experiments on impinging intermittent sprays: dynamic behaviour of impact miguel rosa oliveira...

Experiments on Impinging Intermittent Sprays:Dynamic Behaviour of Impact

Miguel Rosa Oliveira Panão

Supervised by Prof. António Luis Nobre Moreira

public presentation of the research work

Members of Comissão de Acompanhamento de Tese Prof. José Carlos Fernandes PereiraProf. Paulo Manuel Cadete FerrãoProf. João Eduardo de Barros Teixeira BorgesProf. António Luis Nobre Moreira


Background

DIME – ENK6-CT2000-00101Title: DIrect injection spray processes MEchanisms to improve performance

WP3: Fundamental studies on droplets evaporation and impingement

Task 3.1 Experiments on the impingement of single droplets and polydisperse sprays on heated surfaces.Task 3.3 Fundamental studies of gasoline sprays with forced oscillations, with/without crossflow.


Doug Baker, TECAT Engineering Inc., ‘Plot of the Month’ initiative promoted by Tecplot, November 2003

Primary Droplets

Fuel InjectorIntake Manifold

Air Flow

Secondary Breakup

Spray/Wall Interaction mechanismsWall Film

Evaporation of droplets

Intake Valve

Wall Film Evaporation

Super CriticalFilm Flow

Airblast

Liquid Fuel

Elsaer, Samenfink, Hallman and Wittig (1994)

Primary Droplets


Air Flow

Secondary Breakup



Intake Valve



Airblast

Liquid Fuel


16% of total HC emissions due to liquid films.

- Cheng et al. (1993) -

15% of injected fuel remains liquid inside combustion chamber

1.5 increase factor in HC emissions between engine cold-start and

heated engine.- Meyer and Heywood (1999) -

Spray

Wall Air

Spray

Wall Air

Background


Fuel Sprayfuel characteristics injection conditions

surroundingenvironment

injector position &orientation

Breakup and Vaporization

Vapor

Fuel/AirMixture

DropletLiquid Film

impingement

adherencevaporization

adherence

secondary atomization

vaporization

vaporization

secondarybreakup

air carry

air carryflow throughsolid surfaces

Panão and Moreira, Experimental Characterization of an Intermittent Gasoline Spray Impinging Under Cross-Flow Conditions, Atomization and Sprays, vol. 15, 201-222, 2005.

Background


PhD Program Guidelines Present Contribution

part I

part II

part III

«...caracterizar os mecanismos de interação entre as gotas, a superfície e o escoamento de ar na região de incidência, onde a formação de estruturas coerentes de grande escala influenciam os processos de dispersão e vaporização. (...) os resultados serão analisados à luz dos modelos físicos existentes para descrever a dinâmica de sprays incidentes.»

«...os resultados obtidos nesta fase são relevantes para a optimização dos sistemas de admissão em motores multiponto.» « A formação de um filme de líquido (...) é uma questão de importância fundamental no desenvolvimento de métodos de paragem/arranque para diminuir o consumo de combustível..» «...estudo da interacção da fase dispersa com a fase contínua.»

«...pretende-se desenvolver um novo método de validação e de reconstrução do sinal para um sistema PDA de duas componentes, de forma a permitir obter a velocidade do fluido num referencial solidário com as partículas.» «...caracterização completa do processo de transmissão de calor entre o spray e a superfície em condições tanto estacionárias, como transientes.» «...determinação dos coeficientes de transmissão de calor depende da interacção de vários fenómenos que ocorrem quase simultâneamente quando múltiplas gotas incidem num filme de líquido (...) e de efeitos associados à temperatura, pressão parcial do vapor, turbulência do escoamento, etc.»

