Newsletter #18


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 # 18 - October, 1994


The ILASS-94 Annual Meeting was distinguished with significant attributes. First, the meeting itself was impressively organized by our local host, Professor John Kramlich at the University of Washington. Secondly, the addition of two tutorials on the opening evening were well attended and well received. The two topics (spray modeling and mass flux measurements) provided for spirited discussion and the development of needed insights. Thirdly, the three invited speakers hit the target in providing perspectives in the spray application areas of materials, paints, and materials. Each was effective in stimulating discussion and thinking in applications with which many of us have had little or no prior experience. Fourth, the newly structured committees in materials and agricultural sprays met to set dynamic goals for future meetings, in general, and technical exchange in particular. Fifth, the tours at Boeing (the widebody flight lines including the 747, 767, and new 777; and the icing tunnel facility) were remarkable examples of engineering technologies that added a lasting impression to an already memorable week.

The Seattle meeting set the stage for the upcoming ILASS-95 Annual Meeting in Troy Michigan where we will have the opportunity to benefit again by the stimulating format of the ILASS meetings, and to benefit by the hospitality of the automotive industry. The dates to note on your calendar are 21-24 May 1995, and we look forward to seeing you.

We welcome to the ILASS-Americas Board of Directors Greg Smallwood (Canadian National Research Council), Steve Londerville (Coen Company), and Andrew Hewitt (Stewart Agricultural Research Services).

                                                   Scott Samuelsen
                                                   Chair, ILASS-Americas


The Seventh Annual ILASS-Americas Conference was held May 31 - June 3, 1994 at the Red Lion Hotel, Bellevue, Washington. The meeting was a great success with 102 attendees. Three invited papers, forty-two presentation papers, and four poster papers were given on subjects that included: Coatings and Materials, Atomization and Spray Modeling, Performance of Spray Systems, Agricultural Sprays, Instrumentation and Measurement Techniques, Atomization Measurements, and Reciprocating Engine Sprays. Thanks are due to John Kramlich (Local Arrangements Chair), JIm Peters (Papers Chair), and Jill Tolliver and Amanda Horner (Conference Coordinators). Copies of the Book of Abstracts are available at a cost of $75 each from the Secretary.


The Annual Business Meeting of ILASS-Americas was held during the conference luncheon on June 3, 1994 at the Red Lion Hotel, Bellevue, Washington. Chair Samuelsen reported on the health and status of ILASS-Americas as demonstrated by the success of the conference. Treasurer Reitz gave a summary of the minutes from the previous Annual Business Meeting, and reported that the ILASS treasury currently holds assets of $34,600. Both the Minutes and Treasurer's Reports were voted on and approved. It was reported that the Board of Directors had appointed Steve Londerville to fill the remainder of Julian Tishkoff's term on the board, and that the Nominating Committee had advanced the names of Will Bachalo, Greg Smallwood, and Andrew Hewitt to fill vacancies on the board. The list of nominees was approved unanimously. Presentation of the Marshall Award was made to Chris Edwards and Ken Marx for papers presented at the previous conference. The student presenters and invited speakers were recognized and thanked for their contributions to the conference. It was announced that additional student travel support for ICLASS in Rouen was available by contacting Chair Samuelsen, and that the exact dates and location of the next year's conference had yet to be determined.


The Sixth International Conference on Liquid Atomization and Spray Systems, ICLASS-94, was held July 18-22, 1994 at the Palais des Congres in Rouen, France. The technical sessions featured four plenary lectures and 141 papers organized into thirteen sessions. Technical visits were made to the CORIA laboratory in Rouen, SEP (the European propulsion society) in Vernon, and the Bassin des Carenes in Val de Reuil. Copies of the Proceedings may be obtained from Dr. Christophe Dumouchel, Universite de ROUEN, URA 230/CORIA, BP 118-76 134 Mont-Saint-Aignan Cedex, France (e-mail:, phone: 33 35 14 65 60, fax: 33 35 70 83 84).

Atomization and Sprays JOURNAL

The Institute of Scientific Information (ISI) in Philadelphia has decided to include the ILASS Journal, Atomization and Sprays, in Current Contents, which will include indexing and abstracting of journal articles. Inclusion in Current Contents is the first step toward inclusion of the journal articles in Citation Index, also published by ISI. The selection of journals for inclusion in Current Contents and the Citation Index is dependent upon the quality of the articles and the regularity of publication.


