International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
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2
3

Abstract Fuel pump is an essential component on a car or other internal combustion engine device. The fuel pump is the heart of the fuel delivery system. Impeller electric fuel pump is a centrifugal type pump. The main component of impeller electric fuel pump is impeller and casing. In the impeller electric fuel pump, fuel enters axially through the impeller eye and fuel exits radially. The pump casing is to guide the liquid to the impeller, converts into the pressure energy having imparted to the liquid come from the volute casing. In this paper, impeller electric fuel pump is driven 60W electric motor and the design is based on
Euler equation. The head and flow rate of the pump are 0.34 m and 0.000546m
3 /s and motor speed is 1800rpm. Fuel pressure for a gasoline injection system can run from 15-40 psi
(100-280KPa).The number of blade is 48 blades. Shock losses, impeller friction losses, volute friction losses, disk friction losses, and recirculation losses are considered in the impeller electric fuel pump.
Keywords- Impeller Electric Fuel Pump, Blade Angle,
Head and Flow Rate, Losses, Flow Field Simulation system becomes restricted. This is a safety device to prevent the fuel lines from rupturing and damage to the pump.
Fuel pumps in most modern delivery systems are located inside the fuel tank, and run on electricity supplied by the vehicle’s electrical system. They pump at a continuous volume flow of fuel at a given voltage, and are typically extremely reliable when operated under the conditions for which they are designed. Basically, there are two types of fuel pumps: mechanical and electric. The latter is commonly use today. Electric fuel pumps important advantages over their mechanical counterparts. There are three common types of electric fuel pumps. They are impeller electric fuel pump,roller vane electric fuel pump and sliding vane pump.[1]
A. Impeller electric fuel pump
This is a centrifugal type pump. Normally, it is located inside the fuel tank. This pump uses a small D.C. motor to spin the impeller. The impeller blades cause the fuel to move outward due to centrifugal force. This produces enough pressure to move the fuel.[3]
I.
INTRODUCTION
Fuel pumps as a device that provides fuel to the carburettor or fuel injection nozzle. It pumps fuel from a vehicle’s fuel tank to the engine, where it is mixed with air and fuel and then injected into the cylinder for burning. The fuel pump is mounted in the tank and immersed in fuel. The fuel cools and lubricates the pump. When current flows through the motor, the armature and impeller rotate. The impeller draws fuel in through a filter and discharges pressurized fuel through the outlet port.
The fuel pump's pumping capacity is designed to exceed engine requirements. This insures that there will always be enough fuel to meet engine demands. An outlet check valve, located in the discharge outlet, maintains a residual fuel pressure in the fuel system when the engine is off. This improves starting characteristics and reduces vapor-lock.
Without residual fuel pressure, the system would have to be pressurized each time the engine was started and this would increase engine starting (cranking
) time. When a hot engine is shut off, fuel temperature in the lines around the engine increases. Keeping the system pressurized increases the boiling point of the fuel and prevents the fuel from vaporizing. A pressure relief valve will open if the fuel
Figure1 operation of impeller electric fuel pump
B. Roller vane electric fuel pump
This is a positive displacement pump (each pump rotation moves a specific amount of fuel). When the rotor disc and rollers spin, they pull fuel in one side. Then the fuel is trapped and pushed to a smaller area on the opposite side of the pump housing. This squeezes the fuel between the rollers and the fuel lows out under pressurize through the fuel lines.[4]
C. Sliding vane electric fuel pump
A sliding vane electric fuel pump is similar to a roller vane pump. Vanes (blades) are used instead of rollers.[4]
II.
DESIGN OF IMPELLER ELECTRIC FUEL PUMP
A. Design Procedure
This is a centrifugal type pump. The design pump is 60 watts motor drive impeller electric fuel pump. Impeller is
1
All Rights Reserved © 2012 IJSETR

International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012 designed on the basics of designed flow rate, pump head and pump specific speed. So, the design data are required to design the impeller electric fuel pump. For design calculation, the design parameters are taken as follows:
Flow rate, Q=0.000546m
3 /s
Head, H=0.34m
Pump speed, n=1800rpm
Gravitational acceleration, g=9.81m/s 2
Density of gasoline, ρ 
720kg/m 3
The design of impeller electric fuel pump involved a large number of interdependent variables so there are several possible designs for the same duty. One of the most difficult design problems is to predict the impeller head slip. The difference between the theoretical head for a number of impeller vanes and theoretical head deduced from the net horsepower given to the fluid passing through the impeller.
Before pump design or selection can be got.
Specific speed, n s
 n
3
Q
(1)
H 4
The shaft diameter at the hub section is: d s

3
16T
πS s
(2)
For commercial steel shaft, permissible shear stress is
24.5MN/m
2
2
 nT power, P

60
(3)
Impeller eye diameter,
D
0

K
0
3
Q n
(4)
Impeller inlet diameter,
D
1

(1.1
~ 1.15)K o
3
Q n
(5)
The outside diameter of impeller is
D
2


19.2
 n sopt :
100


1
6 2gH
(6) n
Inlet peripheral velocity, U
1
U
1

π
D
60
1 n
(7 )
Outlet peripheral velocity, U
2
U
2

D
2
 π  n
(8)
60
Impeller eye velocity,
V m0

K m0
2gH (9)
Vane inlet velocity,
V m1

K m1
2gH
Inlet blade angle of impeller is
(10)
β
1
 tan

1
(
K b1
V m1
U
1
) (11)
Where, K b1
=(1.1~1.25)
The value of K b1
chosen as 1.1
Blade number:
Z

