17th International Symposium on Application of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, July 07 – 10, 2014 Experimental Facility The experimental investigations were carried out using a closed-loop water tunnel, which had a measurement sect Experimental studies on particle-laden jet by the use of pulsed LED in a PIV/PLIF System (see Fig. 1) consisting of a transparent square channel with the dimensions 1000 mm x 100mm x 100 mm for the cro flow. The round jet duct had a diameter of dj = 11 mm. The experiments were realized at a constant velocity ratio R L. Pasternak, M. Sommerfeld with Rec= 50,000 (cross-flow), Rej=12,970 (jet) and a water temperature of 23°C. To ensure a constant flow rate, Mechanische Verfahrenstechnik, Martin-Luther-Universitä t Halle-Wittenberg, Halle (Saale), Germany Figurepumps 1. Schematic diagram thehauled jet in cross-flow experimental arrangement circular casing (not shown in Fig.of1) a higher flow rate as necessary for the measurements in th * Correspondent authors: [email protected], [email protected] respective vessel. Each flow was controlled by an electromagnetic flow sensor and a manual control valve (not sho The variation of the particle`s Stokes-number was realised by the use of particles with different densities and sizes. In in Fig. 1). jet, PIV/PLIF, pulsed LED Keywords: Particle-lade order to use these non-fluorescent particles for PLIF, the coating with an acrylic lacquer mixed with Rhodamin in a In the present work, the influence of a particle-laden jet heated fluidized bed was essential. The PIV / PLIF system consisted first of two 1280 x 1024 Pixel PCO Sensicam issuing a cross-flow was investigated in order to assess the turbulent mixing progress for particles withdouble different Stokesshutter CCD cameras, which were aligned by using a beam splitter (see Fig. 2). To ensure high resolution number. In the experimental configuration, a turbulent round jet was injected perpendicularly into aimages, fully developed the image resolution was 9.81 µm/Pixel. This was accomplished by two identical ojectives Rodagon f75/4.5 turbulent cross-flow through a square channel. To avoid 95 mm extension influences from the pumps and to ensure with a constant flow tube. The band-pass filters ensured a separate recording of the jet fluid and the particles. For the rate, the jet and the cross-flow were fed by static pressure tracer in Reynolds the jet fluid a 532 nm band-pass interference filter from a Nd-YAG laser was deployed. The fluorescen from separate storage tanks with overflow. The number (Re ) determined the jet diameter was 12,970 and the particlesThe were recorded with a 550equipment nm long-pass entire measurement wasfilter. synchronized and operated by a TTL pulse-generator, which contr velocity-ratio jet to cross-flow was R = 3. Different particle Fig. 1 Schematic diagram of the jet in cross-flow sizes and densities were used to achieve Stokes-numbers Figure 1. Schematic diagram ofwith the jeta inMOSFET cross-flowand experimental arrangement camera and the LEDexperimental light sheet. In arrangement. combination a constant power-supply with puls between 0 - 10. The measurements were performed by using Particle Image Velocimetry (PIV) applying two double image higher than 20 µs, the LED generated enough luminous intensity to conduct the PIV / PLIF measur variation CCD-cameras with identical focal planes. Instead of The using a of the particle`s Stokes-number was realised by the use of particles with different densities and sizes. pulse laser for the light sheet, a focusable fibre-optic LED linewith the PCO cameras. Through post-processing all out-of focus particles from the boundary o combination order to use these non-fluorescent particles for PLIF, the coating with an acrylic lacquer mixed with Rhodamin i light source with time control was developed. The minimum width of the light sheet was 1.2 mm at a maximum working sheetheated and depth of field of the cameras by a LOG-image The pre-processed were fluidized bed was essential. Thewere PIV removed / PLIF system consisted firstfilter. of two 1280 x 1024 Pixelimages PCO Sensic z distance of 120 mm. In order to avoid in-motion undouble shutter CCD cameras,Difference which were aligned(MQD) by using a beam splitter (see Fig.of2).the Tojetensure high resolut sharpness in the images the maximum pulse duration of Minimum the using the Quadratic method to determine the velocity and particles [1] y LED light sheet was 30 !s. In order to determine velocity x images, the image resolution was 9.81 µm/Pixel. This was accomplished by two identical ojectives Rodagon f75/ information from the jet fluid and the particles, the Fig. 2 Schematic diagram of the technical camera setup application of fluorescent particles was required. with For 95the Figure 