Letteratura scientifica selezionata sul tema "Phase Doppler Particle Analysis (PDPA)"
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Articoli di riviste sul tema "Phase Doppler Particle Analysis (PDPA)"
1
Lee, Seong W., Hu J. Cui e Yan H. Huang. "Particle Characteristics and Analysis Using the Laser-Based Phase Doppler Particle Analyzer (PDPA) and Statistical Method". Particulate Science and Technology 27, n. 3 (26 maggio 2009): 263–70. http://dx.doi.org/10.1080/02726350902922002.
Testo completo
2
Lee, Seong W., Hu J. Cui e Yan H. Huang. "Particle Characteristics and Analysis Using a Laser-Based Phase Doppler Particle Analyzer (PDPA) and Statistical Method". Particulate Science and Technology 27, n. 6 (20 novembre 2009): 553–61. http://dx.doi.org/10.1080/02726350903328845.
Testo completo
3
Tolpadi, A. K., D. L. Burrus e R. J. Lawson. "Numerical Computation and Validation of Two-Phase Flow Downstream of a Gas Turbine Combustor Dome Swirl Cup". Journal of Engineering for Gas Turbines and Power 117, n. 4 (1 ottobre 1995): 704–12. http://dx.doi.org/10.1115/1.2815456.
Testo completoAbstract (sommario):
The two-phase axisymmetric flow field downstream of the swirl cup of an advanced gas turbine combustor is studied numerically and validated against experimental Phase-Doppler Particle Analyzer (PDPA) data. The swirl cup analyzed is that of a single annular GE/SNECMA CFM56 turbofan engine that is comprised of a pair of coaxial counterswirling air streams together with a fuel atomizer. The atomized fuel mixes with the swirling air stream, resulting in the establishment of a complex two-phase flow field within the swirl chamber. The analysis procedure involves the solution of the gas phase equations in an Eulerian frame of reference using the code CONCERT. CONCERT has been developed and used extensively in the past and represents a fully elliptic body-fitted computational fluid dynamics code to predict flow fields in practical full-scale combustors. The flow in this study is assumed to be nonreacting and isothermal. The liquid phase is simulated by using a droplet spray model and by treating the motion of the fuel droplets in a Lagrangian frame of reference. Extensive PDPA data for the CFM56 engine swirl cup have been obtained at atmospheric pressure by using water as the fuel (Wang et al., 1992a). The PDPA system makes pointwise measurements that are fundamentally Eulerian. Measurements have been made of the continuous gas phase velocity together with discrete phase attributes such as droplet size, droplet number count, and droplet velocity distribution at various axial stations downstream of the injector. Numerical calculations were performed under the exact inlet and boundary conditions as the experimental measurements. The computed gas phase velocity field showed good agreement with the test data. The agreement was found to be best at the stations close to the primary venturi of the swirler and to be reasonable at later stations. The unique contribution of this work is the formulation of a numerical PDPA scheme for comparing droplet data. The numerical PDPA scheme essentially converts the Lagrangian droplet phase data to the format of the experimental PDPA. Several sampling volumes (bins) were selected within the computational domain. The trajectories of various droplets passing through these volumes were monitored and appropriately integrated to obtain the distribution of the droplet characteristics in space. The calculated droplet count and mean droplet velocity distributions were compared with the measurements and showed very good agreement in the case of larger size droplets and fair agreement for smaller size droplets.
4
Privitera, Salvatore, Emanuele Cerruto, Giuseppe Manetto, Sebastian Lupica, David Nuyttens, Donald Dekeyser, Ingrid Zwertvaegher, Marconi Ribeiro Furtado Júnior e Beatriz Costalonga Vargas. "Comparison between Liquid Immersion, Laser Diffraction, PDPA, and Shadowgraphy in Assessing Droplet Size from Agricultural Nozzles". Agriculture 14, n. 7 (19 luglio 2024): 1191. http://dx.doi.org/10.3390/agriculture14071191.
Testo completoAbstract (sommario):
Spray droplet diameters play a key role in the field of liquid plant protection product (PPP) application technology. However, the availability of various measurement techniques, each with its unique operating principles for evaluating droplet size spectra, can lead to different interpretations of spray characteristics. Therefore, in this study, four measurement techniques—Liquid Immersion (LI), Laser Diffraction (LD), Phase Doppler Particle Analysis (PDPA), and Shadowgraphy (SG)—were utilized to evaluate the droplet size distribution of agricultural spray nozzles. Additionally, PDPA and SG were used to assess the average velocity of spray droplets. Experiments were conducted in three different laboratories with the main aim of comparing results obtained with various types of equipment utilized under ordinary practical conditions. Spraying tests were carried out using three flat fan nozzles and an air-induction flat fan nozzle. As a general trend, the lowest values for droplet diameters were measured using the Laser Diffraction technique, followed by Shadowgraphy. The PDPA technique provided the highest values for mean diameters (D10, D20, and D30) and the numeric median diameter (Dn0.5), whereas the Liquid Immersion method yielded the highest values for the Sauter mean diameter (D32) and volumetric diameters (Dv0.1, Dv0.5, and Dv0.9). Importantly, all measurement techniques were able to discriminate the four nozzles based on their Dv0.5 diameter. Average droplet velocities showed a similar pattern across the four nozzles with the PDPA and the SG measurement techniques. The differences in diameter values observed with the four measurement techniques underline the necessity of always including reference nozzles in spray quality assessments to base classifications on relative rather than absolute values.
