[American Institute of Aeronautics and Astronautics 42nd AIAA Aerospace Sciences Meeting and Exhibit - Reno, Nevada ()] 42nd AIAA Aerospace Sciences Meeting and Exhibit - Effect of

American Institute of Aeronautics and Astronautics

1

EFFECT OF OSCILLATING EXCITATION ON A METHANE-AIR DIFFUSION JET FLAME

Masahiro ISHIZAWA1, Masahisa SHINODA2, Hiroshi YAMASHITA3,

Haruo KATAGIRI4, Kuniyuki KITAGAWA5 and Ashwani K. GUPTA6

1. Department of Energy Engineering and Science, Nagoya University

Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan

2. Research Center for Advanced Energy Conversion, Nagoya University


3. Department of Mechano-Informatics and Systems, Nagoya University






6. Department of Mechanical Engineering, University of Maryland

College Park, MD 20742, U.S.A.

Abstract

Experimental observation and detailed numerical

analysis of a diffusion jet flame with an oscillating fuel

flow were performed to investigate the effect of forced

oscillations on the flame. The Reynolds number, Re, and

the Strouhal number, St, were chosen as non-dimensional

parameters to characterize the flame phenomenon. For a

relatively low Reynolds number, the obvious change in

flame shape due to the oscillating excitation was observed

by comparing the two cases of (Re, St) = (151, 0) and (151,

0.42). In numerical analysis, the changes in instantaneous

two-dimensional (2-D) distributions of mass faction of fuel,

temperature, vorticity and heat release rate in the flame

were examined in detail at a higher Reynolds number.

Quantitative comparison of the temporally- and

spatially-averaged heat release rates with and without

oscillations at (Re, St) = (2300, 0) and (2300, 0.0076)

showed that the oscillation enhanced the heat release rate

by about 20 % as compared to the non-oscillation case.

Introduction

The presence of vortices or eddies in turbulent flames

provide an important role on enhanced mixing and

chemical reaction between the fuel and oxidizer. Recently,

some researchers have reported that the acoustic excitation

technique of vortices in the flames provides a means to

control the flame characteristics. For example, Lovett et al.

1. Corresponding author, Graduate Student, Phone: +81-52-789-3913,

Fax: +81-52-789-3910, E-mail: [email protected]

2. Researcher on loan from Nagoya Industrial Science Research

Institute

3. Professor

4. Professor

5. Member AIAA, Professor

6. Fellow AIAA, Professor

42nd AIAA Aerospace Sciences Meeting and Exhibit5 - 8 January 2004, Reno, Nevada

AIAA 2004-815

Copyright © 2004 by Copyright 2004 by the authors. All rights reserved. . Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.


2

[1] showed that the effect of acoustic forcing on flame

lengths. They showed that higher frequency forcing above

10 Hz reduced the overall flame length. Kamiya et al. [2]

obtained similar results using numerical analysis. Their

results showed that the characteristics of flame holding are

improved with periodic velocity oscillations to the fuel jet.

Chao et al. [3-5] showed that acoustic excitation at proper

frequency and amplitude could further enhance the

entrainment effect, leading to NOx reduction and

stabilization of lift-off flames. Hishida et al. [6] examined

the effect of acoustic oscillations on flame shape by

altering the oscillation frequency and jet velocity. Several

investigations, therefore, have been carried out in order to

explore and effectively utilize the role of forced

oscillations on flames. However, most of these studies have

been experimental and qualitative with main focus on

oscillation effects on the flame stability.

In this study, we attempt to provide a quantitative

evaluation for the effect of oscillating excitation on flame

intensity. In particular, the combustion load rate

(temporally- and spatially-averaged heat release rate), CL,

is chosen as one of the important criteria for the flame

intensity. The Reynolds number and the Strouhal number

based on the oscillating cold flow of the fuel,

µρ dVav=Re , (1)

and

avVfd

=St , (2)

are used as the non-dimensional parameters. Here, ρ, Vav, d,

µ and f represent mass density of the fuel [kg/m3], mean

flow velocity of the fuel [m/s], width of the fuel inlet

(diameter of the burner outlet) [m], viscosity of the fuel

[Pa·s] and frequency of the oscillation [1/s], respectively.