2. Schematic diagram of the technical mm extension tube. The band-pass filters ensured a separate recording camera of the jetsetup fluid and the particles. For Results and Discussions determination of the jet fluid velocity the water was seeded Results tracer in the jet fluid a 532 nm band-pass interference filter from a Nd-YAG laser was deployed. The fluoresc with 40 !m non-fluorescent PMMA tracers. The clear To verifywas the light intensity distribution of the LED light sheet, the jet was seeded with non-fluorescent 40 µ separation between the jet fluid and the particles To verify the light intensity distribution of the LED light were recorded with a 550 nm long-pass filter. enabled by a band-pass interference filter for theparticles tracer sheet, thestep jet is was seeded with3.non-fluorescent 40 light !m intensity PMMAdistribution th tracers. The result of this first plotted in Figure With a non-uniform detection and a long-pass filter for the particles. Due to the tracers. The result of this first step is plotted in Figure 3. With lower available light intensity in relation to a pulse laser, a non-uniform light distribution the number distribution profile would show, contrary to Fig. 3,intensity obvious deviations from the expected jet concentration pro lenses with a depth of field with 1 mm were deployed. distribution profile would show, contrary to Fig. 3, obvious deviations from the expected jet concentration profile. j Experimental Setup The experimental investigations were carried out using a z closed-loop water tunnel, which had a measurement section (see Fig. 1) consisting of a transparent square channel with y x the dimensions 1000 mm x 100mm x 100 mm for the crossflow. The round jet duct had a diameter of d = 11 mm. The Figure 2. Schematic diagram of the technical camera setup experiments were realized at a constant velocity ratio R=3 with Re = 50,000 (cross-flow), Re =12,970 (jet) and a water temperature of 23°C. To ensure a constant flow rate, the circular casing pumps (not shown in Fig. 1) hauled a higher flow rate as necessary for the measurements in their respective vessel. Each flow was controlled by an electromagnetic flow sensor and a manual control valve (not Fig. 3 Vertical tracer number distribution profile.profile Figure 3. Vertical tracer number distribution shown in Fig. 1). The variation of the particle`s Stokes-number was realised Summary by the use of particles with different densities and sizes. In order to use these non-fluorescent particles forSummary PLIF, the and Conclusions The first experiments proved the possibility of the coating with an acrylic lacquer mixed with Rhodamin in a application of pulsed LED as lightofsheet in combined The first experiments proved the possibility of the application pulsedsource LED as light sheet source in combine heated fluidized bed was essential. The PIV / PLIF system PIV and PLIF measurements. Due to the high current, the consisted first of two 1280 x 1024 Pixel PCO Sensicam double wavelength ofcurrent, the Luminus CBT-90 LED shifted from LED 535 nm PLIFameasurements. Due to the high the wavelength of the Luminus CBT-90 shifted from 535 shutter CCD cameras, which were aligned by using beam below the characteristic transmission bandwidth of the filter. splitter (see Fig. 2). To ensure high resolution images, the the characteristic transmission bandwidth of the filter. Hence, low brightness the tracer images turned o Hence, the low brightness of thethe tracer images ofturned out image resolution was 9.81 !m/Pixel. This was accomplished into an issue. In order to increase brightness in the tracer by two identical ojectives Rodagon f75/4.5 with 95 mm issue. In order to increase brightness in the tracerof images, a substitutioninterference of the band-pass interference filter is images, a substitution the band-pass filter is extension tube. The band-pass filters ensured a separate necessary. In addition, an adjustment of the cameras in recording of the jet fluid and the particles. For the tracer in In addition, an adjustment of the cameras compliance with the lightangle scattering the tracer particle compliance with inthe light scattering of angle the of tracer the jet fluid a 532 nm band-pass interference filter from a Ndparticles will take place. YAG laser was deployed. The fluorescent particles were place. This work is in progress and final results will be presented at the symposium. recorded with a 550 nm long-pass filter. j c j REFERENCES [1] Bröder D, Sommerfeld M “An advanced LIF-PLV system for analysing the hydrodynamics in a laboratory bubble column at fractions” Exp in Fluids 33 (2002) pp.826-837 3.12.5 [2] Willert C, Stasicki B, KlinnerJ, Moessner1S “Pulsed operation of high-power light emitting diodes for imaging flow velocim Sci. Technol. 21 (2010)