5
Shum, Sam C. K., Steve K. Johnson, Ho-Ming Pang e R. S. Houk. "Spatially Resolved Measurements of Size and Velocity Distributions of Aerosol Droplets from a Direct Injection Nebulizer". Applied Spectroscopy 47, n. 5 (maggio 1993): 575–83. http://dx.doi.org/10.1366/0003702934067108.
Testo completoAbstract (sommario):
Aerosol droplet sizes and velocities from a direct injection nebulizer (DIN) are measured with radial and axial spatial resolution by phase Doppler particle analysis (PDPA). The droplets on the central axis of the spray become finer and their size becomes more uniform when ≍ 20% methanol is added to the usual aqueous solvent. This could explain why the analyte signal is a maximum at this solvent composition when the DIN is used for inductively coupled plasma-mass spectrometry (ICP-MS). Mean droplet velocities are 12 to 22 ms−1 with standard deviations of ±4 to ±7 ms−1. The outer fringes of the aerosol plume tend to be enriched in large droplets. The Sauter mean diameter ( D3,2) and velocity of the droplets also vary substantially with axial position in the aerosol plume.
6
Glahn, A., M. Kurreck, M. Willmann e S. Wittig. "Feasibility Study on Oil Droplet Flow Investigations Inside Aero Engine Bearing Chambers—PDPA Techniques in Combination With Numerical Approaches". Journal of Engineering for Gas Turbines and Power 118, n. 4 (1 ottobre 1996): 749–55. http://dx.doi.org/10.1115/1.2816990.
Testo completoAbstract (sommario):
The present paper deals with oil droplet flow phenomena in aero engine bearing chambers. An experimental investigation of droplet sizes and velocities utilizing a Phase Doppler Particle Analyzer (PDPA) has been performed for the first time in bearing chamber atmospheres under real engine conditions. Influences of high rotational speeds are discussed for individual droplet size classes. Although this is an important contribution to a better understanding of the droplet flow impact on secondary air/oil system performance, an analysis of the droplet flow behavior requires an incorporation of numerical methods because detailed measurements as performed here suffer from both strong spatial limitations with respect to the optical accessibility in real engine applications and constraints due to the extremely time-consuming nature of an experimental flow field analysis. Therefore, further analysis is based on numerical methods. Droplets characterized within the experiments are exposed to the flow field of the gaseous phase predicted by use of our well-known CFD code EPOS. The droplet trajectories and velocities are calculated within a Lagrangian frame of reference by forward numerical integration of the particle momentum equation. This paper has been initiated rather to show a successful method of bearing chamber droplet flow analysis by a combination of droplet sizing techniques and numerical approaches than to present field values as a function of all operating parameters. However, a first insight into the complex droplet flow phenomena is given and specific problems in bearing chamber heat transfer are related to the droplet flow.
7
Zheng, Lei, Haizhou Xu, Hao Fu, Hua Chen e Wenlong Cheng. "Experiment and simulation study on the characteristics of pressure swirl nozzle flash spray under the influence of superheat". Journal of Physics: Conference Series 2683, n. 1 (1 gennaio 2024): 012036. http://dx.doi.org/10.1088/1742-6596/2683/1/012036.
Testo completoAbstract (sommario):
Abstract The good atomization performance of the pressure swirl nozzle makes it widely used in the fuel injection device of the internal combustion engine. Flash spray caused by fuel inlet superheat can affect spray and combustion characteristics. In this paper, a spray parameter measurement system is set up, combined with phase Doppler particle analysis (PDPA) technology to research the effect of superheat on spray velocity and droplet diameter distribution. To improve the safety of the experiment, Methyl Nonafluorobutyl Ether (HFE7100) with a boiling point of 61°C was used as the spray fluid. The cavitation model and VOF model are used to simulate the pressure swirl nozzle flash spray. The results show that when the temperature changes from 40°C to 60°C, the velocity of spray droplets increases and the particle size decreases under the action of weak evaporation; When the temperature changes from 60°C to 70°C, the evaporation mode is dominated by flash, making the droplet velocity at the spray center greatly increase and the velocity distribution change from saddle-shaped distribution to unimodal distribution. The droplet diameter increases, which may be due to the expansion of the droplet caused by the formation of bubbles inside the droplet under the action of flash.
