This research is for the implementation of non-intrusive measurement techniques in the study of high temperature pipe flow. A low pressure, laboratory scale hybrid rocket motor simulator was built to achieve high temperatures with various gases. A quartz test section was designed, built, and implemented into the existing test setup to accommodate the laser beam of the existing Tunable Diode Laser Absorption Spectrometer (TDLAS) system which was designed to observe water vapor. A super-heated water vapor injector was designed to obtain the desired water vapor concentrations. Flow characteristics were simultaneously recorded using the existing TDLAS system and the DAQ system for temperatures for later comparison. A numerical study using a commercial CFD package was used to predict the flow characteristics at certain locations for experimental comparison. Based on this study, it is concluded that the TDLAS can be used to make real time temperature measurements of heated internal gas flows.

<p> A detailed experimental and theoretical study has been performed on several different photochemical systems. Lead-salt tunable diode lasers operating in the infrared region have been used as diagnostic tools to probe the molecules in these gaseous systems. Knowledge of these systems is expected to be useful in evaluating future schemes of laser isotope separation.</p> <p> In the course of this work a computerized digital technique has been developed that allows molecular parameters such as linestrength and linewidth to be obtained by measuring the infrared absorption on vibrational-rotational transitions of the molecule. Molecular concentrations can then be determined enabling one to gain valuable insight into the chemical processes occurring in the system.</p> <p> The digital technique was first tested on CO2 gas in a multi-pass White cell to verify the validity of the measurements. Subsequently, measurements were performed on mixtures of NH3/N2, NH3/Ar, HTO/H2O, and HTO/air. Those NH3 measurements that could be compared to previous measurements were found to be very accurate. For the HTO system, no previous measurements on linestrength and linewidth for the transitions examined have been performed.</p> <p> Described next is the application of the tunable diode laser diagnostic system to the investigation of infrared multiphoton dissociation of deuterated chloroform immersed in a chloroform bath. The sensitivity of the technique allowed for the measurement of the few parts per million of DCl formed by the photolysis of natural abundance CDCl3 in CHCl3.</p><p> In addition, the feasibility of transient detection with tunable diode lasers was examined. High fluence CO2 laser pulses were used to dissociate C3F6 or C2F3Cl and create CF2 radicals. Current-modulation of the tunable diode laser made it possible to monitor the transient CF2 radicals as they were formed, and as they subsequently decayed. The sensitivity of the transient detection technique was found to be limited by detector noise.</p> / Thesis / Master of Science (MSc)

No description available.

Lean, premixed combustion has enjoyed increased application due to the need to reduce pollutant emissions. Unfortunately, operating the flame at lean conditions increases susceptibility to thermoacoustic (TA) instability. Self-excited TA instabilities are a result of the coupling of the unsteady heat release rate of the flame with the acoustics of the combustion chamber. The result is large pressure oscillations that degrade performance and durability of combustion systems. Industry currently has no reliable tool to predict instabilities a priori. CFD simulations of full-scale, turbulent, reacting flows remain unrealizable. The work in this paper is part of a study that focuses on developing compact models of TA instabilities, i.e. acoustics and flame dynamics. Flame dynamics are defined as the response in heat release to acoustic perturbations. Models of flame dynamics can be coupled with models of combustor enclosure acoustics to predict TA instabilities. In addition, algorithms to actively control instabilities can be based on these compact models of flame dynamics and acoustics. The work outlined in this thesis aims at determining the flame dynamics model experimentally. Velocity perturbations are imparted on laminar and turbulent flames via a loudspeaker upstream of the flame. The response of the flame is observed through two measurements. Hydroxyl radical (OH*) chemiluminescence indicates the response in chemical reaction rate. Tunable Diode Laser Absorption Spectroscopy (TDLAS), centered over two water absorption features, allows a dynamic measurement of the product gas temperature. The response in product gas temperature directly relates to the enthalpy fluctuations that couple to the acoustics. Experimental frequency response functions of a laminar, flat-flame burner and a turbulent, swirl-stabilized combustor will be presented as well as empirical low-order models of flame dynamics. / Master of Science