The International Council of ILASS met at ICLASS-94 in Rouen on Tuesday, July 19, 1994. Discussions were held on the role of the International Council and its relationship with national and regional ILASS groups. A committee was appointed to write a constitution for the International Council. ILASS-Europe did not have a candidate for Chair of the International Council. ILASS-Asia nominated Professor Hiroyasu, who was elected Chair for three years. The Council agreed that the next ICLASS Conference would be held in Seoul, Korea in 1997--probably in August. Recommendations were made to periodically issue an ILASS-International Newsletter and to encourage interaction between national and regional ILASS groups.

TECHNICAL COMMITTEE REPORTS (Reports from the Technical Committee meetings and Tutorials held at the Seattle Conference. Additional reports will appear in the next issue of the Newsletter.) Automobile/Diesel Technical Committee Meeting Chair: Rolf Reitz

The Automobile/Diesel Technical Committee of ILASS-Americas met with 13 attendees.

Government regulations are providing incentives for increased emissions research in diesel engines. Methods were discussed for increasing the participation of engine manufacturers in ILASS. It was suggested that the Poster Session should be given more prominence at the meetings, and that industrial representatives should be encouraged to present posters and exhibits. It was also suggested that the technical committee should be expanded to include both diesel and S.I. engines due to the importance of fuel preparation in port fuel injected engines.

The committee spent much of the remaining time discussing technical issues. It was decided that methods for visualizing and predicting the fuel-air mixing process are fruitful areas for future research in both spark-ignited and diesel engines. The fact that engine sprays are transient and turbulent introduces special considerations. Other factors that influence the fuel-air distribution that were discussed included: nozzle atomization (and the influence of nozzle internal flow details on liquid breakup); the role of supercritical drop vaporization phenomena; and spray/wall fuel films. In addition, optimization studies of fuel injection rate-shape and split (multiple) injections were considered to be promising avenues to explore. Further work is needed to assess the influence of these phenomena on engine emissions. Finally, it was decided that comprehensive models for predicting NOx and soot emissions need to be developed and tested under realistic diesel engine conditions.

Spray Measurement Instrumentation Technical Committee

Chair: Scott Samuelsen

Thirty two members participated in the Spray Measurement/Instrumentation Technical Committee Meeting. Some areas of interest given by those present were:

  1. Paint sprays
  2. Chemical sprays
  3. Icing cloud tests for aircraft
  4. Gas turbine combustion
  5. Fuel injection for automobile engines
  6. Spray nozzle design
  7. Rocket engine propulsion
  8. Instrument design & manufacturing

The main purpose of this committee is for members to "brainstorm" ideas for technical development of spray measurement instrumentation, and to provide direction to both the user and manufacturer communities. In order to adequately satisfy the needs and interests of those working in the field of spray measurement, a balance between academia and industrial representation is desirable.

The committee reviewed the list of "living issues." Action was taken on two areas by establishing the following study committees: Statistical Significance Committee-Will Bachalo, Chris Edwards, Al Orr, and Vince McDonell (Chair), and Characterization Committee-Engin Arik, Ken Giles, Jan Kennedy, and Chien Pei Mao (Chair). The committees were charged to report back at the ILASS-95 meeting with recommendations toward the goal of establishing meaningful protocols.

Three major issues for future consideration and study were introduced.

  1. Experimental and modeler interaction improvement. A data format, which has been established by an AFOSR committee, should be considered to standardize the documentation and archiving of data.
  2. High-pressure measurements should be added to the list of protocol development.
  3. A definition of what constitutes a dense spray would be valuable. One possible definition would be to establish a ratio between the droplet spacing and diameter. A ratio of 10 would be considered dense.

New measurement methods and requirements were discussed. Areas of interest included:

  1. Droplet temperature measurement. Some work is being done by Aerometrics in this area. A discussion will be prepared for the next meeting.
  2. Development of a commercially available "Spray Patternator." Two such devices may already be available from the University of Vienna and Lucas Company in the U.K. A discussion will be prepared for the next meeting.

The following topics were proposed for the 1995 tutorials:

  1. "Data Base Archiving"
  2. "Basic Industry Discussion on Particle Measurements"
  3. "PDI Mass Flux Measurements Follow-Up"

Industrial Technical Committee

Chair: C. Lipp

The industrial committee members represented industrial users of sprays (coatings, chemical manufacturers, Pulp and Paper as examples), manufacturers of industrial nozzles and University researchers. There were 17 attendees. The consensus was that the tutorials were an excellent addition to the program and should be continued. A discussion of a very broad range of technical topics of interest resulted in three significant areas of common interest to the technical committee and to ILASS:

  1. Non-Newtonian behavior of emulsion/particulate containing liquids. Paints as the prime example.
  2. Sprays where drop size is not a key measure of system performance, impinging sprays used for cleaning or cooling.
  3. Environmental impact of non-combustion sprays. Examples are spray drying, second generation flue gas desulfurization and toxicology. Environmental regulations have driven major changes in combustion systems involving sprays and the changes in non-combustion systems are underway.