8
Xu, Li. "Experimental Investigation on Atomization Characteristics of a Certain Type of Aero Engine Fuel Nozzle". Advanced Materials Research 354-355 (ottobre 2011): 468–71. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.468.
Testo completoAbstract (sommario):
The atomization characteristics of a certain type of aero engine fuel nozzle are discussed in this paper. The nozzle atomization characteristics have great influence on the combustion efficiency, ignition, outlet temperature field and pollution emissions. The flow characteristics, atomization particle size and distribution under different working conditions are obtained in this paper through the Phase Doppler particle analyzer and laser Doppler velocity system (PDPA / LDV). The test results show that to the dual pressure atomization nozzle, the flow rate range is wide and droplets size decreases with the increasing oil pressure, and tends to stabilize. The test data provide a reliable basis for the pressure atomizing nozzle design and modified.
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Wei, Xianggeng, Yiming Feng, Jinying Ye, Na Li e Oskar J. Haidn. "Influence of Mass Flow Rate on the Atomization Characteristics of Screw Conveyor Swirl Injectors". Aerospace 9, n. 6 (27 maggio 2022): 293. http://dx.doi.org/10.3390/aerospace9060293.
Testo completoAbstract (sommario):
This study conducted cold flow experimental research on the influence of mass flow rate on the atomization characteristics of screw conveyer swirl injectors in an opening environment. The Phase Doppler Particle Analyzer (PDPA) and high-speed photography were utilized to obtain experimental data. The results showed that the mass flow rate greatly influenced the atomization establishment and working characteristics of the injectors. The design point selection of the injectors exerted significant influence on the flow range and the performances of the injectors in a steady-state operation. The Sauter mean diameter of the atomization field continued to decrease with the increase in the mass flow rate. As the distance to the injector exit increased, the Sauter mean diameter continued to decrease, and finally tended to be stable. The average particle diameter obtained by the current image-processing method was greater than that by PDPA; therefore, the image-processing method needs improvement.
10
Bae, Ho Seuk, Won-Ki Kim, Su-Uk Son, Woo-Shik Kim e Joung-Soo Park. "An Estimation of the Backscattering Strength of Artificial Bubbles Using an Acoustic Doppler Current Profiler". Sensors 22, n. 5 (25 febbraio 2022): 1812. http://dx.doi.org/10.3390/s22051812.
Testo completoAbstract (sommario):
Acoustic Doppler current profilers (ADCPs) were developed to acquire water current velocities, as well as depth-dependent echo intensities. As the backscattering strength of an underwater object can be estimated from the measured echo intensity, the ADCP can be used to estimate plankton populations and distributions. In this study, the backscattering strength of bubble clusters in a water tank was estimated using the commercial ADCP as a proof-of-concept. Specifically, the temporal variations in the backscattering strength and the duration of bubble existence were quantitatively evaluated. Additionally, the PDSL (population density spectrum level) and VF (void fraction) of the artificial bubbles were characterized based on the obtained distribution characteristics using a PDPA (phase Doppler particle analyzer).
Tesi sul tema "Phase Doppler Particle Analysis (PDPA)"
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Vince, Maxence. "Analyses in situ et approche paramétrique du procédé Spray Flash Evaporation pour l’élaboration d’hexolites". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAE018.
Testo completoAbstract (sommario):
Les nanodiamants (NDs) font l'objet de recherches intenses dans les domaines biomédical, militaire et de la mécanique quantique. Pour produire ces NDs, le recours à la détonation d'un mélange RDX/TNT, aussi appelé hexolite, est souvent préféré. Cependant, pour produire des NDs aux propriétés physico-chimiques performantes, il est nécessaire d’avoir au préalable des particules fines d’hexolites, et des mélanges intimes et homogènes. Pour parvenir à cela, le laboratoire NS3E a développé le procédé de recristallisation par évaporation flash de spray (Spray Flash Evaporation, SFE). Cependant, l'influence des différentes conditions opératoires du procédé sur les caractéristiques physico-chimiques des particules est encore mal comprise. Améliorer cette compréhension permettrait une plus grande maîtrise des propriétés des particules recristallisées. Cette thèse vise donc, à l'aide d'analyses in situ telles que l'ombroscopie et le PDPA (Phase Doppler Particle Analyzer), à apporter des réponses. Les recherches se structurent en deux axes principaux. Le premier axe explore en profondeur les phénomènes physico-chimiques de l'évaporation flash d'un solvant (acétone) et l'impact du soluté (hexolite) sur le comportement du spray d'acétone. Le second axe porte quant à lui sur la caractérisation des particules d'hexolite, notamment en ce qui concerne leur sensibilité, leur taille et leur morphologie et les raisons qui ont conduit à de telles propriétés par rapport au comportement du sprayNanodiamonds (NDs) are the subject of extensive research in biomedical, military, and quantum mechanics applications. To produce these NDs, the detonation of a RDX/TNT mixture, commonly referred to as hexolite, is frequently employed. However, to achieve NDs with high-performing physicochemical properties, it is essential to begin with finely divided hexolite particles and to ensure that the mixture is both intimate and homogeneous. In pursuit of this goal, the NS3E laboratory has developed a recrystallization process based on Spray Flash Evaporation (SFE). Despite this advancement, the influence of various operating conditions on the physicochemical characteristics of the resulting particles remains poorly understood. Gaining a deeper understanding of these influences would enable more precise control over the properties of the recrystallized particles. This thesis therefore aims to address these issues by employing in situ analytical techniques, such as shadowgraphy and Phase Doppler Particle Analysis (PDPA).The research is organized around two principal axes. The first focuses on an in-depth investigation of the physicochemical phenomena underlying the flash evaporation of a solvent (acetone) and examines how the presence of a solute (hexolite) affects the behavior of the acetone spray. The second axis centers on characterizing the resulting hexolite particles—specifically their sensitivity, size, and morphology—and elucidating the underlying reasons for these properties considering the spray’s behavior
2
FLOHRE, NICHOLAS MATTHEW. "EXPERIMENTAL INVESTIGATION OF SPRAY ATOMIZATION PROPERTIES OF AN AIRCRAFT ENGINE SWIRL CUP". University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054322000.
