Newsletter #22


ILASS - Americas

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

Editor: Prof. Chris F. Edwards
Secretary, ILASS-Americas
Mechanical Engineering Dept.
Stanford University
Stanford, CA 94305-3032

Newsletter # 22

(Reports from the Technical Committee meetings held at the San Francisco Conference.)

Propulsion (Gas Turbine and Rockets)
Chair: Ted Koblish, TRK Combustion.
Co-Chair: Curt Scheuerman, Parker Hannifin Corp.
Co-Chair: Doug Talley, USAF Phillips Lab.

As announced at the 1995 ILASS meeting, the name of the committee was changed to include the additional activity represented by the Rocket Propulsion members of the technical committee.

A total of 17 members were in attendance at this meeting as compared to 20 in the 1995 meeting at Troy, Michigan. This accounts for a total of 26 interested members in the ILASS Gas Turbine & Rocket Propulsion Technical Committee. A notable attendee was Vladimir Bazarov, Moscow State Aviation Institute, who expressed an interest in all the fuel injector technologies! Eleven attendees 53% (1995, 55%) represented Industry, five attendees, 29% (1995, 30%) represented Academia, while three attendees. 18% (1995, 15%) represented Government Agencies. Based on the responses to the questionnaire filled by each attendee, the following profile of interest was identified as charter technical subjects for the Gas Turbine & Rocket Propulsion Technical Committee of ILASS:

I. 	Primary Application	- Gas Turbine/Multi Fuels. 	27% (1995, 25%)
	Interest	- Gas Turbine-Low Emissions	30% (36%)
		- Rockets	33% (25%)
		- Other	10% (14%)

II.	Fuel Injector	- Pressure Atomization	18% (16%)
	Concept Interest	- Air Assist Pressure	13.3% (12%)
		- Air Blast	13.3% (13%)
		- Air Shear	10.8% (13%)
		- Effervescent	13.3% (13%)
		- Co-Jet	14.3% (16%)
		- Interacting jets	12% (13%)
		- Other	5% (4%)

III.	Information	- Experimental Data	35% (46%)
	Desired	- Empirical Correlations	32.5% (32.5%)
		- Theoretical Predictions	32.5% (32%)

IV.	Members willing to submit a technical abstract for the 1997 ILASS Meeting	71% (75%)


  • Initiate quarterly newsletter to all technical committee members. This may or may not be extended to a contact in the area Propulsion industries.
  • Establish Roster membership list and mail to all members registered by the 95/96 questionnaire of the Gas Turbine & Rocket Propulsion Committee.
  • Establish an "E" mail listing to provide membership communication capability for technical information exchange.
  • Establish World Wide Web site at U.C. Irvine as an electronic pilot program for members of the Propulsion Committee. Key people in this effort are Vince McDonell of U.C. Irvine and Peter Buca of Parker Hannifin, who will coordinate the required effort to initiate the program.
  • Increased activity in Scram-jet and Ram-jet programs has added a new category of membership interest! Robert Jensen of Rocketdyne volunteered to oversee this activity for the Committee.
  • Committee Chairmen will cover and promote Committee interests to Industry centers in their sections of the country:
    	Curt Scheuerman	-	Midwest/East
    	Doug Talley	-	West/Northwest
    	Ted Koblish	-	Southeast/Southwest

    Industrial Sprays
    Chair: Chuck Lipp, Dow Chemical
    Co-Chair: Paul Sojka, Purdue University

    The Industrial technical committee members represented users of sprays (Coatings, Chemical Manufactures, consumer products, Nozzle manufacturers, and University researchers. Environmental regulatory efforts continue to be drivers of change in industrial applications

    A better understanding of fundamental liquid fluid property effect on spray performance is needed. Non-Newtonian liquid characteristics are of the most industrial interest. The discussion included methods to transition from technology to science as well as increasing the level of science in this area. It was thought that review papers might be a step along this path first dealing with Newtonian liquid viscosity.

    Environmental regulation changes are forcing product reformation that changes spray performance. Drop size as well as other spray attributes (evaporation rates, entrainment, drop size distribution, spray pattern, drop velocity distribution).