In this study, the behavior of oscillating methane-air

diffusion jet flame is observed first using a relatively

simple experimental apparatus. By comparing the two

cases of non-oscillating flame at (Re, St) = (151, 0) and

oscillating flame at (151, 0.42), the influence of forced

oscillation on visible size and shape of the flame is

described qualitatively. In addition, detailed numerical

analysis is performed by solving a set of equations of

reactive gas dynamics. The changes in instantaneous 2-D

distributions of mass faction of fuel, temperature, vorticity

and heat release rate in the flame are examined for the

effect of oscillations. Furthermore, the quantitative effect

of oscillating excitation for given combustion load rate

(CL) are evaluated by comparing the non-oscillating flame

at (Re, St) = (2300, 0) with the oscillating flame at (Re, St)

= (2300, 0.0076).

Experimental Observation

Figure 1 shows the experimental apparatus used in

this study. The coaxial type burner is made of fused silica.

The inner and outer tube diameters are 4 mm and 14 mm,

respectively. The air as oxidizer is fed into the outer tube of

the burner using gas cylinder fitted with a regulator and

flow meter. The methane (CH4) gas is used as the fuel and

is fed into the cone-shape tank from the cylinder through

the regulator and flow meter. The fuel is then oscillated

using a loud speaker (35 W maximum input power, 130

mm in diameter) placed at the bottom of the tank. This

oscillating fuel at a defined frequency is then allowed to

flow through to the inner tube of the burner. The

methane-air diffusion jet flame is formed at the burner exit.

Photographs of the non-oscillating and oscillating flames

are obtained with a digital camera (FUJIFILM A303) at a

shutter speeds of 1/2 - 1/2000 s. The volumetric flow rates

of fuel and air are regulated with the flow meters at 0.5

l/min and 0.1 l/min, respectively. The oscillation

frequencies are set to either 0 Hz and 70 Hz with the

speaker system consisting of a function generator, an audio


3

amplifier and a loud speaker. These conditions of flow

velocity and frequency correspond to (Re, St) = (151, 0)

and (151, 0.42), respectively.

Numerical Analysis

The analytical model and the boundary conditions

applied in the numerical analysis are shown in Fig. 2. The

2-D Cartesian coordinate system, (x, y), is chosen so that x

represent the length in the principal flow direction [m], y

the length in the transverse direction [m], and origin, O, is

set at center of the burner outlet. The thickness of the

burner wall plates separating fuel from air is assumed to be

zero. u and v indicate the x- and y-components of flow

velocity vector [m/s], T the temperature [K], and Yi the

mass fraction of chemical species i [-]. The subscript 0

means the inlet condition of fuel and air at x < 0.

The air inlet conditions are set as follows: u0 = 1.0 m/s,

v0 = 0 m/s, T0 = 300 K, YN2,0 = 0.768 and YO2,0 = 0.232. For

the fuel inlet conditions, u0 = u0(y, t), v0 = 0 m/s, T0 = 300

K and YCH4,0 = 1.0, where t is the time [s]. The flow

velocity distribution at the fuel inlet (the burner outlet),

u0(y, t), is given by assuming the fully developed laminar

flow (the Poiseulle flow) with the temporally periodic

oscillation, i.e., it is given by

( ) ( )12sin15.1,2

0 +

−= ft

dyVtyu av π . (3)

In this study, the following values are chosen: Vav = 39.5

m/s, d = 1.0 mm and f = 0 Hz and 300 Hz. These

conditions correspond to (Re, St) = (2300, 0) and (2300,

0.0076), respectively. The condition of the critical

Reynolds number of Re = 2300 means that the main flow

field can be in a state of turbulence, while the flow field

inside the burner is the fully developed laminar flow

described by Eq. (3).