Testo completo
3
Bultynck, Hervé. "Développements de sondes laser Doppler miniatures pour la mesure de particules dans des écoulements réels complexes". Rouen, 1998. http://www.theses.fr/1998ROUES031.
Testo completoAbstract (sommario):
Le diagnostic par des méthodes optiques basées sur l'anémométrie Doppler laser ou phase Doppler permet une meilleure connaissance des écoulements diphasiques. Cependant, l'encombrement de tels systèmes optiques limite leur utilisation. Grâce à la théorie de Lorenz-Mie généralisée, la dimension finie des faisceaux peut être prise en compte, ainsi, deux sondes laser Doppler miniatures ont pu être réalisées. Le développement d'une sonde phase Doppler miniature en rétrodiffusion est au centre de la première partie de cette thèse. L'originalité d'une telle sonde réside dans l'utilisation d'une seule lentille pour la focalisation des faisceaux incidents et la collection de la lumière diffusée. Différentes géométries correspondant a plusieurs modes de diffusion sont présentées. Pour chacune de ces configurations, un traitement de signal spécifique a été développé. La méconnaissance des mécanismes liés à la resuspension nécessite de nouveaux systèmes de mesures. La seconde partie de ce travail décrit donc la conception et la réalisation d'une sonde couplée ADL (Anémométrie Doppler Laser) et DCW (Dual Cylindrical Waves) permettant la mesure simultanée de la vitesse et de la hauteur de particules dans une couche limite turbulente. Cette technique repose sur la superposition de deux volumes de mesures optiques de longueurs d'onde différentes, le premier à franges parallèles (ADL) et le second à franges en éventail (DCW). Un code d'acquisition et de traitement a été développé pour faciliter les mesures, en particulier il indique la vitesse et la hauteur des particules traversant le volume de mesure en fonction du temps de mesure.
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Onofri, Fabrice. "Prise en compte de la dimension finie des faisceaux d'éclairage en granulométrie optique : anémométrie phase Doppler. diagnostics des milieux diphasiques". Phd thesis, Université de Rouen, 1995. http://tel.archives-ouvertes.fr/tel-00287923.
Testo completoAbstract (sommario):
Le diagnostic par une méthode optique telle que l'anémométrie phase Doppler, des particules présentes dans les milieux diphasiques, nécessite l'emploi de faisceaux laser focalisés. La compréhension et l'élimination des effets engendrés sur les mesures de taille, par les gradients d'éclairage ou les « effets de trajectoire », est au centre de la première partie de cette thèse. Différentes solutions, testées numériquement et expérimentalement, sont proposées pour éliminer les biais constatés. L'extension de l'anémométrie phase Doppler à la mesure de la partie réelle et complexe (absorption) de l'indice de réfraction des particules est ensuite considérée. Les méthodes originales proposées autorisent, en plus des mesures de taille et de vitesse, la reconnaissance des particules par leur indice, l'étude de la coalescence de gouttes (liquides transparents ou absorbants) ou la détection des fortes variations de température de particules. La dernière partie de ce travail propose diverses solutions pour étendre l'anémomètrie phase Doppler à la mesure de particules cylindriques (fibres, jets liquides), ovoïdes (oblates/problates), sphériques nonhomogènes (multicouches, à coeur, hétérogènes: diphasiques ou non) et irrégulières. Le cas des particules multicouches est particulièrement détaillé, à partir de simulations basées sur le travail théorique effectué pour étendre la théorie de Lorenz-Mie généralisée à ce type de particules.
