Spectral IR Images of Direct-Injection Diesel Combustion by High-Pressure Fuel Injection

Clasen, E.; Campbell, Steven; Rhee, K. T.

doi:10.4271/950605

Cited by 14 publications

(6 citation statements)

References 5 publications

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“…Close to the start of injection, longer exposure times were tested in order to determine whether it is possible to detect any flame emission prior to the diffusion-combustion phase, during which the flame emission is totally dominated by the soot luminosity [17]. Although diesel ignition is widely considered to occur at the time indicated by the first signs of combustion-induced release of heat (a rise in pressure), it is well known that some weak emission of light takes place before this time [32][33][34][35]. This emission is likely to originate from chemiluminescent reactions of combustion radicals, which are produced during the break down of fuel.…”

Section: Experimental Results From Large Enginesmentioning

confidence: 99%

A system for quantitative imaging diagnostics and its application to pyrometric in-cylinder flame-temperature measurements in large diesel engines

Vattulainen

Nummela

Hernberg

et al. 2000

Meas. Sci. Technol.

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This paper describes the development and a demanding field application of a double charge-coupled device (CCD) camera system, which allows simultaneous imaging at two different wavelength bands through common front-end optics. The imaging system has been assembled using two 1280 × 1024-pixel, 12-bit digital cameras together with standard, commercially available optical components for image splitting and filtering. The pixel resolution and wavelength separation of the system can be changed according to the requirements of the given application and the basic optical set-up can be used together with a variety of different types of front-end optics. The construction and performance of the double-camera system are described, together with preliminary experimental results from applying the system to in-cylinder combustion diagnostics of heavy-duty size-class, direct-injection diesel engines. To provide optical access into the combustion chamber of series-production-type engines, endoscope-based optics were used together with the camera system. Images taken at the two separate wavelength bands were used to calculate pyrometric diesel flame temperatures based on the blackbody radiation of the soot contained in the flame. The measurement system has been applied to engines with cylinder bores ranging from 20 cm up to 64 cm, delivering 0.15-1.6 MW power per cylinder during the measurements. In this paper specific results from measurements with Wärtsilä 4L20 and 6L32 engines are reported. These engines have 20 and 32 cm cylinder bores, respectively. In addition to the two-colour flame-temperature measurements, spectrally resolved measurements were performed to investigate a cloud-like, self-luminous phenomenon that was observed above the piston top even prior to the injection of fuel into these engines. This phenomenon was associated with the evaporating and chemically reacting fuel that originates from the residues which have been carried onto the piston top from the previous cycles. For the in-cylinder measurements reported here, the production-type test engines were only slightly modified to accept the endoscopic optics. During the measurements the engines were operated with realistic diesel fuels and other operation parameters. To the best of our knowledge, there have been no previous corresponding measurements reported in the literature for diesel engines of this size.

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Section: Experimental Results From Large Enginesmentioning

confidence: 99%

A system for quantitative imaging diagnostics and its application to pyrometric in-cylinder flame-temperature measurements in large diesel engines

Vattulainen

Nummela

Hernberg

et al. 2000

Meas. Sci. Technol.

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“…The crux of the combustion diagnostics is separation and spectroscopic identification of the emitters, including H 2 O, CO 2 , hydrocarbons, radical and intermediate species, soot, chamber wall and windows. 41,42 In contrast, the crux of the high-speed chamber wall thermography is separation of targeted wall surface radiation from flame soot luminosity and emissions of combustion products, for which the coating on the window is crucial as shown in the present study.…”

Section: Introductionmentioning

confidence: 74%

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

Aizawa

Kinoshita

Akiyama

et al. 2021

International Journal of Engine Research

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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.