Original PhD Study Plan and Present Contribution

(in portuguese)

Characterization of spray impingement under cross-flow conditions with a 2D Phase Doppler Anemometer to quantify the time-dependent fluid dynamic interactions between an impinging intermittent spray and a cross-flow.Analysis of the expected influence exerted by the cross-flow on the impingement outcome.Measurement and analysis of the two-phase flow generated by the impact of an intermittent spray on a flat disc in order to demonstrate that predicting the outcome of spray impact requires a precise knowledge of the flow characteristics in the presence of the target..Quantification of dynamic exchanges between an impacting spray and a liquid film and analysis of its implications to the development of spray/wall interaction models.

Simultaneous measurements of the spray characteristics before impact and the surface thermal behaviour.

Development of a novel approach to characterize heat transfer processes in the impact of an intermittent spray on a heated surface (overall boiling curves).

Simultaneous measurements of the spray characteristics and the surface thermal behaviour on the entire spray impact area.

Gu

idelin

e 1

Gu

idelin

e 2

Gu

idelin

e 3

Gu

idelin

e 4

Gu

idelin

e 5

Gu

idelin

e 6

part I

part III

Task 1

Task 2

Task 3

Task 4

Task 5

Task 6

Task 7


Spray Impact Under Cross-Flow

Free Spray Spray Impact

Spray Impact With Cross-Flow

consequences of spray impact

• secondary droplets by splash and rebound• formation of a dynamic liquid film• formation of wall-jet vortex• decreases penetration rate less impact energy

consequences of cross-flow

• deviates small and slower primary drops• splash becomes relatively more important• enhances secondary drops production


Spray Impact

Task 1


• Mundo, Sommerfeld and Tropea (1995, 1998) dry surface• Cossali, Coghe and Marengo (1997)• Bai, Gosman and Rusche (2002) wetted surface• Wang, Chen and Hwang (2002)

Predictive Tool to Estimated Impingement Outcome Stick

Spread

Splash

Rebound

ri

Spray Impact Under Cross-FlowTask 2


WallEffect

U

Ed

Improves mixing process+

Increase film thickness-

Toroidal Vortex

Impingementof secondary droplets

Cross-Flow FD

Droplets dwell more time inside

the flow


TTL PulseWITHCross-Flow

WITHOUTCross-Flow

Splash

SplashRebound

Stick

SplashSpread

Rebound

SplashSpread

Rebound

SplashSpread

ReboundStick

Spread

ReboundStick

Spray Impact Under Cross-Flow



Free Spray

Spray Impact

spraysolid

surface+

spray impacting on solid surface

Panão and Moreira, Flow characteristics of spray impingement in PFI injection systems, Experiments in Fluids, available Online, 10 June 2005.

Spray Impact on DiscTask 3


Sivakumar and Tropea, Physics of Fluids (2001) 14: L85-L88

Cortesy of Ana Sofia Moita, MSc, 2005.

drop impact+ ... +

= ?spray impact

drop impact

Panão and Moreira, Flow characteristics of spray impingement in PFI injection systems, Experiments in Fluids, available Online, 10 June 2005.

Spray Impact on DiscTask 4


Spray Impact on Disc

s

k

N

i s LF,ik 1

m m m

sr

k k

sz

k k

NU

i ri s rs LF,ik 1

NU

i zi s zs LF,ik 1

m u m u p

m u m u p

s s

k k k

siki

ks ss

N N2 2 2 2

i i s s s LF,i dissk 1 k 1E

E E E

1 1m u d m u d E E

2 2

s

k

N

sk 1

Mi

mass fraction

m

1m

s

k k

N

s rsk 1

pUri ri

radial momentum fraction

m u

1m u

s

k k

N

s zsk 1

pUzi zi

axial momentum fraction

m u

1m u

diss ks sse

ki si

energy fraction

E E E1

E E

Liquid Film – Multiple Impacts cybernetic systemTask 4


Tropea and Roisman (2000) Correlations weighted with

Kinetic Energy (T&R) Correlations weighted with

Surface Energy (T&R)

Panão and Moreira, Flow characteristics of spray impingement in PFI injection systems, Experiments in Fluids, available Online, 10 June 2005.Tropea and Roisman, Modeling of spray impact on solid surfaces, Atomization and Sprays, vol. 10, 387-408, 2000.