5
Onofri, Fabrice. "Prise en compte de la dimension finie des faisceaux d'éclairage en granulométrie optique : anémométrie phase Doppler. diagnostics des milieux diphasiques". Phd thesis, Rouen, 1995. https://tel.archives-ouvertes.fr/tel-00287923.
Testo completoAbstract (sommario):
Le diagnostic par une méthode optique telle que l'anémométrie phase Doppler des particules présentes dans les milieux diphasiques, nécessite l'emploi de faisceaux laser focalisés. La compréhension et l'élimination des effets engendrés par les gradients d'éclairage ou effets de trajectoire sur la mesure de la taille des particules sphériques est au centre de la première partie de cette thèse. Différentes solutions, testées numériquement et expérimentalement, sont proposées pour éliminer les biais constatés. L'extension de l'anémométrie phase Doppler à la mesure de la partie réelle et complexe (absorption) de l'indice de réfraction des particules est ensuite considérée. Les méthodes originales proposées autorisent en plus des mesures de taille et de vitesse, la reconnaissance des particules par leur indice, l'étude de la coalescence de gouttes (liquides transparents ou absorbants) ou la détection des fortes variations de température des particules. La dernière partie de ce travail propose diverses solutions pour étendre l'anémométrie phase Doppler à la mesure de particules cylindriques (fibres, jets liquides), ovoïdes (oblates/problates), sphériques non homogènes (multicouches, à coeur, hétérogènes: diphasiques ou non) et irrégulières. Le cas des particules multicouches ou à coeur simple, est particulièrement détaillé, ceci à partir de simulations basées sur le travail théorique effectué pour étendre la théorie de Lorenz-Mie généralisée au cas des particules multicouches
Libri sul tema "Phase Doppler Particle Analysis (PDPA)"
1
United States. National Aeronautics and Space Administration., a cura di. Analysis of counting errors in the Phase/Doppler particle analyzer. [Washington, D.C.]: National Aeronautics and Space Administration, 1987.
Cerca il testo completoCapitoli di libri sul tema "Phase Doppler Particle Analysis (PDPA)"
1
Bachalo, W. D. "The Phase Doppler Method: Analysis and Application". In Optical Particle Sizing, 283–99. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4757-1983-3_23.
Testo completoAtti di convegni sul tema "Phase Doppler Particle Analysis (PDPA)"
1
Lee, Jin-Woo, Kuk Jin Jung, Morely Sherman, Hyun Sin Kim e Youn-Jea Kim. "Experimental and Numerical Analysis on the Performance of Spiral Two-Fluid Atomizer Using DPM Method". In ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20350.
Testo completoAbstract (sommario):
Abstract A two-fluid atomizer has been frequently used in a wide range of industries for various purposes such as painting, cleaning particles and snow making. In particular, the manufacturing of advance semiconductors using sensitive devices such as organic light emitting diodes (OLED) and dynamic random access memory (DRAM), require high performance nozzle. The droplets sprayed with a high relative gas velocity are widely used for cleaning particles. In this paper, two-fluid atomizer is numerically studied according to four variables to confirm the effect on the atomizer performance. The numerical results using the discrete phase model (DPM) with several break-up models are compared with the experimental data measured by the phase doppler particle analyzer (PDPA). Design of experiment (DOE) and genetic algorithm (GA) were used to obtain design points, and conduct sensitivity analysis, respectively. The results showed that the WAVE model has a good agreement compared to the other models, and the orifice diameter is a crucial factor for this model to determine the performance of Weber number and pressure.
2
Sasao, Yasuhiro, Ryo Takata, Satoshi Miyake, Soichiro Tabata e Satoru Yamamoto. "Optical Coarse Droplet Measurement and Wet Loss Analysis on the Wet Air Flow Through the Subsonic Blade Cascade Channel". In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91928.
Testo completoAbstract (sommario):
Abstract In order to understand the details of the mechanism of the occurrence of wetness loss between blade rows, the blades of an HP nuclear turbine were modeled in an atmospheric subsonic wind tunnel, and a flow field with wet loss was analyzed in its totality using a three-hole Pitot tube and Phase Doppler Particle Analyzer (PDPA) system. In the secondary flow loss region and the end wall loss region, a significant increase in pressure loss was confirmed under wet conditions. Analysis by measurement and the Eulerian-Lagrangian coupled solver showed that these loss increases can occur due to the agitation of water droplets and water films in the passage vortex or corner vortex. Finally, this report contains a breakdown of profile loss, thermodynamic loss and acceleration loss of the wet air flow through the sub-sonic blade row.
3
Glahn, A., M. Kurreck, M. Willmann e S. Wittig. "Feasibility Study on Oil Droplet Flow Investigations Inside Aero Engine Bearing Chambers: PDPA Techniques in Combination With Numerical Approaches". In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-100.
