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| 2. |
- Remie, Martin, et al.
(författare)
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Heat-transfer distribution for an impinging laminar flame jet to a flat plate
- 2008
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 51:11-12, s. 3144-3152
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Tidskriftsartikel (refereegranskat)abstract
- Impinging flame jets are widely used in applications where high heat-transfer rates are needed, for instance in the glass industry. During the heating process of glass products, internal thermal stresses develop in the material due to temperature gradients. In order to avoid excessive thermal gradients as well as overheating of the hot spots, it is important to know and control the temperature distribution inside a heated glass product. Therefore, it is advantageous to know the relation describing the convective heat–flux distribution at the heated side of a glass product. In a previous work, we presented a heat–flux relation applicable for the hot spot of the target [M.J. Remie, G. Sa¨rner, M.F.G. Cremers, A. Omrane, K.R.A.M. Schreel, M. Alde´n, L.P.H. de Goey, Extended heat-transfer relation for an impinging laminar flame jet to a flat plate, Int. J. Heat Mass Transfer, in press]. In this paper, we present an extension of this relation, which is applicable for larger radial distances from the hot spot.
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| 4. |
- Brackmann, Christian, et al.
(författare)
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Strategies for formaldehyde engines using a single-mode detection in flames and Nd : YAG/OPO laser system
- 2005
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Ingår i: Applied Spectroscopy. - 1943-3530. ; 59:6, s. 763-768
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents technical developments for the detection of formaldehyde (CH2O) using laser-induced fluorescence. The easily accessible third harmonic of the Nd:YAG laser at 355 nm was used for excitation of formaldehyde. In order to investigate potential background fluorescence, e.g., from large molecules such as polyaromatic hydrocarbons, special attention was paid to investigating the possibility of scanning the wavelength of a single-mode Nd:YAG laser under the gain profile, similar to 3 cm(-1), on and off resonance. Furthermore, a technique for simultaneous detection of formaldehyde and 011 using one laser system is presented. The single-mode Nd:YAG laser at 355 nm in combination with an optical parametric oscillator (OPO) laser tuned to 283 nm was used for simultaneous two-dimensional imaging of both species using one charge-coupled device (CCD) detector equipped with a dual filter image separator. The techniques are demonstrated with measurements in laboratory flames and the combined measurements are also demonstrated in an engine.
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| 5. |
- Husberg, Tobias, 1975, et al.
(författare)
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Piston temperature measurement by use of thermographic phosphors and thermocouples in a heavy-duty diesel engine run under partly premixed conditions
- 2005
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- Piston temperature experiments were conducted in a single-cylinder heavy-duty Diesel research engine, based on the Volvo Powertrain D12C engine both by use of optical temperature sensitive phosphor and of thermocouples mounted on the piston surface. In the former case, a thin coating of a suitable thermographic phosphor was applied to the areas on the piston surface to be investigated. The optical measurements of piston temperatures made involved use of an optical window and of an endoscope. The possibility of using optical fibres into guide light in and out of the engine was also investigated. Results of the optical and of the thermocouple measurements were compared and were also related to more global data with the aim of exploring the use of thermographic phosphors for piston- temperature measurements in Diesel engines. Thermographic phosphors thermometry was found to represent an alternative to the thermocouple method since it easily can be applied to various piston geometries. The method was seen to have a clear potential for production-type engine applications, particularly with use of fibre optics. Copyright © 2005 SAE International.
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| 6. |
- Li, Bo, et al.
(författare)
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Experimental and numerical study of a conical turbulent partially premixed flame
- 2009
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 32, s. 1811-1818
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Tidskriftsartikel (refereegranskat)abstract
- The structure and dynamics of a turbulent partially premixed methane/air flame in a conical burner were investigated using laser diagnostics and large-eddy simulations (LES). The flame structure inside the cone was charecterized in detail using LES based on a two-scalar flamelet model, with the mixture fraction for the mixing field and level-set G-function for the partially premixed flame front propagation. In addition, planar laser induced florescence (PLIF) of CH and chemiluminiscence imaging with high speed video were performed through a glass cone. CH and CH2O PLIF were also used to examine the flame structures above the cone. It is shown that in the entire flame the CH layer remains very thin, whereas the CH2O layer is rather thick. The flame is stabilized inside the cone a short distance above the nozzle. The stabilization of the flame can be simulated by the triple-flame model but not the flamelet-quenching model. The results show that flame stabilization in the cone is a result of premixed flame front propagation and flow reversal near the wall of the cone which is deemed to be dependent on the cone angle. Flamelet based LES is shown to capture the measured CH structures whereas the predicted CH2O structure is some-what thinner than the experiments.
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| 7. |
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| 8. |
- Li, Zhongshan, et al.
(författare)
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Mid-infrared polarization spectroscopy of polyatomic molecules: Detection of nascent CO2 and H2O in atmospheric pressure flames
- 2005
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 407:4-6, s. 243-248
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Tidskriftsartikel (refereegranskat)abstract
- We report the application of mid-infrared polarization spectroscopy (IRPS) for detection of nascent CO2 and H2O in atmospheric pressure flames. The recorded IRPS spectra demonstrated both the quantitative nature of the method and the suppression of strong infrared emission from flames. In spite of the high line-density of the hot polyatomic ro-vibrational spectrum, lines belonging to different CO2 and H2O hot bands were recognized in the chosen spectral region, which ensures the species-selective application of IRPS.
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| 9. |
- Li, Zhongshan, et al.
(författare)
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Mid-infrared PS and LIF detection of CH4 and C2H 6 in cold flows and flames at atmospheric pressure
- 2005
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 30:1, s. 1629-1636
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Tidskriftsartikel (refereegranskat)abstract
- Mid-infrared polarization spectroscopy (IRPS) and laser-induced fluorescence (IRLIF) have been applied for detection of methane and ethane in atmospheric pressure cold flows and flames. Lines belonging to the asymmetric C-H stretching vibration bands v3 and v7 for methane and ethane, respectively, were probed with a tunable infrared laser beam at about 3.4 μm, which was obtained from difference frequency generation in a LiNbO3 crystal pumped by a dye-laser beam and a Nd:YAG fundamental laser beam. The dependence of IRPS and IRLIF signal of CH4 on different buffer gases, including He, Ar, N2, and CO2 was investigated. Simultaneous measurements of IRPS and IRLIF signals allowed a direct comparison of the two techniques, and IRPS was found to be superior in detection sensitivity and background discrimination. IRPS excitation scans of a methane and ethane mixture diluted in Ar were also performed in a jet at ambient pressure and temperature. Lines in the spectrum belonging to methane and ethane were fully recognized and assigned. From the ethane lines in the IRPS excitation spectrum, a detection limit of 50 ppm was conservatively estimated, and this indicates that IRPS is a promising sensitive technique for hydrocarbon identification and detection. Finally, CH4 IRPS detection in a CH4/H2/air premixed flat flame was demonstrated, with spatially resolved IRPS CH4 measurements along different heights in the flame.
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