Wyniki wyszukiwania - BazTech

1

Laser based diagnostic system for spray measurements

Kapusta Ł. J., Jaworski P., Teodorczyk A., Kowalski J.

Journal of KONES

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2015

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Vol. 22, No. 3

91--98

EN

The paper discusses the capabilities of the laser diagnostic system for dispersed multiphase flows measurements, which was recently commissioned at the Institute of Heat Engineering (ITC) at Warsaw University of Technology. The system presented in the paper is multifunctional and is capable to use different measurements techniques such as shadowgraphy, Mie scattering (scattering on the gas-liquid interface) and LIF (laser induced fluorescence). It provides possibility of switching from one technique to another depending on the characteristics of the observed combustion/injection mixing process. The operational features are discussed in-detail. The study presents the required and possible system setups. Special attention was focused on the system components, which are needed for relevant measurement techniques. Moreover, the limitations of the measurement techniques are discussed and the example measurements are presented. The study shows that using different techniques extends the measurement capabilities of the system with minimum investment costs. This results from the fact that certain system components for different techniques are the same. Moreover, one can conclude that the system design allows certain measurement methods to be applied simultaneously, which results in synergy by making possible drawing more advanced conclusions on observed phenomena

2

Investigation of natural convection in cubical enclosure using laser induced fluorescence

Kraszewska A., Donizak J., Jaszczur M.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2014

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z. 86 [290], nr 3

401--408

EN

Temperature measurements are extremely important and they are used in many technical and engineering processes, including the analysis of natural convection. In contrast to the commonly used thermocouples and Pt100 temperature sensors, which allow point temperature measurements, laser induced fluorescence technique (LIF) allows the imaging of temperature fields throughout the area. An obvious disadvantage of thermocouples and Pt100 sensors is the possibility that the probes can affect the fluid flow, changing its structure. This problem does not appear in LIF measurements and better accuracy of temperature mapping is obtained. This work focuses on describing one-color LIF technique (using one fluorescent dye) in theoretical and practical terms. The experimental set-up is described, as well as a number of operations required to get the temperature field of the whole domain. The results of the natural convection process analysis in the configuration of one side wall heated and the opposite one cooled, with the use of laser induced fluorescence technique are presented.

PL

Pomiary temperatury są niezwykle istotne i mają zastosowanie w wielu technicznych i inżynieryjnych procesach, m.in. w analizowaniu konwekcji naturalnej. W odróżnieniu od popularnie używanych termopar i sensorów temperatury Pt100, pozwalających na punktowe pomiary temperatury, technika fluorescencji laserowej LIF pozwala na zobrazowanie pola temperatury w całym badanym obszarze. Oczywistą wadą termopar i czujników Pt100 jest możliwy wpływ sondy na przepływ płynu, zmieniając jego strukturę. Ponadto na dokładność pomiarową w technice LIF wpływa tak że fakt, że w układzie nie występują zaburzenia przepływu spowodowane wprowadzeniem do analizowanego obszaru stałych czujników. Problem ten nie pojawia się w pomiarach techniką LIF. Ponadto, odwzorowanie temperatury jest bardziej dokładne przy pomiarach techniką fluorescencji laserowej. Poniższa praca skupia się na opisaniu jednokolorowej techniki LIF (z wykorzystaniem jednego barwnika fluorescencyjnego) pod względem teoretycznym oraz praktycznym. Opisane zostało stanowisko pomiarowe oraz szereg kolejnych operacji składających się na uzyskanie obszarowego pola temperatury. Przedstawione zostały wyniki analizy procesu konwekcji naturalnej wody w konfiguracji z jedną ścianą boczną grzaną i naprzeciwległą chłodzoną poprzez zamieszczenie wyników pomiarowych uzyskanych techniką fluorescencji laserowej.

3

Measurement of turbulent mixing usind PIV and LIF

Aanen L., Telesca A., Westerweel J.

Machine Graphics and Vision

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1999

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Vol. 8, No. 4

529-543

EN

Experimental investigation of turbulent mixing requires the simulataneous measurement of the instantaneous velocity and concentration fields. The velocity is measured by means of particle image velocimetry (PIV), and the concentration by means of laser induced fluorecence (LIF). A combined measurement technique was developed in which we use PIV and LIf simulataneously, without influecing each other. To test the reliability and precision of the technique we took measurements on the mixing of a point source placed at the centerline of a fully-developed turbulent pipe-flow. The experimental results mixing of a point source in homogeneous turbulentce. The agreement with the experimental tesults is satisfactory, although three ramains a small deficit in the mass-balance equation. It is conjectured that is due to the finite resolution of the experimental data and the high intermittency of the concentration.