Testo completoAbstract (sommario):
The present paper deals with oil droplet now phenomena in aero engine bearing chambers. An experimental investigation of droplet sizes and velocities utilizing a Phase Doppler Particle Analyzer (PDPA) has been performed for the first time in bearing chamber atmospheres under real engine conditions. Influences of high rotational speeds are discussed for individual droplet size classes. Although this is an important contribution to a better understanding of the droplet flow impact on secondary air/oil system performance, an analysis of the droplet flow behaviour requires an incorporation of numerical methods because detailed measurements as performed here suffer from both strong spatial limitations with respect to the optical accessibility in real engine applications and constraints due to the extremely time consuming nature of an experimental flow field analysis. Therefore, further analysis is based on numerical methods. Droplets characterized within the experiments are exposed to the flow field of the gaseous phase predicted by use of our well-known CFD code EPOS. The droplet trajectories and velocities are calculated within a Lagrangian frame of reference by forward numerical integration of the particle momentum equation. This paper has been initiated rather to show a successful method of bearing chamber droplet flow analysis by a combination of droplet sizing techniques and numerical approaches than to present field values as a function of all operating parameters. However, a first insight into the complex droplet flow phenomena is given and specific problems in bearing chamber heat transfer are related to the droplet flow.
4
Tolpadi, Anil K., David L. Burrus e Robert J. Lawson. "Study of Two-Phase Flow Downstream of a Gas Turbine Combustor Dome Swirl Cup". In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-392.
Testo completoAbstract (sommario):
The two-phase axisymmetric flowfield downstream of the swirl cup of an advanced gas turbine combustor is studied numerically. The swirl cup analyzed is that of a single annular GE/SNECMA CFM56 turbofan engine that is comprised of a pair of coaxial counter-swirling air streams together with a fuel atomizer. The atomized fuel mixes with the swirling air stream resulting in the establishment of a complex two-phase flowfield within the swirl chamber. The analysis procedure involves the solution of the gas phase equations in a Eulerian frame of reference. The flow is assumed to be nonreacting and isothermal. The liquid phase is simulated by using a droplet spray model and by treating the motion of the fuel droplets in a Lagrangian frame of reference. Extensive Phase Doppler Particle Analyzer (PDPA) data for the CFM56 engine swirl cup has been obtained at atmospheric pressure by using water as the fuel (Wang et al., 1992a). This includes measurements of the gas phase velocity in the absence and presence of the spray together with the droplet size, droplet number count and droplet velocity distribution information at various axial stations downstream of the injector. Numerical calculations were performed under the exact inlet and boundary conditions as the experimental measurements. The computed gas phase velocity field showed good agreement with the test data. The agreement was found to be best at the stations close to the primary venturi of the swirler and to be reasonable at later stations. To compare the droplet data, a numerical PDPA scheme was formulated whereby several sampling volumes were selected within the computational domain. The trajectories of various droplets passing through these volumes were monitored and appropriately integrated. The calculated droplet count and mean droplet velocity distributions were compared with the measurements and showed very good agreement in the case of larger size droplets and fair agreement for smaller size droplets.
5
Levy, Y., V. Erenburg, V. Sherbaum, V. Ovcharenko e A. Roizman. "The Use of Methanol as an Alternative Fuel: Droplet Formation and Evaporation". In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42965.
Testo completoAbstract (sommario):
Methanol, produced from natural may be considered as an alternative fuel for fossil based liquid fueled gas turbines, especially for land based systems. In the present work, the effect of physical properties of methanol and kerosene on atomization and evaporation are compared. The spray’s liquid flux, droplet sizes and droplet velocities, cone angle were measured using Phase Doppler Particle Analyzer/Laser Doppler Velocimeter (TSI PDPA/LDV) system. Water, kerosene and ethanol (ethanol instead of methanol was used due to the toxicity of methanol) were used and tested at the same input liquid pressures. Analytical analysis of evaporation time for a single droplet of kerosene and methanol showed that the evaporation time is about the same for two fuels with the same droplet diameters. However, due the methanol’s lower calorific value and the fact that its volume flux must be more than twice as much (for similar thermal power), its corresponding evaporation time is longer than for kerosene. The evaporation time for kerosene and methanol, which took into accounts that more methanol should be evaporated, was simulated by CFD. The simulation results showed that methanol spray requires significantly longer distance than kerosene. Thus, the spray of methanol has larger droplet diameter than kerosene and prolonged evaporation time.
6
Gupta, Abhishek Kumar, Keshav Yadav, Surendra Kumar Soni, Yogeshwar Nath Mishra e Santanu De. "Effects of the Swirl Field on the Structure, Planner Drop Sizing and Large-Scale Instabilities of Flow-Blurring Spray". In ASME 2023 Gas Turbine India Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gtindia2023-118555.