The Chemical Engineering community is not being reached to a sufficient degree. One of the common interests by members from industry is to hear about the non-proprietary aspects of another industrial use which may be of high value in another area.

The following tutorial topic was suggested for next year's meeting: PDPA Volume Flux. It was suggested to allocate at least 2/3 of the time for discussions. For the program, the following suggestions were made:

  1. Spray drying-The atomization and spray community has advanced since the last major involvement at ILASS several years ago. An informal task group is working to identify an appropriate person to give an invited paper.
  2. Industrial sprays session-Include to encourage industrial participation.

Joint Spray Modeling/Spray Combustion Technical Committee Meeting

Chairs: Josette Bellan and Chris Edwards

A joint meeting of the Spray Modeling and Spray Combustion Technical Committees was conducted on Wednesday, June 1, 1994. There were 20 attendees. The reason that a joint meeting was held was that it was felt by each group that many of the issues to be discussed were held in common and that each group would benefit by participation of the other.

The agenda of the meeting included three items: discussion of the conference, development of a list of issues, and discussion of selected issues from that list. It was pointed out that most of the issues from the modeling side had already been covered in the previous evening's tutorial workshop.

Regarding the structure of the conference, it was generally felt that there should be only one tutorial at a time. Most attendees were disappointed that a choice had to be made between the two topics. It was also felt that if time were an issue, it would be preferable to have fewer Technical Committee meetings in favor of single-session tutorials.

Issues for discussion in spray combustion began with the 1990 revisions to the Clean Air Act, in particular, the new air toxics provisions. It was pointed out that the emission levels required by the legislation are divorced from any knowledge of what levels are achievable. This led to a discussion of how chemical kinetics could better be incorporated in spray combustion modeling. It was suggested that the treatment of chemical kinetics in spray models should closely follow the state-of-the-art in gas-phase modeling. But it was also recognized that spray combustion adds it own problems because of important physics that is unique to sprays.

An example of physics which is unique to sprays was cited as the dominant issue in rocket (and possibly diesel) combustion: supercritical reactive flow modeling. Development of models based on non-traditional viewpoints was suggested as important, as was finding ways to provide validation of proposed models.

Shifting topics to gasoline engine atomization and combustion, it was stated that the objective of the auto companies is two part: (1) to establish the relationship between spray characterization and atomizer design, and (2) to establish the relationship between spray characteristics and engine output. It was recognized that models are still needed for many subprocesses, including gasoline atomization, liquid wall wetting, etc. It was also pointed out that not only are emissions an important factor in assessing gasoline spray injector performance, but so too is reproducibility-an aspect often taken for granted.

A general consensus of the group was that more collaboration is needed between modelers and experimentalists. Often models can, and do, lead the experiments into new directions, but the results of these models can only be used with certainty once proper experimental validation is obtained.

Spray Modeling Tutorial - Future Trends/Expectations

The Spray Modeling Tutorial was held at the Red Lion Hotel, Bellevue, Washington, at 7 PM on Tuesday, May 31, 1994. The moderator was Rolf Reitz, and the invited panelists were S. Drennan (representing industry), J. Bellan (representing government), and N. Ashgriz and S. Heister (representing universities). The first hour was spent in presentations from the panelists, and the second hour consisted of a lively question and answer session involving all attendees. Thirty were in attendance.

Spray modeling is being used increasingly by industries to help improve product design and performance. The increased use reflects increased confidence in the accuracy of CFD predictions, the increased availability of CFD codes that include spray models, and the availability of high performance workstations and supercomputers. S. Drennan described successful uses of a commercially available CFD code in his company. He noted that some customers are now requiring CFD analysis of combustion system designs prior to hardware testing. He also noted the need for improved submodels for processes such as atomization, combustion, char burnout, and emissions formation. J. Bellan emphasized the importance of accounting for differences between the dense sprays encountered in practical applications and the ideal dilute sprays that are typically considered in spray models. N. Ashgriz and S. Heister described promising new techniques for predicting the outcome of the atomization process, including Volume of Fluid and Boundary Element methods.

The need for validation data for assessing the accuracy of CFD and atomization model predictions was stressed during the discussion period that followed the presentations by the panelists. Much discussion dealt with methods to bridge the gap between detailed atomization models and their implementation in CFD codes. It was decided that atomization models should be developed that can address the relationship between the nozzle internal flow details and the spray drop size distribution. To be useful, atomization models should also be able to account for the effects of flow turbulence and nozzle cavitation on the atomization process. Finally, the need for accurate submodels for combustion and emissions with detailed chemistry and multicomponent fuel mixtures was discussed.