Using the analytical model shown in Fig. 2, the

numerical calculation is performed by solving the

following five equations of reactive gas dynamics [7, 8],

i.e., the conservation equations of mass, momentum,

energy and chemical species and the state equation:

( ) 0=⋅∇+∂∂ vρρ

t, (4)

( ) ( ) ( )vvvv∇⋅∇+−∇=⋅∇+

∂∂ µρρ p

t, (5)

( ) ( ) ( ) ∑=

−∇⋅∇=⋅∇+∂

∂ N

iii

pp

whc

Tc

TtT

1

11 λρρ v , (6)

( ) ( ) ( ) iiiii wYDY

tY

+∇⋅∇=⋅∇+∂

∂ ρρρ v (7)

and

∑=

=N

i i

i

mYRTp

1ρ , (8)

where, ρ, p, T, Yi, cp, hi, wi, mi, R and v = (u, v) are the mass

density [kg/m3], pressure [Pa], temperature [K], mass

fraction of species i [-], specific heat capacity at constant

pressure [J/kg·K], enthalpy of species i [J/kg], mass

production rate of species i [kg/m3·s], molecular weight of

species i [kg/mol], universal gas constant [J/K·mol] and

flow velocity vector [m/s], respectively. µ, λ and Di

represent the viscosity [Pa·s], thermal conductivity

[J/K·m·s] and mass diffusivity of species i [m2/s],

respectively. For the derivation of a set of Eqs. (4)-(8), the

Soret, Dufor, pressure diffusion and viscous dissipation

effects were ignored. The term of Dp/Dt in the energy

equation was also neglected due to low Mach number

approximation.

For the chemical kinetic mechanism, the overall

one-step irreversible reaction model including five

chemical species such as CH4, O2, CO2, H2O and N2 [9, 10]

is used. The thermodynamic properties of the species are

defined from the CHEMKIN database [11]. The transport

properties are determined from the simplified transport

approximation model [12].

Based on the finite volume method, Eqs. (4)-(7) are


4

made in discrete forms. The QUICK [13] and SIMPLE

methods [14] are used for calculating the convection and

pressure terms. The time integral is made by the Euler’s

fully implicit method with the first order precision using

the time interval of 10 µs. The relaxation at each time step

is made by the SOR method [14] with the relaxation

coefficient of 0.1. The grid size was 303 and 403 in the x-

and y-directions, respectively, and the minimum grid size

was 0.15 mm.

Results and Discussion

Experimental Observation

Figure 3 shows photographs taken with the digital

camera. The upper photograph shows the instantaneous

image of the non-oscillating flame at (Re, St) = (151, 0),

while the bottom photograph shows that for the oscillating

flame at (Re, St) = (151, 0.42). Only one region of normal

luminous flame can be observed for the non-oscillating

case as shown in the upper photograph in Figure 3.

However, two distinct luminous flame regions are formed

along the longitudinal axis of the flame for the oscillating

flame case as shown in the lower photograph in Figure 3.

Furthermore, the length of the oscillating flame is much

larger than the non-oscillating flame. This indicates that

forced oscillation to the fuel flow causes the obvious

change in the flame shape and length. In particular, the area

of the flame zone increases significantly due to excitation

of the flame with the acoustic oscillations.

Numerical analysis

Figures 4, 5, 6 and 7 show the instantaneous 2-D

distributions of the mass faction of fuel, YCH4 [-],

temperature, T [K], vorticity, ω [1/s], and heat release rate,

Q = Σ hiwi [J/m3·s], respectively. In each figure, the upper

and lower diagram correspond to the calculated results for

the non-oscillating flame case at (Re, St) = (2300, 0) and

the oscillating flame case at (2300, 0.0076), respectively.

From both Figs. 4 and 5, the complex patterns of YCH4

and T distributions for the oscillating case of (Re, St) =

(2300, 0.0076) are generated at upstream regions of the

flame in comparison to the non-oscillating case of (Re, St)

= (2300, 0). For example in Fig. 5, it is found that turbulent

motion starts at x = 0 mm in the oscillating case, while a

laminar-turbulent transition can be observed at x = 40 mm

in the non-oscillating case. The distribution of temperature

in the oscillating flame is more intense and more expanded

than that in the non-oscillating flame. These results suggest

that forced oscillation excites vortex motion in the flow

field to enhance mixing and chemical reaction processes

between the fuel and air in the flame.