Testo completoAbstract (sommario):
Abstract Effective atomisation is a governing parameter in a liquid-based gas turbine. Incorporating the swirling air with the spray influences the spray structure, drop dispersion, and large-scale unsteadiness. Therefore, reliable measurement of drop sizes, spray structure, and large-scale instabilities are necessary for the detailed analysis of the complex interaction of the spray droplets in the swirl airfield. We aim to investigate the spray structure, drop sizing, and large-scale unsteadiness of a flow-blurring (FB) spray under swirl airfield conditions. In previous studies, the drop size distribution in FB sprays in a stagnant medium has been characterized based on the point measurement tool, namely Phase Doppler Particle Analyzer (PDPA). However, the PDPA measurement is time-consuming, suffers issues related to multiple scattering in the dense region of the spray, and provides only the time-averaged statistics. Herein, we characterize FB spray under the influence of an external swirling air stream using structured laser illumination planar imaging (SLIPI) technique. The SLIPI technique eliminates unwanted optical signals due to the multiple scattering and provides shot-to-shot variations of the drop size mapping and spray structure. A lab-scale experimental setup consisting of a centrally mounted FB atomiser with co-annular swirl air passage is operated at a fixed air-liquid mass ratio but with different swirl velocities. Following 1p-SLIPI technique, simultaneous Mie and LIF signals are recorded using two cameras, which are eventually used to obtain two-dimensional droplet Sauter mean diameter (SMD) contours. The calibration constant for the LIF/Mie ratio is deduced using PDPA measurements. The ensemble of instantaneous images is utilized for the proper orthogonal decomposition (POD) analysis to investigate the spatio-temporal features of the large-scale structure. The role of the swirling air on the different types of large-scale instabilities is explained based on the POD modes and energy contributions by the individual modes.
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Schnitzler, J. P., I. von Deschwanden, S. Clauss, F. K. Benra, H. J. Dohmen e K. Werner. "Experimental Determination of a Four Stage Axial Compressor Map Operating in Wet Compression". In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-26807.
Testo completoAbstract (sommario):
Injecting water in the air upstream of an axial compressor intake is an effective method to increase the efficiency and the power output of a gas turbine application especially at hot days. Reasoned by their complex two phase flow axial compressors which operate in wet compression mode are in the focus of present thermodynamic analysis, numerical investigations and experimental research. Recently the evaporation process of water droplets, especially at high temperature and pressure levels has been investigated with the laser based measurement technique Phase Doppler Particle Analyzer (PDPA) in detail in a stationary test rig at the University of Duisburg-Essen. The focus of these investigations has been laid on the analysis of the evaporation process in a free stream or cross flow behavior without droplet wall interaction. In this paper the first results of the novel four stage axial compressor test rig are published. This test rig is arranged for high amount of water injection with special optical access for laser based measurements. The first part of the paper outlines the general design, geometric facts and aerodynamic reference parameters of the test rig and gives an introduction to the installed conventional measurement technique. Discrete measurement results from dry runs are compared with CFD results to validate the gathered experimental data. In the second part of the paper the previously discussed dry runs are compared with measurement results of runs with water injection. The amount of water to air ratio is varied and the effects on the operating behavior of the four stage axial compressor are pointed out in detail. Furthermore results from the laser based PDPA measurements at the inlet and at the outlet of the compressor outline the impact on the water droplets moving through the compressor in wet compression mode.
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Clauss, S., J. P. Schnitzler, B. Barabas, P. S. Nagabhushan, F. K. Benra e H. J. Dohmen. "Test Rig Design to Explore Water Droplet Behavior in a Four Stage Axial Compressor". In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-63429.
Testo completoAbstract (sommario):
The efficiency of gas turbine cycles can be enhanced by many applications and combinations according to the choice of the thermodynamic cycle. Gas turbine cycles which operate with humid air and water injection at different locations of the compressor are in the focus of present thermodynamic analysis and experimental research. Reasoned by their high potential in efficiency and power output augmentation, they have been implemented on many industrial gas turbines. The evaporation process of water droplets, especially at high temperature and pressure levels has been recently investigated with the laser based measurement technique Phase Doppler Particle Analyzer (PDPA) in detail in a stationary test rig at the University of Duisburg-Essen. The focus of these investigations was on the analysis of the evaporation process in a free stream or cross flow without droplet wall interaction [1–5]. In this paper the development of a novel four stage axial compressor test rig which is designed for water injection will be introduced and results of numerical investigations will be presented. This test rig has been designed to adopt the results from the stationary test rig to a real compressor. The first part of the paper deals with the mechanical and aerothermodynamic design of the test rig. Certain design parameters, the optical access for the PDPA measurements and a comparison between numerical and experimental results without water injection are outlined. In the second part of the paper, first comparative results from numerical investigations of the compressor performance in dry and wet compression operating conditions are presented. Furthermore, numerical results for droplet wall interaction in the four stage axial compressor are shown. This analysis outlines the need for further experimental research in the future to validate numerical methods with accurate droplet wall interaction behavior in turbomachines.
