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The 26 th Annual Meeting of the Israeli Association of Aerosol Research Tuesday, May 21 st , 2013

Characterization of the ethanol–water spray generated by pressure assisted nozzle Vitali Ovcharenko and Yeshayahou Levy Turbo and jet Engine Laboratory Faculty of Aerospace Engineering, Technion , Haifa. The 26 th Annual Meeting of the Israeli Association of Aerosol Research

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The 26 th Annual Meeting of the Israeli Association of Aerosol Research Tuesday, May 21 st , 2013

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  1. Characterization of the ethanol–water spray generated by pressure assisted nozzleVitaliOvcharenko and YeshayahouLevyTurbo and jet Engine LaboratoryFaculty of Aerospace Engineering, Technion, Haifa The 26th Annual Meeting of the Israeli Association of Aerosol Research Tuesday, May 21st, 2013 Diaspora Museum (בית התפוצות), TAU

  2. Introduction There is a potential to directly burn water-soluble fuels (algae), heavily diluted with water, to generate a steam.To evaluate the feasibility of this concept, a mix of ethanol and water simulates the renewable fuels will be used in a swirl-stabilized burner.A pressure-assisted nozzle is selected as the injector, as such nozzle is commonly used in industry.

  3. Objectives To perform experimental study of spray characteristics generated by pressure assisted swirl nozzle NS30, which forms hollow spray with cone angle equal to 30 deg. Nozzle diameter is equal to 0.25mm. To investigate the effect of liquid properties on the spray characteristics: A mix of 15wt% ethanol and 85wt % water. Pure waterThe operating pressure is 50 psi (3.4atmg), volume flow rate is 0.34 cm3/s. Following spray parameters were measured by TSI PDPA system: Droplet diameters, D10 and D32=SMD, Droplet axial velocity distribution Relative axial volume flux distribution

  4. Experimental Setup Fuel = Kerosene Mass flow rate 1 g/s. Spray Nozzle diameter: 0.4mm Oxidant = Air, Mass flow rate 29g/s. • CFD Study

  5. Comparison Of Results [CFD Vs Experimental] Gas Temperature Profile Along Tube Axis

  6. X Main Flow Direction Transmitting Optics (Beams are in the x-z plane) Y j Z Receiving Apertures The Dual PDA Planar PDA Conventional PDA Spherical droplets

  7. Refracted rays by a transparent droplet(first order refraction only). f

  8. Simulations: interference pattern using 1st order refraction

  9. Simulations: interference pattern using 1st order refraction The signals of the two detectors will show a phase difference θ. The phase difference θ (in degrees) will be related to their lateral separation according to

  10. COMMERCIAL LDV/PDPA system

  11. Refraction, p=1 Rainbow Angle p= 2 Detailed description of light scattering by a droplet Incident Illumination Reflection p=0

  12. Scattering angle: 50° 60 Air bubble in water 40 Reflection 20 Phase (deg) 0 5 10 15 20 25 30 -20 Water droplet in air Refraction -40 -60 Diameter (micron) A linear relationship between measured phase difference and particle diameter only exists, if the detector is positioned such that one light scattering mode dominates. Phase - diameter linearity • Simultaneous detection of different scattering modes of comparable intensity leads to non-linearities in the phase-diameter relationship.

  13. General features of PDA Simultaneous measurement of velocity (up to 3 components) and size of spherical particles as well as mass flux, concentration etc. Dp = 1 – 500 microns First publication by Durst and Zaré in 1975 First commercial instrument in 1984 Non-intrusive measurement (optical technique), on-line and in-situ Absolute measurement technique (no calibration required) High accuracy: Velocity +/- 0.5 %, size +/- 5% Very high spatial resolution (small measurement volume)

  14. TEST RESULTSEthanol-water spray at liquid pressure of 50psi. Diameter and axial velocity histograms at spray center, Number measurements = 20.000

  15. Radial distributions of D10 for different distances from nozzle • (mixture 85/15wt% )

  16. Radial distributions of D32 for different distances from nozzle • (mixture 85/15wt% )

  17. Radial distributions of the average axial droplets velocities for different distances from nozzle(mixture 85/15wt% )

  18. ) • Radial distributions of theliquid volumeflux for different distances • from the nozzle(mixture 85/15wt% )

  19. Comparison of the radial distributions of D10 for water and water-ethanol (85/15wt% ) sprays.

  20. Comparison of the radial distributions ofD32for water and water-ethanol(85/15wt% )sprays

  21. Summary and conclusions: Spray measurements of pressure swirl atomizer for water and water-ethanol 85/15 wt% mixture using LDV/PDPA system were carried out The following results were obtained: Spray angle for water is slightly higher than mixture due to lower water viscosity. SMD values of water spray slightly lower than that of the mixture. The reason is that water viscosity is lower than that of the mixture and this reduces SMD. From the other point of view, water surface tension is higher than that of the mixture and this increases SMD. The results are in a good agreement with known empirical relationships. Empirical correlations for standard atomizers fail to predict accurately the size of the present atomizer

  22. Thank you

  23.  360° Detector 1 1-3 1-2 Detector 3 1-3  1-2 Detector 2 d 0 dmeas. dmax Overcoming the 2 ambiguity Increasing the measurable size range Maintaining a high measurement resolution 3-detector set-up

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