    The Chemical Engineering community (spray drying) is not well represented and additional efforts would be fruitful.

    Very fruitful and enlighten discussion can focus on common area of base technology (everybody needs to practice well) and thus avoiding the competitive technology.

    Boiler/Furnace/Incinerator Sprays
    Chair: Steve Londerville
    Co-chair: Chris Edwards

    A meeting of the Boiler/Furnace technical committee was held during ILASS-96 in San Francisco. Present at the meeting were:

    John Hurley, Combustion Components
    Cary Presser, NIST
    Vladimir Lifshits, Coen Company
    Steve Londerville, Coen Company
    Chris Edwards, Stanford University

    The majority of our discussion centered around how to augment involvement of the boiler and furnace community in ILASS. Steve Londerville suggested tapping into the American Flame Research Committee, the ASME fuels group, and others. It was generally agreed that ILASS information is sent to too narrow an audience and that the ILASS-Americas mailing list should be expanded. John Hurley offered that the location was important and that seeing one or two key papers in the program can make the difference. In his case, it was the Coen paper that had peaked his interest to attend. Use of a key speaker in the area of boilers/furnace as a drawing card was discussed, as was the idea of soliciting papers for a special session. John also supplied a list of key industrial contacts with interests in sprays.

    A list of applications, issues and interests was also drawn up and discussed, as listed below.
    Air Heaters
    Spray Dryers
    Gas Generators
    Gas Reheat

    Inside Mix
       Nat. Gas
    External Mix
    Air Blast
    Tip Mix
    Rotary Cup

    #6 Residual
    #2 Fuel Oil
    Used Motor Oil

    Size: 60,000 Btu/hr
       to 500,000,000 Btu/hr
    Air Temp & O2
    Design Type
    Flame Shape
    Heat Flux
       particulate, NOx
       opacity, CO2/H2O
       SMD Distributions
       atomizing gas quantity
       predicting perf.

    Compatutions and Modeling
    Chair: Josette Bellan, Jet propulsion Laboratory
    Co-Chair: Nader Rizk, Allison

    The meeting convened at 5:45PM with 12 participants; the co-chair, Dr. Nader Rizk could not attend due to unforeseen circumstances.

    Following an Agenda previously distributed to members of the Committee, the discussions started regarding the state of the art predictions for drop size distributions from injectors. It was pointed out that predictive models do not exist for a variety of injectors both for primary and secondary atomization. This is due to the lack of definitive measurements showing the phenomena occurring during atomization. If such information were available, it was pointed out that DNS calculations of sheet breakup could be carried out. Other techniques could also be used, such as LES and surface tracking. The questions of geometry and the coupling with the outer flow field (i.e. that not immediately adjacent to the atomizing jet) were seen as crucial. Industrial participants pointed out that there is an increasing emphasis in industry to use CFD codes to predict accurate quantities; currently, however, all that can be expected from CFD atomization codes is qualitative predictions as a function of parameter variation.

    The issue of interaction of drops with turbulence and the prediction of unsteadiness during combustion were also discussed in the context of the industrial need to control processes in gas turbine engines. The need to predict the drop interaction with different turbulent scales was viewed as crucial when combustion is present because chemistry occurs at very small scales. The Eulerian-Lagrangian technique involving solving the flow equations in an Eulerian frame and following the drops on their trajectories was seen appropriate only for laminar, dilute situations. This is because if such a technique is used to represent groups of drops with a single representative drop, the volume of the group must remain much smaller than the Eulerian computational cell. If this requirement is not satisfied, the model biases the calculation of the flow (due to coupling between representative drops and flow) by putting too much mass, momentum and energy on each trajectory of representative drops.

    The meeting ended at 7:15PM without covering all points of the Agenda.