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Chaine, G., e D. E. Nikitopoulos. "Multiphase Digital Particle Image Velocimetry in a Dispersed, Bubbly, Axisymmetric Jet". In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31435.
Testo completoAbstract (sommario):
A particle image velocimetry (PIV) technique developed for application to two-phase flows is presented and validated. The technique is capable of simultaneously measuring carrier and bubble phase velocities on a plane. The validation experiments have been conducted in a vertical upwards, two-phase (water-air) bubbly jet flow at a Reynolds numbers of 5,673 and 11,345 and low bubble concentration matching the experiments of Stanley and Nikitopoulos (1998). Comparisons with measurements obtained by Stanley and Nikitopoulos (1998) using Phase Doppler Analysis (PDA) experiments indicate that the agreement between the two techniques is very satisfactory (deviations of the order of 5%) for both single-phase and two-phase jet carrier-flow velocities. In addition, bubble phase velocity measurements obtained from backlit visualizations of the bubbly jet flow using the bubble-tracking method of Fiedler et al. (2001) are successfully compared to those obtained from PIV. The PIV study confirms that bubbles experience a substantial deceleration in the unmixed core of the jet near field and illustrates carrier-phase mean-flow modification consistent with past point-wise measurements.
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Wang, Ting, e Lei Zhao. "Development of an Experimental Test Facility for Investigating Mist/Air Film Cooling Application in Gas Turbine Airfoils". In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94476.
Testo completoAbstract (sommario):
Film cooling is a cooling technique widely used in high-performance gas turbines to protect the turbine airfoils from being damaged by hot flue gases. Motivated by the need to further improve the turbine hot section cooling performance, a new cooling scheme, mist/air film cooling is investigated. A small amount of tiny water droplets with an average diameter about 7 μm (mist) is injected into the cooling air to enhance the cooling performance. One key feature in understanding mist cooling is the ability to capture droplet information. This paper presents the experimental facility and instrumentation of a mist/air film cooling study with both heat transfer and droplet measurements. A wind tunnel system and test facilities are built. A Phase Doppler Particle Analyzer (PDPA) system is employed to measure the two-phase flow characteristics, including droplet size, droplet dynamics, velocity, and turbulence. Infrared camera and thermocouples are both used for temperature measurements. An extensive uncertainty analysis is performed to assist in identifying large uncertainty sources and planning for experimental procedure. It was found during the experiment design process that resolving the mist agglomeration problem is the key in successfully generating a well-controlled mist/air mixture and reducing experimental uncertainties. The test apparatus has proven to serve the purpose well to investigate mist/air film cooling with both heat transfer and droplet measurements. Selected experimental data is presented.
Rapporti di organizzazioni sul tema "Phase Doppler Particle Analysis (PDPA)"
1
Edwards, C. F., e K. D. Marx. Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint. Office of Scientific and Technical Information (OSTI), giugno 1991. http://dx.doi.org/10.2172/6168463.
Testo completo
2
Svedeman. L51729 Gas Scrubber Performance Evaluation - Measurement Methods. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), aprile 1995. http://dx.doi.org/10.55274/r0010420.
Testo completoAbstract (sommario):
Scrubbers and separators are used in natural gas pipelines to remove solid and liquid materials from the gas stream. Failure to remove the entrained materials from the gas can result in equipment damage, increased pressure drop due to liquid accumulation, flow measurement errors, and corrosion. The performance of separators is rarely tested after a separator is installed because there is a lack of test instrumentation and it is difficult to conduct tests at the high pressures. The only indicators of poor separator performance are recurring problems in downstream equipment or the detection of accumulated materials in downstream piping. Instrumentation is needed that can verify separator performance when the unit is installed and to periodically monitor separator performance. The report documents results of instrument tests. The objectives of the instrument evaluations were to verify that the instruments could be used to measure particles penetrating a separator, to provide a comparative evaluation of the instruments, and to identify any measurement problems that could be encountered in field testing. One important result was that the separator minimum removable drop size increased as the operating pressure increased. This trend is not generally known, since there is a lack of test results for pressures above atmospheric pressure. The separator performance test results are documented in this report. Two different particle measuring instruments were evaluated for documenting separator performance. The two instruments were the video imaging system with automatic image analysis and the laser-based phase Doppler particle measuring system. The instruments were evaluated in laboratory tests that were conducted on a commercially available vane-type separator. The objectives of the instrument evaluations were to verify that the instruments could be used to measure particles penetrating a separator, to provide a comparative evaluation of the two instruments, and to identify any measurement problems that could be encountered in field testing. The video imaging system has a number of attractive attributes, but it was not able to measure the small diameter drops at the separator exit. The primary limitation was that the optical system could not clearly image the small drops (in the range from 5 to 30 um). The phase Doppler particle measuring system was capable of measuring all of the parameters needed to document the separator performance. Based on the instrument evaluations, future efforts on developing measurement methods for documenting separator performance should focus on adapting the phase Doppler system to field testing.