Laser-induced fluorescence with tunable excimer lasers as a possible method for instantaneous temperature field measurements at high pressures: checks with an atmospheric flame

Andresen, Peter L.; Bath, A.; Gröger, W.; Lülf, H. W.; Meijer, Gerard; Meulen, J. J. ter

doi:10.1364/ao.27.000365

Cited by 230 publications

(71 citation statements)

References 30 publications

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“…The growth of laser spectrometry has, in part, been the result of advances in laser technology, including the advent of high-powered, ultrashort-pulsed, narrow-bandwidth, tunable lasers that can produce wavelengths ranging from the infrared to the vacuum ultraviolet. 18), 19) This significant advance enables many automated analytical methods to be developed, including laser-induced fluorescence spectrometry (LIF), 20)῍23) laser-induced breakdown spectrometry, 24)῍27) tunable diode-laser ab-sorption spectrometry, 28)῏31) Raman spectrometry, 32)῏36) and mass spectrometry with resonance-enhanced multi-photon ionization (REMPI).…”

Section: )῍17)mentioning

confidence: 99%

Automated Analysis of Persistent Organic Pollutants in the Gas Phase by Laser Ionization Mass Spectrometry

Dobashi

Yamaguchi

Izawa

et al. 2010

J. Mass Spectrom. Soc. Jpn.

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Persistent organic pollutants (POPs) are toxic chemicals that adversely a#ect human health and the environment around the world. The detection and evaluation of small amounts of POPs require methods with both high precision and high chemical selectivity. Conventional methods involve a number of preparatory steps and time-consuming analysis and are not suitable for the abovementioned purposes. Hence, new automated analysis methods are required for on-line detection and rapid analysis of POPs. In this paper, mass spectrometry with resonance-enhanced multi-photon ionization (REMPI) is performed to obtain information about the automated analysis of POPs in the gas-phase with on-line detection. Dynamic trapping time-of-flight mass spectrometry (TOFMS) was performed with su$cient selectivity and sensitivity for rapid analysis of polychlorinated biphenyls (PCBs) in the gas phase. Compared to normal trapping, the use of dynamic trapping enabled ion signal intensity to be increased by a factor of greater than 10. The detection limit at 1 min was ῍1 ppbV, and the accuracy also correlated well with the results of conventional analysis. Based on these results, an automated monitoring system was developed for automated analysis of PCBs. It was confirmed that this monitoring system was capable of analyzing PCB concentration without being influenced by main gas components or various coexisting substances, even under conditions characterized by exhaust gas and the work environment atmosphere. PCB concentration in PCB waste plants, which is substantially lower than the 0.10 mg/m 3 N specified in statutory regulations, could be analyzed within 1 min. It was possible to make continuous long-term analysis for over 2,000 h (120,000 points).

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Section: )῍17)mentioning

confidence: 99%

Automated Analysis of Persistent Organic Pollutants in the Gas Phase by Laser Ionization Mass Spectrometry

Dobashi

Yamaguchi

Izawa

et al. 2010

J. Mass Spectrom. Soc. Jpn.

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“…CO 2 does not absorb at 248 nm and thus gives no contribution to the fluorescence [3]. Water fluorescence can, however, be induced via a two-photon transition at 124 nm (1/2 × 248 nm) [15]. This process is weak and a possible contribution from water will be negligible.…”

Section: Imaging Measurementsmentioning

confidence: 99%

Crank Angle Resolved HC-Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed

Andersson¹,

Juhlin²,

Ekenberg³

et al. 1996

SAE Technical Paper Series

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In order to separate the HC-emissions from two-stroke engines into short-circuit losses and emissions due to incomplete combustion, Laser Induced Fluorescence (LIF) measurements were performed on the exhaust gases just outside the exhaust ports of two engines of different designs.The difference between the two engines was the design of the transfer channels. One engine had "finger" transfer channels and one had "cup handle" transfer channels. Apart from that they were similar. The engine with "finger" transfer channels was earlier known to give more short-circuiting losses than the other engine, and that behavior was confirmed by these measurements.Generally, the results show that the emission of hydrocarbons has two peaks, one just after exhaust port opening and one late in the scavenging phase.The spectral information shows differences between the two peaks and it can be concluded that the latter peak is due to short-circuiting and the earlier due to incomplete combustion.The flow outside the exhaust port was measured with Laser Doppler Velocimetry (LDV). These measurements confirm the occurrence of two emission peaks.