This work discusses the development of a compact Tunable Diode Laser Absorption Spectrometer (TDLAS) for gas phase mixing ratio and temperature measurements of condensible vapors, in particular H2O and D2O, in supersonic flows. Through extensive pressure trace measurements and mass balances on the incoming species, the expected mixing ratio and temperature profiles of the condensible species along the supersonic nozzle have been characterized. Using a Tunable Diode Infrared laser operating in the 8 microns region, the possibility of nonintrusively measuring the gas phase mixing ratio and the temperature (even simultaneously) in a supersonic nozzle is demonstrated. The acquired spectroscopic data and the pressure trace measurements are compared and the results suggest the possibility to improve the instrument set-up and to improve the quality of the measurements. Also, the interpretation of our initial experimental results and the comparison with the pressure traces measurements suggest reasons to further investigate the condensation behavior of D2O and H2O.

Résumé : Ce travail avait pour but de contribuer à la détermination précise des paramètres de raies du disulfure de carbone en vue d'applications atmosphériques. Il s'agissait de déterminer théoriquement et expérimentalement les coefficients d'élargissement collisionnel de raies de la bande gamma 3 du disulfure de carbone perturbé par l'air atmosphérique ainsi que leur dépendance en température. Pour cela, nous avons déterminé les coefficients d'élargissement collisionnel du disulfure de carbone perturbé par l'azote, l'oxygène et enfin par l'argon, principaux composants de l'air atmosphérique, aussi bien que leur dépendance en température. En outre, nous avons déterminé théoriquement et expérimentalement les coefficients d'auto élargissement collisionnel de raies de la bande gamma 3 - gamma 1 du disulfure de carbone, à température ambiante. La dépendance vibrationnelle des largeurs collisionnelles étant négligeable, les résultats sont valables quel que soit le niveau supérieur de la transition. Enfin, nous avons déterminé les intensités absolues de quelques raies de la bande gamma 3 - gamma 1 du disulfure de carbone qui nous ont permis de mettre en exergue une des applications atmosphériques des paramètres de raie mesurés en laboratoire. Pour la partie expérimentale, un spectromètre diode-laser haute résolution (5x10-4cm-1) a été utilisé pour enregistrer les différents spectres. De ces derniers, nous avons déterminé les différents paramètres de raie d'absorption en ajustant aux profils expérimentaux des modèles de profils théoriques. Du point de vue théorique, les différents coefficients d'élargissement collisionnel ont été calculés sur base du formalisme semi-classique d'Anderson-Tsao-Curnutte amélioré par J. Bonamy et D. Robert, moyennant quelques modifications pour accorder les valeurs à celles mesurées en laboratoire. Ceci a permis de valider les différents potentiels d'interaction pour les différents systèmes moléculaires considérés. Abstract The purpose of this thesis was to contribute to the accurate determination of line parameters of carbon disulfide for atmospheric applications. We have determined experimentally as well as theoretically the collisional broadening coefficients of lines in the gamma 3 band of carbon disulfide perturbed by the atmospheric air and their temperature dependence. To this end, we determined collisional broadening coefficients, as well as their temperature dependence, of carbon disulfide diluted in nitrogen, oxygen and argon; the main components of the atmospheric air. In addition, we determined the self broadening coefficients of lines in the gamma 3 - gamma 1 band of carbon disulfide at room temperature. As the vibrational dependence of collisional widths is negligible, our results are valid whatever the higher level of transition. Finally, we determined the absolute intensities of a few lines in the gamma 3 - gamma 1 band of carbon disulfide, which have enabled us to highlight one of the atmospheric applications of line parameters measured in the laboratory. For the experimental part, a high resolution diode-laser spectrometer (5x10-4cm-1) was used to record the different spectra. Of these, we determined the parameters of absorption line by adjusting theoretical lineshape models to experimental profiles. From a theoretical point of view, different collisional broadening coefficients were calculated on the basis of semi classical formalism of Anderson-Tsao-Curnutte improved by J. Bonamy and D. Robert, with some modifications to make the calculated values more consistent with those measured. This enabled us to validate the different potentials of interactions for the different molecular systems considered.

