Jet Fuel Cavitation in a ConvergingDiverging Nozzle
Michael P. Davis and Patrick F. Dunn
Department of Aerospace and Mechanical Engineering
Particle Dynamics Laboratory
B032 Hessert Laboratory
University of Notre Dame
Notre Dame, IN 46556 USA
mdavis7@nd.edu
SPONSOR: Honeywell International, Incorporated
University of Notre Dame
AME - Graduate Student Conference
October 19, 2006
University of Notre Dame
Particle Dynamics Laboratory
Cavitation Fundamentals
Cavitation - “the
process of rupturing
a liquid by decrease
in pressure at
roughly constant
liquid temperature”
FLUENT simulation
Brennan (1995).
University of Notre Dame
Particle Dynamics Laboratory
Motivation - Honeywell Fuel Pump
• Honeywell product line includes
valves, flow controllers, and fuel
pumps
• Common to all devices is high
flow rates through very small
orifices, resulting in cavitation
• Presence of bubbles causes
damage to components, vibrations,
and a loss of pump efficiency
pitting damage caused by cavitation
University of Notre Dame
Particle Dynamics Laboratory
Problem Description
Void Fraction = f(x)
Pressure = f(x)
x
flow
spherical
bubbles
microbubble nuclei
originating from
microparticles or walls
slug-like
gas voids
bubbly shock
gas pockets
liquid
solid
Void Fraction = Gas Volume/Total Volume
University of Notre Dame
Particle Dynamics Laboratory
Bubble Dynamics - Raleigh Plesset
Equation
3


Ý


3
1
R
2

R
Ý
Ý RÝ2  Pv  PG  o   P (t) 
RR
 4 

o
 R 
2
 
R
R 

bubble inertia
Vapor
+
Gas
bubble contents
far field
pressure
in liquid
surface
tension
viscous
effects
bubble interface,
surface tension
R(t)
far field, P (t)
 - fluid density
 - fluid viscosity
University of Notre Dame
Particle Dynamics Laboratory
Raleigh-Plesset in a C-D
  
(continuity)
Nozzle


1  uA  0
1  A

t
x
u
u
1 C p
u 
t
x
21   x
(momentum)
2
Ca
C 
D2 R 3 DR 
4 1 DR 2
R 2      1 R3 

R1  R3  p 

Dt
2  Dt 
Re R Dt We
2 
 2
4 /3R 3 (x)
1 4 /3R 3 (x)
P  Pv
Ca  
1/2 U2
 (x) 
U2 Ro
We 

U Ro
Re 

Cp 
P(x)  Pv
1/2 U2
(bubble dynamics)
(void fraction)
(liquid tension)
(surface tension)
(viscosity)
(pressure forcing)

University of Notre Dame
Particle Dynamics Laboratory
Experimental Apparatus
Transducers measure DP
University of Notre Dame
Particle Dynamics Laboratory
University of Notre Dame
Particle Dynamics Laboratory
H2O
flow
JP-8
University of Notre Dame
Particle Dynamics Laboratory
Void Fraction by Laser Light Scattering
Flow direction
HeNe
laser
Vout = f(
Cavitation
Bubbles
Photo-diode
array
Test section
• Initialize counter and increment
each time voltage drops below
threshold
• Compute running average as a
function of time and look for
convergence
• Need a way to calibrate output
signal
University of Notre Dame
Running
average
Particle Dynamics Laboratory
flow
University of Notre Dame
Particle Dynamics Laboratory
flow
University of Notre Dame
Particle Dynamics Laboratory
H2O
flow
JP-8
University of Notre Dame
Particle Dynamics Laboratory
Maximum Flow Rate Estimate
• The experimentally determined JP-8 mass flux under choked
conditions can be used to identify the maximum volumetric flow rates
achievable for a given minimum flow cross-sectional area assuming
similar, fully choked flow conditions.
University of Notre Dame
Particle Dynamics Laboratory
Goals of Research - Summary
• Reliably predict cavitation in internal flows involving
hydrocarbon fuels.
• Obtain experimental void fraction and pressure profiles for
model comparison.
• Parallel experimental and computational approach is
focused on model development.
• Development of passive and active cavitation control
strategies.
University of Notre Dame
Particle Dynamics Laboratory