Indeed the results presented in Fig. 6 on the

distribution of vorticity, ω, in the flow field, a large number

of solitary round vortices are formed by the oscillating

excitation of the fuel flow for the oscillating case of (Re,

St) = (2300, 0.0076). In particular, the formation of

complex vortex structures can be seen at several locations

in the flame (e.g., at x = 15 mm, 35 mm, 50 mm and 70

mm) for the oscillating flame case in Fig. 6. In contrast,

intensive vortex sheet extends in narrow region from x = 0

mm to 55 mm for the non-oscillating flame case in Fig. 6.

A comparison of the distribution of ω in Fig. 6 with that of

YCH4 in Fig. 4, it can be seems that the fuel is contained in

the vortices, and is transported extensively with the vortex

motion.

The results also show that the high intensity regions of

temperature and heat release rate, T and Q, are quite

different in general. The distribution of Q in diffusion

flames is limited to a very thin chemical reaction zone (the

flame zone), while the distribution of T is widely expanded

with the distribution of heated gas. The distribution of Q is

presented in Fig. 7 and shows the effect of the forced

oscillation on the flame zone. A comparison of the

distribution of Q in Fig. 7 with that of ω in Fig. 6 reveals


5

that the flame zone is stretched and intensified around or

between the vortices. It is distorted and rolled up inside the

vortices. At several downstream regions of x > 40 mm, the

flame zone is discrete and discontinuous due to quenching.

Such a complexity in the instantaneous 2-D patterns of the

flame for the oscillating case of (Re, St) = (2300, 0.0076)

is much larger than that for the non-oscillating case of (Re,

St) = (2300, 0).

Figure 8 shows the averaged heat release rate in the

y-direction, Qt [J/m3·s], obtained by averaging the

instantaneous 2-D distribution of Q (Fig. 7) at each point of

x in the y-direction. Therefore, Qt is a one-dimensional

function of x spatially, and instantaneous temporally. For

the case of (Re, St) = (2300, 0), Qt has a peak at the

laminar-turbulent transition point of x = 40 mm seen in Fig.

7 and gradually increases at the downstream regions of x >

50 mm, while Qt in the laminar flow region of x < 25 mm

is very low. In contrast, for the oscillating case of (Re, St)

= (2300, 0.0076), Qt increases more drastically at upstream

and midstream regions of 0 mm < x < 60 mm. In particular,

it should be noted that the high intensity peaks of Qt at x =

40 mm, 55 mm and 75 mm almost correspond to the

locations of complex vortex structures presented in Fig. 6.

This means that the heat release rate is intensified due to

the influence of complex vortex structures generated by the

oscillating excitation.

The physical mechanism of oscillating excitation

effect on Qt can be explained now. As seen in Fig. 9, the

forced oscillation excitation in the fuel flow generates a

large number of solitary round vortices in the flow field.

The flame zone (the boundary formed between the fuel and

air) is stretched around or between the vortices, and is

distorted inside the vortices. Since the fresh fuel and air is

fed into both sides of the stretching and distorting thin

flame zone due to the flow induced by the vortices, the

mixing and chemical reaction enhances to cause

intensification of the local heat release rate. In addition, the

stretching and distorting processes directly cause an

increase to the area of the flame zone. Thus, both the

increase in local heat release rate and flame zone area is

thought to be main reasons for the oscillating excitation

effect on Qt. However, reasonable stretching and distorting

are needed for intensification of the heat release rate,

because excessive stretching and distorting cause

quenching of the flame, as seen in Fig. 7.

Finally, the combustion load rate (CL), for both the

non-oscillating flame case at (Re, St) = (2300, 0) and

oscillating flame case at (Re, St) = (2300, 0.0076), are

estimated by carrying out the time- and space-average of

the instantaneous 2-D distribution of Q presented in Fig. 7.

The time-average period is determined as 0.02 s, which is

about six-times that of one cycle for the forced oscillation

of 300 Hz. The area of the space-average is chosen from 0

mm to 80 mm in the x-direction and from -30 mm to 30

mm in the y-direction, which corresponds to the visualized

area in Figs. 4, 5, 6 and 7. The values of CL for the

non-oscillating and oscillating flames were found to reach

3.82 × 107 W/m3 and 4.57 × 107 W/m3, respectively.

Therefore, it can be concluded that oscillating excitation

provides about 20 % improvement as compared to the

non-oscillating excitation case.