The performance of a home-built tunable diode laser (TDL) spectrometer has been optimized regarding multi-line detection of carbon dioxide in natural gases. In the regime of the (30<SUP>0</SUP>1)<SUB>III</SUB> ← (000) band of <SUP>12</SUP>CO<SUB>2</SUB> around 1.6 μm, the dominating isotope species <SUP>12</SUP>CO<SUB>2</SUB>, <SUP>13</SUP>CO<SUB>2</SUB>, and <SUP>12</SUP>C<SUP>18</SUP>O<SUP>16</SUP>O were detected simultaneously. In contrast to most established techniques, selective measurements are performed without any sample preparation. This is possible since the CO<SUB>2</SUB> detection is free of interference from water, ubiquitous in natural gases. Detection limits in the range of a few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. Linear calibration plots cover a dynamic range of four orders of magnitude, allowing for quantitative CO<SUB>2</SUB> detection in various samples, like soil and breath gas. High isotopic resolution enables the excellent selectivity, sensitivity, and stability of the chosen analytical concept. The obtained isotopic resolution of typically ± 1.0 ‰ and ± 1.5 ‰ (for 3 vol. % and 0.7 vol. % of CO<SUB>2</SUB>, respectively) offers a promising analytical tool for isotope-ratio determination of carbon dioxide in soil gas. Preliminary experiments on soil respiration for the first time combine the on-line quantification of the overall carbon dioxide content with an optode sensor and isotopic determination (TDL system) of natural gas species.

This thesis describes the development of a sensing technique for temperature nonuniformity along the line of sight through combustion exhaust, geared for gas turbine applications. Tunable diode laser absorption spectroscopy is used to measure three absorption lines and compute a variable to characterize the level of temperature nonuniformity along the laser path. Nonuniformity information is obtained from one line of sight sensor because the absorption has a nonlinear dependence on temperature. This dependence is analyzed to determine the behaviour, shape, and response of absorption lines measured through mediums with nonuniform temperature profiles. Based on this analysis a new line selection process for nonuniformity sensing is developed. A sensor for temperature nonuniformity is proposed and demonstrated through computer simulations and experiments in the exhaust of a laboratory-scale combustor. The nonuniformity variable, U, is shown to monotonically track the level of temperature nonuniformity along the laser path. The capabilities of this sensing technique are determined based on a comprehensive analysis of errors and their effect on sensor performance. Methods to mitigate these errors are described, and the overall sensor capability is determined based on the characteristics of state of the art diode laser and absorption sensor technology. Such a sensor is capable of measuring minimum temperature deviations of 17% or more, which is well within the needed capabilities for industrial applications. Furthermore, the results and knowledge presented in this thesis apply to other absorption based sensing techniques.

No description available.

The nature of work conducted during the course of study towards a MSc degree focused on tunable diode laser absorption spectroscopy (TDLAS). This field involves the in-situ detection of gas constituents from low concentration samples. Specifically, I will focus on TDLAS systems utilizing practical optics, readymade electronics, and commercially available near infrared vertical cavity surface emitting lasers (VCSEL). In attempting to lower the minimum detectable concentrations of constituent gases, quantifying contributory noise sources is vital. Consequently, I seek to characterize principle noise sources of a prototypical TDLAS system in order to gain understanding of the limits that inhibit detection of trace gas concentrations. The noise sources which were focused on can be categorized as follows: source laser noise, optical noise, and detection noise. Through this work it was my goal to provide the means of achieving superior sensitivities.