Newsletter #19


ILASS - Americas

Institute for Liquid Atomization and Spray Systems - North and South America.

Editor: Dr. Chris F. Edwards
Secretary, ILASS-Americas
Combustion Applications, MS 9053
Sandia National Laboratories
Livermore, CA 94551-0969

Newsletter # 19 - April, 1995


The ILASS-95 Annual Meeting will be held in the automotive capital of the world. The site is a short 40-minute drive from the Detroit Metro Airport:

                 Somerset Inn
                 Troy, Michigan
                 May 21-24, 1995

The meeting is hosted by the General Motors Research and Development Center, and the schedule includes a tour of the GM Research Laboratory in Warren Michigan.

Dr. Josette Bellan has organized an impressive meeting with an increase in papers presented of 38% over any previous ILASS-Americas Annual Meeting. Make sure to look at the meeting announcement for details. We will, for the first time, experiment with double sessions for one day of the meeting.

Two tutorials will be held on Sunday night, building on the very successful "tradition" started last year. The topics have been selected to "continue" on the fundamental themes raised at the Seattle venue: Modeling and Instrumentation. This is a special opportunity to spend extended time in a "town-hall" format, raise questions, contribute with your own experiences, and generally become familiar with the critical issues that face these two areas of broad concern and interest in atomization and sprays.

Another tradition of the ILASS-Annual Meeting, the invited speakers, is being maintained with an exciting menu of topics that include: "The Non-Aerosol Haircare Business," "Research and Development Needs in Paints and Spray Coatings," and "Automotive Industry Research Directions on Fuel/Air Mixture Preparation for Emission Control."

We look forward to seeing you in Michigan in May.

                                                   Scott Samuelsen
                                                   Chair, ILASS-Americas

Atomization and Sprays JOURNAL

Nineteen ninety-four was the first year that six issues of the ILASS journal Atomization and Sprays were published. Thirty-six papers were published: United States - 11; Israel 4; Japan 3; United Kingdom 2; Korea 2; and one each from China, Germany, Denmark, Spain, Taiwan, India, and France.

Authors who have made presentations at ILASS-Americas, Europe and Japan, and ICLASS conferences, are encouraged to submit extended papers, suitable for publication in an archival journal, to the editor of Atomization and Sprays. Members of ILASS Americas who do not attend our annual conferences should send their annual personal subscriptions to Begell House, to assure continuity in mailing.


The third Symposium on Atomization, ILASS-Japan, was held December 21-22, 1994 at Keio University, Hiyoshi campus in Yokohama Japan. The meeting was a great success with 204 attendees. Forty-five presentation papers were given on subjects that included: Measurement, Atomization Modeling, Diesel Sprays, Atomization Mechanisms, Aerosols, Particle Production, and Evaporation. The ILASS-Japan Annual Meeting was held on the same day and Professor Hiroyuki Hashimoto was elected as the new Chair of ILASS-Japan.

(Reports from the Technical Committee meetings and Tutorials held at the Seattle Conference.

PDI Mass Flux Tutorial
Moderator:	Jan Kennedy
Panelists:	W. D. Bachalo, L. G. Dodge, A. A. Naqwi, C. Tropea

Fifty people attended the first ILASS-AMERICAS tutorial workshop on Phase Doppler: Mass Flux Measurement. They enjoyed the lively, interesting, and educational discussions on the capabilities of the phase Doppler systems, as well as discovered the many problems that can be encountered in making measurements in dense sprays. Lee Dodge, a user of the phase Doppler instrument, initiated the discussion with a review of the successful application of the instrument to characterizing the droplet sizes and mass flux measurements of dilute sprays at low velocities. However, at higher mass flow rates and high air pressure drops across an air-assist injector or higher droplet velocities, a significant discrepancy in the SMD was measured between the laser-diffraction and phase Doppler systems and the integrated mass flow rate from the phase Doppler instrument was significantly lower than the input mass flow rate.

Amir Naqwi, representing TSI, Inc. and their Adaptive Phase Doppler Velocimeter (APV), spoke next and discussed the capabilities of their instrument to measure the droplet refractive index and submicron drop sizes. The influence of multiple scattering and droplet trajectory ambiguity as related to mass flux measurements in dense spray were also discussed.

Will Bachalo, representing Aerometrics, Inc. and their Phase-Doppler Particle Analyzer (PDPA), spoke next and addressed the mass flux measurements issues as related to angularity in the droplet trajectory, reduced signal-to-noise ratio, nonuniform illumination of the drops, and definition of the sample volume.

Cam Tropea, representing Dantec Measurement Technology and their Laser Doppler Anemometer (LDA), was the final speaker and described a phase Doppler arrangement that eliminates the gaussian beam defect or trajectory effect, considered important for large particles. Cam also reviewed the many problems that can be encountered in dense sprays such as slit aperture in front of the photodetectors.