Conclusions

In this study, a methane-air diffusion jet flame excited

by forced oscillation was examined both experimentally

and numerically. The following conclusions can be made

from the results obtained.

The experimental observation at relatively low

Reynolds number provided the direct effect of oscillating

excitation on the flame shape and length. These results

were obtained by comparing the flames at two different

Reynolds and Strouhal numbers of (Re, St) = (151, 0) and


6

(151, 0.42).

Results at higher Reynolds number were obtained

using the numerical simulation. From the numerical

analysis, the changes in instantaneous 2-D distributions of

mass faction of fuel, temperature, vorticity and heat release

rate were examined in detail. Particularly, it was

recognized that the complexity of distribution patterns at

(Re, St) = (2300, 0.0076) is much larger than that at (Re,

St) = (2300, 0). The complex vortical structures increase

the local heat release rate and flame zone area to intensify

the averaged heat release rate.

A quantitative comparison of the combustion load rate

(temporally- and spatially-averaged heat release rate), CL,

for (Re, St) = (2300, 0) and (2300, 0.0076) showed

improvement of about 20 % due to the effect of oscillating

excitation. A goal of this study is to provide optimization of

CL on the (Re, St)-parametric plane by means of the

experiment and numerical simulation. The comparison of

the experimental and numerical results under the same

conditions of (Re, St) is in the works.

Then, the ideal value of CL from the numerical

analysis may not agree with the practical value in the

experiment, because the decay effect of oscillation inside

the pipes and burner is unavoidable in the experiment,

particularly at high frequency oscillations. However, for

relatively low frequencies, this oscillating excitation

technique may be available to stabilize and intensify the

continuously operating combustors as one of the industrial

applications.

References

1) J. A. Lovett, S. R. Turns, “Experiments on

Axisymmetrically Pulsed Turbulent Jet Flames,”

AIAA Journal, Vol.28, No.1, 1990, pp.38-46.

2) S. Kamiya, S. Noda, Y. Onuma, “Flame Holding

Control of Jet Diffusion Flame by Excitation of

Injection Velocity,” Proceedings of the 33rd

Combustion Symposium in Japan, Tokyo, 1995,

pp132-135, in Japanese.

3) Y. C. Chao, “Behavior of the Lifted Jet Flames under

Acoustic Excitation,” Proceedings of the Combustion

Institute, Vol. 24, 1992, pp.333-340.

4) Y. C. Chao, “Measurements of the Stabilization Zone

of a Lifted Flame under Acoustic Excitation,”

Experiments in Fluids, Vol17, 1994, pp381-389.

5) Y. C. Chao, “Effects of Flame Lifting and Acoustic

Excitation on the Reduction of NOx Emissions,”

Combustion Science and Technology, Vol. 113-114,

1996, pp. 49-65.

6) M. Hishida, K. Yamane, H. Namima, W. Masuda, “Jet

Structure and Combustion Characteristics of Jet

Diffusion Flame Excited by Acoustic Wave,” Journal

of the Japan Society for Aeronautical and Space

Sciences, Vol. 48, No. 558, 2000, pp. 213-219, in

Japanese.

7) F. A. Williams, “Combustion Theory (2nd Edition),”

The Benjamin/Cummings Publishing Company, Inc.,

Menlo Park, 1985, pp. 1-18.

8) K. K. Kuo, “Principles of Combustion,” John Wiley &

Sons, Inc., New York, 1986, pp. 161-230.

9) T. P. Coffee, A. J. Kotlar, M. S. Miller, “The Overall

Reaction Concept in Premixed, Laminar, Steady-State

Flames. I. Stoichiometries,” Combustion and Flame,

Vol. 54, 1983, pp. 155-169.

10) T. P. Coffee, A. J. Kotlar, M. S. Miller, “The Overall

Reaction Concept in Premixed, Laminar, Steady-State

Flames. II. Initial Temperetures and Pressure,”

Combustion and Flame, Vol. 58, 1984, pp. 59-67.

11) R. J. Kee, F. M. Rupley, J. A. Miller, “CHEMKIN-II:

A Fortran Chemical Kinetics Package for the Analysis

of Gas-Phase Chemical Kinetics,” Sandia National

Laboratories Report, SAND89-8009, 1989.


