the backward flow of the surrounding gas toward the nozzle exit. The emergence of this backward flow was measured by particle tracking velocimetry in the non-combusting condition. A new momentum theory for calculating the backward flow velocity was established by extending Wakuri’s momentum theory. Shadowgraph imaging in an optical engine successfully visualized the backward flow of the hot burned gas. The hot burned gas is re-entrained into the spray jet in the region of the set-off position and shortens the set-off length in comparison to that of a single free-spray flame which does not induce the backward flow.

Nanostructure characterization of soot particles from biodiesel and diesel spray flame in a constant volume combustion chamber

Fuel ◽  
2019 ◽  
Vol 235 ◽  
pp. 130-149 ◽  
Author(s):  
Felix Sebastian Hirner ◽  
Joonsik Hwang ◽  
Choongsik Bae ◽  
Chetankumar Patel ◽  
Tarun Gupta ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Constant Volume ◽  
Diesel Spray ◽  
Soot Particles ◽  
Spray Flame ◽  
Constant Volume Combustion ◽  
Constant Volume Combustion Chamber

scholarly journals Effects of inversed-delta injection rate shaping on diesel spray flame liquid length, lift-off length and soot onset

Fuel ◽  
2019 ◽  
Vol 258 ◽  
pp. 116170 ◽  
Author(s):  
Mohd Fareez Edzuan bin Abdullah ◽  
Akiyama Shinobu ◽  
Kinoshita Tomoki ◽  
Tetsuya Aizawa
Keyword(s):  
Injection Rate ◽  
Diesel Spray ◽  
Spray Flame ◽  
Rate Shaping ◽  
Lift Off

Infrared high-speed thermography of combustion chamber wall impinged by diesel spray flame

2021 ◽  
pp. 146808742110080
Author(s):  
Tetsuya Aizawa ◽  
Tomoki Kinoshita ◽  
Shinobu Akiyama ◽  
Kouya Shinohara ◽  
Yuusei Miyagawa
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Radiation ◽  
Combustion Chamber ◽  
High Speed ◽  
Chamber Wall ◽  
Maximum Temperature ◽  
Diesel Spray ◽  
Quartz Window ◽  
Spray Flame

As a demonstration of a new method to examine the extremely unsteady and spatially varying wall heat transfer phenomena on diesel engine combustion chamber wall, high-speed imaging of infrared thermal radiation from the wall surface impinged by a diesel spray flame was attempted using a high-speed infrared camera. A 35 mm-diameter chromium-coated quartz window surface was impinged by a diesel spray flame with an impinging distance of 27 mm from the nozzle orifice in a constant volume combustion chamber. The infrared thermal radiation from the back surface of the 0.6 µm thick chromium layer was successfully visualized at 10 kHz frame rate and 128 × 128 pixel resolution through the quartz window. The infrared radiation exhibited coherent and streaky structure with radial stripes extending and waving from the stagnation point. The width of the radial stripes, spatial amplitude and the period of the waving movement were comparable to the ones for turbulent heat transfer on the engine cylinder wall previously measured with a heat flux sensor, suggesting that they are resulting from the turbulent structure in the wall-impinging diesel flame. The radiation intensity was calibrated to temperature and converted to heat flux via 3-D numerical analysis of transient thermal conduction in the quartz window. The peak-to-peak variation amplitudes of temperature and heat flux among the radial stripes during the diesel spray flame impingement were about 20 K and 2.3 MW/m2, corresponding to 13% of 150 K maximum temperature swing amplitude and 18 MW/m2 maximum heat flux, respectively.

scholarly journals Quantifying the Response of Grass Carp Larvae to Acoustic Stimuli Using Particle-Tracking Velocimetry

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 603
Author(s):  
Hojung You ◽  
Rafael O. Tinoco
Keyword(s):  
Particle Tracking ◽  
Grass Carp ◽  
Particle Tracking Velocimetry ◽  
Quantitative Imaging ◽  
Functional Relation ◽  
Acoustic Signals ◽  
Ecological Impacts ◽  
Ctenopharyngodon Idella ◽  
Response Ratio ◽  
Larval Behavior

Acoustic deterrents are recognized as a promising method to prevent the spread of invasive grass carp, Ctenopharyngodon idella (Valenciennes, 1844) and the negative ecological impacts caused by them. As the efficacy of sound barriers depends on the hearing capabilities of carp, it is important to identify whether carps can recognize acoustic signals and alter their swimming behavior. Our study focuses on quantifying the response of grass carp larvae when exposed to out-of-water acoustic signals within the range of 100–1000 Hz, by capturing their movement using particle-tracking velocimetry (PTV), a quantitative imaging tool often used for hydrodynamic studies. The number of responsive larvae is counted to compute response ratio at each frequency, to quantify the influence of sound on larval behavior. While the highest response occurred at 700 Hz, we did not observe any clear functional relation between frequency of sound and response ratio. Overall, 20–30% of larvae were consistently reacting to sound stimuli regardless of the frequency. In this study, we emphasize that larval behaviors when exposed to acoustic signals vary by individual, and thus a sufficient number of larvae should be surveyed at the same time under identical conditions, to better quantify their sensitivity to sound rather than repeating the experiment with individual specimens. Since bulk quantification, such as mean or quantile velocities of multiple specimens, can misrepresent larval behavior, our study finds that including the response ratio can more effectively reflect the larval response.

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