    Chair: Scott Samuelsen, UCI
    Co-Chair: Chien-Pei Mao, Delavan

    1. Introductions - an attendee list was generated
    2. Review of Minutes - minutes from the 1995 meeting were circulated, reviewed, and approved.
    3. Objectives - the objectives of both the committee and the meeting were reviewed
    4. Standing Business:

    Review List of "Living Issues" - the committee reviewed the list of "living issues" and suggested the following additions:

  • large dynamic range measurements (Michael Benjamin, Parker-Hannifin)
  • protocol for defining the envelope for accurate measurements; identify limitations of instrument response (Will Bachalo, Aerometrics)
  • repeatability (Cary Presser, NIST)

    Review List of "Living Measurement Methods" - the committee reviewed the list of "living measurement methods" and suggested the following additions:

  • PDI (phase-Doppler interferometer) measurements of white paint droplets; droplets containing particles in suspension (Richard Baird, Boeing)
  • film thickness (Greg Smallwood, NRC); apparently Nanometrics makes an instrument to measure film thickness (Richard Baird, Boeing)
  • spray properties in a multi-point injection system; influence of neighboring sprays in a multiple nozzle system (Pete Buca, Parker-Hannifin)
  • index of refraction independent of temperature (Alessandro Gomez, Yale)
  • droplet and phase properties under critical and near-critical conditions (Michelle Zaller, NASA Lewis)
  • extend planar measurements to volumetric measurements (Cary Presser, NIST)

    Report of the Ad Hoc Committees:
    (i) Statistics (Vince McDonnell, UCI)

  • tutorial topic suggested in 1995 meeting (Statistics from Single Particle Counters) was presented in a workshop on Sunday evening; the content from these presentations will be included in the minutes
  • report from Al Orr (Graco) on ensemble measurements
  • imaging instruments are a third class to be considered, in addition to PDI and diffraction/ensemble; Chuck Lipp (Dow Chemical) volunteered to lead this effort
    (ii) Spray Characterization (Chien-Pei Mao, Delavan)
  • a straw-man proposal for PDI operation protocols was presented
  • volunteers to review the straw-man proposal are Will Bachalo (Aerometrics), Cliff Weissman (Dantec), and Thom McCracken (NRC) A vigorous discussion followed:
  • calibration with monodisperse drops was far from measured drop sizes (Michelle Zaller, NASA Lewis)
  • Volume flux was correct (Chien-Pei Mao, Delavan)
  • why not calibrate with small droplets, in the range of expected measurement sizes? (Vince McDonnell, UCI)
  • need to use large droplets to calibrate full range (Chien-Pei Mao, Delavan)
  • comments on calibrations are potentially dangerous, as PDIs are calibrated at the factory and should not be tampered with; use of large droplets can cause phase response rollover, resulting in a new slope and incorrect calibration for small droplets; users should read the instrument manual and contact manufacturer for assistance (Will Bachalo, Aerometrics)
  • leaving calibration at factory settings doesn't solve the problem for those who want to measure large drops (SMD = 200 mm) (Chien-Pei Mao, Delavan)
  • protocol should indicate that calibration should reflect range of expected droplet sizes, and should include 3 points across the range to verify linearity (Tom Bassett, BETE Fog Nozzle)
  • a technote will be made available for re-calibration (Will Bachalo, Aerometrics)
  • potential problem with PMT voltage and detector spacing (Michelle Zaller, NASA Lewis)
  • optimum voltage is in the range 350-400V (also found by Vince McDonnell, UCI and Chien-Pei Mao, Delavan); need for calibration should be preceded by a call to the manufacturer (Will Bachalo, Aerometrics)
  • standard practice has proven to be repeatable (Chien-Pei Mao, Delavan)
  • look for other sources of error before changing internal setup of instrument (Cary Presser, NIST)
  • one instrument does not have an option for changing detector spacing, only the high voltage can be adjusted; protocols must be generic to all PDI instruments (Cliff Weissman, Dantec); concur (Will Bachalo, Aerometrics)
  • these instruments will never be turnkey; to make them so would be dangerous (Jim Drallmaier, University of Missouri-Rolla)
  • someone at NASA Lewis has developed a PDI protocol (Michelle Zaller, NASA Lewis)
  • Feedback to manufacturers - None (see above)
  • New business - possible use of WWW to disseminate information and to receive feedback (Scott Samuelsen, UCI)
  • . Adjourn