Spray Impact on DiscLiquid Film – Multiple Impacts cybernetic system

number flux

axial momentum flux energy flux

Task 4

Flux of Secondary droplets

Flux of Primary droplets


Spray Cooling with Pulsed SpraysPrimary Droplets


Air Flow

Secondary Breakup



Intake Valve



Airblast

Liquid Fuel


Primary Droplets


Air Flow

Secondary Breakup



Intake Valve



Airblast

Liquid Fuel


Temperatura da Superfície (ºC)Fl

uxo

de C

alor

(W

/m

)FilmEvaporation

Vaporization/Boiling

Transition

Leidenfrost


Spray Cooling with Pulsed Sprays

Loureiro, Panão and Moreira, Simultaneous measurements of droplets characteristics and surface thermal behaviour to study spray cooling with pulsed sprays , 12th Int. Symp. App. Laser Tech. Fluid Mech., Lisbon, 2004.

Task 5



c p fg satf h ,D,U, ,k, ,C , ,h , T 0

2 2

0p p satc

fg p sat

C C Th D UD U D Uf ' , , , , ,

k k h C T

Nu = a Rem Prn Wep

1.51

50.254

ReNu 3.4 10

Ja

0.94

0.53 0.33

W eNu 0.34

Re Pr

Nu = a Rem Prn Wep Jaq Ecw

Arcoumanis and Chang, Experiments in Fluids, vol. 16, pp. 105-119, 1993.

New Correlation

Moreira, Carvalho and Panão, The Effects of Fuel Impact on Mixture Preparation in SI Engines with Port Fuel Injection, 7th Int. Conf. Eng. Auto., Naples, 2005.

Temperatura da Superfície (ºC)

Flux

o de

Cal

or (

W/m

)

FilmEvaporation

Vaporization/Boiling

Transition Leidenfrost

Task 5



tinj = 5 ms tinj = 10 ms

Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, in Press.

5 10 15 20 25 30 35Injection Frequency (H z)

150

160

170

180

190

200

210

TN

ukyi

am

a (

ºC)

t inj = 5 ms t inj = 10 ms


210

220

230

240

250

260

TLe

ide

nfro

st (

ºC)


150

160

170

180

190

200

210

TN

ukyi

am

a (

ºC)

t inj = 5 ms t inj = 10 ms


210

220

230

240

250

260

TLe

ide

nfro

st (

ºC)

0 2 4 6R adial coordinate (m m )

0

20

40

60

Tim

e A

vera

ge

H

eat

Flu

x (

kW/c

m2 ) C H F

Leidenfr o st


120

160

200

240

280

Su

rfa

ce

Te

mp

era

ture

(ºC

)


0

20

40

60

Tim

e A

vera

ge

H

eat

Flu

x (

kW/c

m2 ) C H F

Leidenfr o st


120

160

200

240

280

Su

rfa

ce

Te

mp

era

ture

(ºC

)

spray spatial heterogeneities

Task 6



Carvalho, Panão and Moreira, The thermal interaction of pulsed sprays with hot surfaces – application to Port-Fuel Gasoline Injection systems, 20th ILASS, Orlèans, 2005.

f inj

p sat fuel fgmax

inj impact

m tq C T T h

T A

R

impact 0 0

1q q r, 0 drd

A

max

q

q

Task 6



2min

w0 w0 inj inj w0min

q q T T f f T a

Carvalho, Panão and Moreira, The thermal interaction of pulsed sprays with hot surfaces – application to Port-Fuel Gasoline Injection systems, 20th ILASS, Orlèans, 2005.

ww f

qh

T T

Task 6


International Journals

Publications• Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, available Online at journal website, 16 June 2005.

• Panão and Moreira, Flow characteristics of spray impingement in PFI injection systems, Experiments in Fluids, available Online at journal website, 10 June 2005.