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“…This procedure is therefore likely to produce much greater uncertainties if used within a scramjet combustion chamber. A Raman/LIPF (Predissociative LIF, see [48]) method was used by Cheng et al [49] to examine laminar hydrogen jet diffusion flames. In this study, the (3, 0) band was excited in the OH A−X transition, which is predissociative due to transfer into the repulsive a state.…”

Section: Oh Studiesmentioning

confidence: 99%

“…Once molecules are in the excited state, interactions with other molecules can result in deexcitation, quenching the fluorescence signal [40,41,48]. This process, known as collisional quenching, is highly dependent on pressure [41], as higher number densities increase the chance of an excited molecule interacting with a collision partner.…”

Section: Collisional Quenchingmentioning

confidence: 99%

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Experimental Investigation of a 3D Thermal Compression Scramjet Using Advanced Optical Techniques

Vanyai¹

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Scramjet engines are limited in performance due to engine starting problems at low hypersonic speeds. For an accelerating hypersonic vehicle, intake contraction ratios are typically fixed to the low speed starting requirements. This reduces engine performance at higher Mach numbers, where higher contraction ratios are required to efficiently combust flow within a practically-sized combustor.The use of a combustion process called "Thermal Compression" was suggested in the 1960s that could improve the performance of low intake contraction scramjet engines. In such an engine, the flow field is non-uniform within the combustor, with regions of locally high pressure and temperature even at low net intake contraction ratio. The flow properties in these regions are suitable for combustion of air-fuel mixtures, inducing autoignition. As heat is released, increased temperature and pressure are transmitted to the surrounding flow through pressure waves. Conditions in the surrounding flow become suitable for combustion, and this process continues until combustion completes throughout the entire flow field.This work presents results from experimental and numerical analysis of a three-dimensional, thermal compression scramjet engine at two high Mach number flight conditions. Experiments were conducted in the T4 Shock Tunnel at The University of Queensland. The tunnel test gas simulated flow that had been processed by an engine forebody at either 8.0• or 8.8• angle of attack, in an equivalent flight condition of Mach 10, 50 kPa dynamic pressure.An engine test model was developed to examine the effect of thermal compression on combustion-induced pressure rise at these inflow conditions. Non-uniform combustor flow was generated using a three-dimensional intake with a ramp angle that varied in the spanwise direction. This produced a low compression side and a high compression side throughout the scramjet engine. Fuel injection plenums were split such that different gases could be injected in either the low compression or high compression side. Combustion was induced by injecting hydrogen fuel, or suppressed by injecting helium.i Pressure measurements were taken along the streamwise length of the engine, in three spanwise locations. Optical techniques, including emission and laser-induced fluorescence (LIF) methods, were used to visualise the distribution of OH radicals throughout the combustor. These experimental results were then compared to fully-combusting, RANS CFD simulations.The influence of thermal compression was determined by comparing combustion-induced pressure rise in the fully-fuelled case to the sum of both cases where combustion was suppressed on each side of the engine. It was found that for the forebody angle of 8.8• case, thermal compression increased pressure rise by 14.4 ± 6.0 % and 6.7 ± 6.2 % for fuel-air equivalence ratios of φ = 0.8 and φ = 1.0 respectively. Emission from OH radicals, which is qualitatively indicative of combustion, also increased by 19 -54 % in the rear of the combustor. Numerica...

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Laser-induced fluorescence with tunable excimer lasers as a possible method for instantaneous temperature field measurements at high pressures: checks with an atmospheric flame

Cited by 230 publications

References 30 publications

Automated Analysis of Persistent Organic Pollutants in the Gas Phase by Laser Ionization Mass Spectrometry

Automated Analysis of Persistent Organic Pollutants in the Gas Phase by Laser Ionization Mass Spectrometry

Crank Angle Resolved HC-Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed

Experimental Investigation of a 3D Thermal Compression Scramjet Using Advanced Optical Techniques

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