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“…This system allows the spatial intensity distribution of an image to be determined at four narrow wavelength bands. Detailed descriptions of this optical train are provided by Clasen et al [18] and Song et al [53].…”

Section: Four-band Spatial Imaging Systemmentioning

confidence: 99%

“…The bore6stroke of the engine is 140-121 mm, with a compression ratio of 13.5:1. Further details of this engine and injector are available in earlier work [16][17][18][19][20]. The images shown in Fig.…”

Section: Diesel Imagingmentioning

confidence: 99%

“…Natural emission has been observed in the same 3.4 mm infrared range prior to auto-ignition in compression-ignition (CI) engines [16][17][18][19][20] and prior to ignition in spark-ignition (SI) engines at framing rates near 2000 frames/s [21,22]. While this wavelength falls within the 3340-2700 cm 21 (3.0-3.7 mm) C-H stretching region group frequency range of alkynes, aromatics, and aldehydes comprising diesel or gasoline fuels [23,24], important radical species that are formed in excited states such as OH, NO 2 , and HCHO have strong bands in this region as well.…”

Section: Introductionmentioning

confidence: 99%

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Infrared spectral analysis of engine preflame emission

Jansons

Lin

Rhee

2008

International Journal of Engine Research

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An investigation has been conducted to examine the previously observed infrared emission occurring at the end of an engine's compression period. The infrared preflame spectrum is measured and quantitatively compared with a radiation emission model incorporating wall effects. The likelihood and degree of contributions to the observed emission by intermediate species under non-local thermodynamic equilibrium conditions are examined, and the viability of applying high-speed infrared imaging as a diagnostic technique for observing the distribution of fuel vapour is demonstrated. A Fastie—Ebert-type grating spectrophotometer was constructed to employ a 64×64 pixel platinum-silicide charge-coupled device imager. This instrument was integrated with a four-camera infrared spatial imaging system. The combined apparatus allows the simultaneous recording of the infrared spectra and four spatial images, each recorded through separate narrow-band filters. One filter is centred at 2.47 μm and another centred at 3.43 μm, covering strong H2O and hydrocarbon bands. Images are recorded at a framing rate of 1880 frames/s in 64-frame sequences from consecutive engine cycles and triggered at a chosen crank-angle position determined by a crankshaft-mounted encoder wheel. To interpret the measured spectrum, a line-by-line radiation model was created utilizing the high-resolution transmission (HITRAN) database of molecular parameters. This database includes spectral line data for radical and intermediate species including hydroxyl (OH) and formaldehyde (HCHO), and the alkyl compounds methane (CH4), ethylene (C2H4), and up to ethane (C2H6). The model predicts the spectra of an isothermal, homogeneous gas mixture consisting of fuel, residual gases H2O and CO2 in air at a given temperature, pressure and concentration, and considers the effect of interaction with an emitting combustion chamber wall. Preflame images and spectra were recorded from an optically accessible spark-ignition engine using four fuels representing minimal (CH4, C2H4), marginal (C2H6), and significant (propane, C3H8) cool-flame chemistry. Results show the measured preflame spectra of the four fuels to have similar large-scale features and magnitude, including the propane fuel known for chemiluminescence during low-temperature reactions. The preflame spectrum of the latter fuel mixture is notable for its lack of spectral features expected of HCHO or OH, suggesting that emission by intermediate species produced by low-temperature mechanisms is not readily evident in the infrared preflame spectrum. There is a high degree of correlation between the measured preflame spectra of CH4 and C2H4 mixtures and the spectrum modelled using parameter values reasonably representative of engine conditions. The prominent features of the observed infrared preflame spectra are explained by thermal emission of the species considered. Since reported absorption cross-sections of n-heptane, n-dodecane, and gasoline at 3.39 μm are greater than that of CH4, these fuels are expected to ...

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Spectral IR Images of Direct-Injection Diesel Combustion by High-Pressure Fuel Injection

Cited by 14 publications

References 5 publications

A system for quantitative imaging diagnostics and its application to pyrometric in-cylinder flame-temperature measurements in large diesel engines

A system for quantitative imaging diagnostics and its application to pyrometric in-cylinder flame-temperature measurements in large diesel engines

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

Infrared spectral analysis of engine preflame emission

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