• Panão and Moreira, Experimental characterization of an intermittent gasoline spray impinging under cross-flow conditions, Atomization and Sprays, vol. 15, pp. 201-222, 2005.

• Panão and Moreira, Experimental study of the flow regimes resulting from the impact of an intermittent gasoline spray, Experiments in Fluids, vol. 37, pp. 834-855, 2004.

• Panão and Moreira, Visualization and Analysis of spray impingement under cross-flow conditions, Gasoline Direct Injection Engines 2002, SP-1719, pp. 135-145, SAE International, 2002.

International Conferences

• “The thermal interaction of pulsed sprays with hot surfaces – application to Port-Fuel gasoline injection systems”, Carvalho J, Panão MRO and Moreira ALN, 20th Annual Meeting of the Institute of Liquid Atomization and Spray Systems (ILASS), Orlèans, 2005.

•“The effects of fuel impact on mixture preparation in SI engines with port fuel injection”, Moreira ALN, Carvalho J and Panão MRO, 7th Int. Conf. Eng. Auto., Naples, 2005.

•"Time resolved heat transfer characteristics of an impinging gasoline spray", Panão MRO e Moreira ALN, 19th Annual Meeting of the Institute of Liquid Atomization and Spray Systems (ILASS), Nottingham, 2004.

• “Simultaneous Measurements of Droplet Characteristics and Surface Thermal Behavior to Study Spray Cooling with Pulsed Sprays”, H. Loureiro, M.R.O. Panão e A.L.N.Moreira, 12th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisboa, 2004.

• “Flow Characteristics of Spray Impingement in PFI Injection Systems”, M.R.O. Panão e A.L.N. Moreira, 12th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisboa, 2004.

• “Experimental characterization of spray-wall interaction under cross-flow conditions” Panão, M. R. O., Moreira, A. L. N., Proceedings of the 9th International Conference on Liquid Atomization and Spray Systems, Sorrento, 2003

• “Experiments on Impinging Intermittent Sprays: Dynamic Bahavior of Impact” A.L.N. Moreira, A.S. Moita, M. R. Panão, 3º Congresso Luso-Moçambicano de Engenharia, Maputo, 2003

• “Spray Impingement on a Flat Plate under Cross-flow Conditions”. M. R. Panão and A.L.N. Moreira 18th Annual Conference on Liquid Atomization and Spray Systems, Zaragosa, 2002.


Transmissão de Calor e Combustão (M/D)Tópicos Avançados em Mecânica dos Fluidos (M/D)Métodos Experimentais em Energia e Ambiente (L/M)Mecânica dos Fluidos Computacional (L/M)Economia, Energia e Ambiente (M/D)

Experiments

• Complete overall boiling curves for:

• tinj = 10 ms;• pinj = 4.5 bar;• Limp = 30 mm.

• Simultaneous measurements of spray characteristics and surface themal behavior over the entire impact area (PFI / GDI injector)

Curricula

PhD Program Progress

Geometric Optics


Phase Doppler Anemometer

scattering angle, 30º or 70º ?Visibility30º < Visibility70ºSignal Amplitude30º >> Signal

Amplitude70º

Validation30º > Validation70º

cross section area of measurement volume, A

1

cos1,

svNi i

qi i k k

qFlux

t A D

2tt s d sindL

Asin 4tan

Roisman and Tropea, Atomization and Sprays,vol. 11, pp. 667-700, 2001.

Considering s

t

LW

d sin cos

If Ls is small relatively to the drop direction angle, then slice intersection occurs.

22tt s d sindL 2

A 1 acos W W 1 Wsin 4tan

Panão and Moreira, Thermo- and fluid dynamics characterization of spray cooling with pulsed sprays, Experimental Thermal and Fluid Science, in Press.

experiments on impinging intermittent sprays: dynamic behaviour of impact miguel rosa oliveira...

Documents

impinging intermittent

outcome of spray impact

intermittent sprays

spray characteristics

impacting spray

entire spray impact

crossflow conditions

flow characteristics