Pyrene-LIF Thermometry of the Early Soot Formation Region in a Diesel Spray Flame

2005 ◽  
Author(s):  
Tetsuya Aizawa ◽  
Hidenori Kosaka
Keyword(s):  
Soot Formation ◽  
Diesel Spray ◽  
Formation Region ◽  
Spray Flame

Two-dimensional imaging of ignition and soot formation processes in a diesel flame

2005 ◽  
Vol 6 (1) ◽  
pp. 21-42 ◽  
Author(s):  
H Kosaka ◽  
T Aizawa ◽  
T Kamimoto
Keyword(s):  
Soot Formation ◽  
Diesel Spray ◽  
Oxidation Reactions ◽  
Soot Particles ◽  
Nozzle Orifice ◽  
Spray Flame ◽  
Soot Precursor ◽  
Planar Laser ◽  
Laser Induced Incandescence ◽  
Ambient Gas

The processes of ignition and formation of soot precursor and soot particles in a diesel spray flame achieved in a rapid compression machine (RCM) were imaged two-dimensionally using the laser sheet techniques. For the two-dimensional imaging of time and of location where ignition first occurs in a diesel spray, planar laser-induced fluorescence (PLIF) of formaldehyde was applied to a diesel spray in an RCM. Formaldehyde has been hypothesized to be one of the stable intermediate species marking the start of oxidation reactions in a transient spray under compression ignition conditions. In this study, the laser-induced fluorescence (LIF) images of the formaldehyde formed in a diesel fuel spray during the ignition process have been obtained by exciting formaldehyde with the third harmonic of a neodymium-doped yttrium aluminium garnet (Nd:YAG) laser. The LIF images of formaldehyde in a spray revealed that the time when the first fluorescence is detected is almost identical with the time when the total heat release due to low-temperature oxidation reactions equals the heat absorption by fuel vaporization in the spray. The formaldehyde level rose steadily until the high-temperature reaction phase of diesel spray ignition. At the start of this ‘hot-ignition’ phase, the formaldehyde concentration fell rapidly, thus signalling the end of the low-temperature ignition phase. Increases in the initial ambient gas temperatures advanced the hot-ignition starting time. The first hot ignition occurred in the periphery of spray head at initial ambient gas temperatures between 580 and 660 K. When the ambient gas temperature was increased to 790 K, the position of the first ignition moved to the central region of the spray head. For the investigation of soot formation processes in a diesel spray flame, simultaneous imaging of the soot precursor and soot particles in a transient spray flame in an RCM was conducted by PLIF and by planar laser-induced incandescence (PLII) techniques. The third harmonic (355 nm) and the fundamental (1064 nm) laser pulses from an Nd:YAG laser, between which a delay of 44 ns was imposed by 13.3 m of optical path difference, were used to excite LIF from the soot precursor and laser-induced incandescence (LII) from soot particles in the spray flame. The LIF and the LII were separately imaged by two image-intensified charge-coupled device cameras with identical detection wavelengths of 400 nm and bandwidths of 80 nm. The LIF from the soot precursor was mainly located in the central region of the spray flame between 40 and 55 mm (between 270 and 370 times the nozzle orifice diameter d°) from the nozzle orifice. The LII from soot particles was observed to surround the soot precursor LIF region and to extend downstream. The first appearance of the LIF from the soot precursor in the spray flame preceded the appearance of the LII from soot particles. The intensity of the LIF from the soot precursor reached its maximum immediately after rich premixed combustion. In contrast, the intensity of the LII from soot particles increased gradually and reached its maximum after the end of injection. Measured LIF spectra, of the soot precursor in the spray flame, were very broad with the peak between 430 and 460 nm.

Thermocouple temperature measurements in diesel spray flame for validation of in-flame soot formation dynamics

2016 ◽  
Vol 18 (5-6) ◽  
pp. 453-466 ◽  
Author(s):  
Tetsuya Aizawa ◽  
Tsuyoshi Harada ◽  
Katsufumi Kondo ◽  
Takayuki Adachi ◽  
Beini Zhou ◽  
...  
Keyword(s):  
Soot Formation ◽  
Temperature Measurements ◽  
Diesel Spray ◽  
Spray Flame ◽  
Formation Dynamics ◽  
Thermocouple Temperature

Vortex Development and Heat Release Enhancement in Diesel Spray Flame by Inversed-Delta Injection Rate Shaping Using TAIZAC Injector

2021 ◽  
Author(s):  
Tetsuya Aizawa ◽  
Tomoki Kinoshita ◽  
Yohei Tanaka ◽  
Tatsuki Takahashi ◽  
Yuusei Miyagawa ◽  
...  
Keyword(s):  
Heat Release ◽  
Injection Rate ◽  
Diesel Spray ◽  
Spray Flame ◽  
Rate Shaping
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