In summary, all of the speakers mentioned similar problems associated with measuring size and mass flux in dense sprays. Whether the systems can successfully accomplish the task was not determined, but where the problems arise could be determined using C. F. Edwards and K. D. Marx's analysis from Sandia National Laboratories and presented at the 6th ILASS-AMERICAS meeting.

Physics of Atomization

Chair: Norman Chigier

Twenty-three participants discussed their particular interests in the physics of atomization. The main interest was in hydrodynamic instabilities and growth of waves and disturbances on liquid jet surfaces. Special interest was shown in acoustic perturbations and interaction between acoustic waves and capillary waves for damping and increasing of wave amplitudes. Interest was expressed in obtaining more information on Kelvin Helmholz instabilities and Marangoni effects. Surfactants have been shown to result in dynamic surface tension, with resultant effects on drop size. Formation of bubbles in effervescent atomizers, generates ligaments inside the atomizer and results in improved atomization. Compressible gas dynamics, sonic and supersonic gas flows, and flashing in two-phase flows need further examination.

For hair sprays, normal and isopropane are being used in place of solvents (VOC), using swirl atomizers. Users of hair sprays can detect the difference between 40 and 50 micron sprays. It was recommended that a document be written focusing on the Physics of Atomization Technical Committee.

Gas Turbine

Chair: Jan Kennedy

The attendees included 58% from industry, 25% from universities and 17% from government. The topics that were discussed included comments on the ILASS meeting, papers, tutorials, critical issues, value of ILASS, and selection of a new chairman and vice-chairman.

Everyone was pleased with the ILASS 7th meeting and the opportunity to meet others in the atomization and spray fields in the different forums, i.e. papers, tutorials, technical committees, breaks, etc. Concern was expressed by several attendees about the small number of gas turbine papers. The group was commissioned to contact the gas turbine people to generate more attendance and oral and poster papers for the next meeting. To assist this effort, a list of gas turbine related contacts will be assembled. Both tutorials were enjoyed and the discussions valued. More time for discussions was requested with three speakers as a limit. Future tutorial topics suggested include:

  1. The critical issues facing the gas turbine or atomization community
  2. The value of ILASS
  3. Modeling - application or validation
  4. Phase-Doppler - data presentation or interpretation of understanding the physics
  5. Patternation - including field imaging, sheet illumination, intrusive and non- intrusive systems, planar imaging, TV imaging
  6. How can we simply measure sprays for the beginners
  7. What is the injector design philosophy, i.e. flow visualization of air flow, patternation, LV, PDPA, etc.
  8. Supercritical atomization
  9. What do we want to measure in sprays?
  10. How do we measure the liquid/gas ratio in sprays?
  11. How do we use the ILASS papers or posters or abstract?
  12. How do we scale up or down the test conditions for gas turbines?

Due to his responsibilities as Vice-Chairman of ILASS-AMERICAS, Jan Kennedy relinquished his chairmanship of this technical committee and Ted Koblish and Curt Scheuerman volunteered to be Chairman and Vice-Chairman, respectively.

Agricultural Sprays

Chair: Andrew Hewitt

The ILASS Agricultural Sprays Committee met on June 2, 1994 during the ILASS-Americas-94 7th Annual Conference on Liquid Atomization and Spray Systems. Several new members were in attendance, a reflection of the steady growth of this relatively new ILASS-Americas committee. Andrew Hewitt (Stewart Ag./Spray Drift Task Force) opened the meeting with a general discussion of issues the committee might consider addressing at that time. Specifically, he asked whether there was any interest in looking at airborne spray sampling techniques; however there appeared to be no interest at that time.

The progress of the inter-laboratory round-robin study of laser particle size analyzers was discussed. Rudy Schick (Spraying Systems) agreed to provide a fixed liquid delivery system with pressure gauge close to the nozzle, to ensure the same set-up at every participating laboratory. Hewitt pointed out that the round-robin is now underway, with several laboratories in the U.S.A. and Australia having already conducted the tests with the glass beads and calibration reticles.

Hewitt commented that he would be attending the ICLASS-94 conference in France: Norman Akesson (University of California, Davis) noted that he would also be attendance. Hewitt chaired an informal lunch meeting at that conference to involve international representatives of agricultural spray research and application facilities in the activities of the ILASS-Americas Agricultural Sprays Committee. The meeting and ICLASS conference were very successful. Several European groups showed an active interest in the committee. Some European researchers suggested that a database be compiled from all available data on droplet size spectra produced by agricultural nozzles and atomizers; however no volunteers were forthcoming to undertake that immense task. Hewitt will write to the members of the Agricultural Sprays Committee to ascertain whether there is broad interest in the idea of the development of an agricultural atomization database, and whether the committee members and other groups can provide data for inclusion in such a database.

The committee will meet again at the ILASS-Americas conference in Troy, Michigan, May 21-24, 1995.