7

12) M. D. Smooke, “Reduced Kinetic Mechanisms and

Asymptotic Approximations for Methane-Air Flames,”

Springer-Verlag, Tokyo, 1991, pp. 1-28.

13) B. P. Leonard, “A Stable and Accurate Convective

Modeling Procedure Based on Quadratic Upstream

Interpolation,” Computer Methods in Applied

Mechanics and Engineering, Vol. 19, 1979, pp. 59-98.

14) S. V. Patanker, “Numerical Heat Transfer and Fluid

Flow,” McGraw-Hill, New York, 1980, pp. 126-130.

Function generator

Amplifier

Methane AirSpeaker

Burner

Regulator

flow meter

Cone-shape tank

Cylinder

Fig.1 Experimental apparatus

ox

y

CH4 d

Air(80%N2+20%O2)

Injector wall

0

0

0

=∂∂

=∂∂

==

yY

Tvu

i

y

Air inlet

0

0

0

0

i,i YYTTuu

v

====

Fuel inlet

0,

0

0

0),(

ii YYTT

vtyuu

====side

0y

0

0

0

=∂∂===

iYTTuu

v

Outlet

0

0

=∂∂

=∂∂

xTxv

0

0

=∂∂

=∂∂

xYxu

i0

0

=∂∂

=∂∂

xTxv

0

0

=∂∂

=∂∂

xYxu

i

Fig.2 Analytical model and boundary conditions

Fig. 3 Flame photograph

Re = 151St = 0 (f = 0Hz)

Re = 151St = 0.42(f = 70Hz)

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

00.10.20.30.40.50.60.70.80.91

Re = 2300 St = 0( f = 0Hz )

Re = 2300St = 0.0076( f = 300Hz )

YCH4[-]

Fig. 4 Distribution of mass fraction of fuel

y[m

m]

y[m

m]


8

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

0

500

1000

1500

2000

2500

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

T [K]

Re = 2300 St = 0( f = 0Hz )

Re = 2300St = 0.0076( f = 300Hz )

Fig. 5 Distribution of temperature

y[m

m]

y[m

m]

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

-15

-10

-5

0

5

10

15

ω[1/s]

Re = 2300 St = 0( f = 0Hz )

Re = 2300St = 0.0076( f = 300Hz )

Fig. 6 Distribution of vorticity

y[m

m]

y[m

m]

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

-30

-20

-10

0

10

20

30

0 10 20 30 40 50 60 70 80x[mm]

0.0E+0

1.0E+7

2.0E+7

3.0E+7

4.0E+7

5.0E+7

6.0E+7

7.0E+7

Q [W/m3]

Re = 2300 St = 0( f = 0Hz )

Re = 2300St = 0.0076( f = 300Hz )

Fig. 7 Distribution of heat release rate

y[m

m]

y[m

m]

0 10 20 30 40 50 60 70 800.00E+0

1.00E+7

2.00E+7

3.00E+7

4.00E+7

5.00E+7

6.00E+7

7.00E+7

8.00E+7

x[mm]

0 10 20 30 40 50 60 70 800.00E+0

1.00E+7

2.00E+7

3.00E+7

4.00E+7

5.00E+7

6.00E+7

7.00E+7

8.00E+7

x[mm]

Re = 2300 St = 0( f = 0Hz )

Re = 2300St = 0.0076( f = 300Hz )

Fig.8 Averaged heat release rate in y-direction

Qt[W

/m3]

Q

t[W/m

3]


9

Fresh Air

Fresh fuel

High heat release rate zoneFlame zone

Stretching

Stretching

Vortex Vortex

Distorting

Distorting

Fresh Air

Fresh fuel

High heat release rate zoneFlame zone

Stretching

Stretching

Vortex Vortex

Distorting

Distorting

Fig.9 Formation mechanism of high heat release rate zone

Documents

[American Institute of Aeronautics and Astronautics 42nd AIAA Aerospace Sciences Meeting and Exhibit - Reno, Nevada ()] 42nd AIAA Aerospace Sciences Meeting and Exhibit - Effect of