6.5
D
2
D
2


D
1
D
1 sin(
β
1
 β
2
) (12)
2
The value of K b1
chosen as 1.1
Blade number:
Z

6.5
D
2
D
2


D
1
D
1 sin(
β
1
 β
2
) (13)
2
The blade outlet of impeller assumed as 130 degree.
Inlet width of the impeller is; b
1

Q
πD
1
V m1
ε
1
( 14 )
Blade outlet of impeller assumed as 130 degree. outlet width of the impeller is; b
2

Q
πD
1
V m1
ε
1
( 15 )
Fig.2. Inlet and outlet velocity diagram
V u2

U
2

V m2 tanβ
2
(16)
The virtual outlet angle,
α
2
 tan

1
V m1
V u2
(17)
Safety factor,
S.F

1

Z

 1




πsinβ
V
U m2
2
2

 cotβ
2



(18)
S.F

V
' u2
(19)
V u2
The absolute velocity ,
V
2
 
V 2 m2

U
2
'
2
(20)
The actual outlet angle,
α 
2
 tan

1
V m2
U
'
2
(21)
Volumetric efficiency,
η v

1

1
1.124
(22) n s
3
2
2
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International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
III.
PERFORMANCE OF IMPELLER ELECTRIC
FUEL PUMP
A .The theoretical head ,
The Euler head is determined from zero to maximum theoretically attainable flow using.
H th

1 g
U
Where, V
2
V u2
The whirl velocity, V u2

U
2

V m2 cotβ
2
(23) m2
and β
2
are outlet flow velocity and outlet blade angle.
B .Net Theoretical Head
If the slip factor is known, the net theoretical head may be obtained from Euler’s head.
Slip value is obtained by using the following equation.


2
1
2
0.7
The whirl velocity at the outlet,
u 2

2

m2
2
Where, ϭ is slip value
thn

2
u2
C .Shock Losses
The major loss considered is shock at the impeller inlet caused by the mismatch of fluid and metal angles. Shock losses can be found everywhere in the flow range of the pump. Shock Losses are given by Equation 27. [07Khi]
The shock loss
s

s

N
2
Maximum flow rate,
N

1
1
m1
The shut-off head, H shut
 off

U
2
2 
2g
U
2
1
(29)
In the shut-off condition, Q=0,h s
=H shut-off
D. Impeller Friction Losses
The impeller were designed that the width of the impeller would become small and the friction loss at the flow passage would become large. Therefore, to relive the increase in friction loss, radial flow passage on the plane of the impeller was adopted. The friction losses can be found for energy dissipation due to contact of the fluid with solid boundaries such as stationary vanes, impeller, casing, disk and diffuser, etc. The impeller friction loss is estimated by using Equation 31.
The hydraulic radius is calculated by using Equation
(30)
H r
 b
2 b
2

πD
Z
2
πD
2
Z

 sin β
2

 sin β
2
(30)
The impeller loss of head, h
1
 b
2
(D
2

D
1
)(V r1

V r2
)
2
(31)
2sin β
2
H r
4g
E. Volute Friction Losses
This loss results from a mismatch of the velocity leaving the impeller and the velocity in the volute throat. If the velocity approaching the volute throat is larger than the velocity at the throat, the velocity head difference is lost. The velocity approaching the volute throat by assuming that the velocity is leaving the impeller. [07Khi]
The volute friction losses are calculated by using
Equation 31.
C v
V
3
2 h
2

(31)
2g
The volute flow coefficient is obtained Equation 3.30.
v



vm
vm
investigated.
[07Khi]
3
5
3

9
s
The angular velocity ω,

3
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International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
G .Recirculation Losses
The recirculation loss coefficient depends on the piping configuration upstream of the pump in addition to the geometrical details of the inlet. The power of recirculation is also divided by the volume flow rate, like the disk friction power, in order to be converted into a parasitic head.
The recirculation loss, h
4

K ω 3
D
1
2
(1

Q
Q s
0
)
2.5
(35)
The pump speed is carried out with the value of specific speed because impellers with relatively large inlet diameters
(usually encountered in high-specific-speed pumps) are the most likely to recirculation. Coefficient of leakage loss K is assumed as 0.0005 [07Khi]
Figure.3. Prediction of Characteristic Curve of Impeller
Electric Fuel Pump
The performance of the impeller electric fuel pump is described by a graph plotting the head generated by the pump over a range of flow rates. A typical pump performance curve are included its efficiency and, both of which are plotted with respect to flow rate. The output of a pump running at a given speed is the flow rate delivery by it and the head developed.
Thus, head is against flow rate at constant speed forms fundamental performance characteristic of a pump. In order to achieve this performance, a power input is required which involves efficiency of energy transfer.
The efficiency of a pump is the ratio of the pump’s fluid power to the pump shaft horsepower. An important characteristic of the head/flow curve is the best efficiency point. At the best efficiency point, the pump operates most cost-effectively both in terms of energy efficiency and maintenance considerations. The efficiency of a impeller electric fuel pump depends upon the hydraulic losses, disk friction, mechanical losses and leakage losses [07Khi].
TABLE I
BASE CIRCLE RADII AND BLADE CURVE ANGLES
Base radius
R
A
R
B
R
C
R
D circle mm
20.5
18.98
17.46
15.95 angle
β
2
β
B
β
C
β
1 degree
130
92.34
54.69
17.26
IV.
Fig .4.3D drawing of Impeller Electric Fuel Pump
NUMERICAL ANALYSIS OF IMPELLER
ELECTRIC FUEL PUMP
In this study, the Solid Works simulation is used to simulate the impeller electric fuel pump. The parameters of the impeller electric fuel pump are listed in Table II. This analysis states the pressure and velocity distribution of the impeller electric fuel pump.
The inlet and outlet boundary conditions were taken. Inlet fuel of 0.000546m
3 /s volume flow rate having uniform velocity profile with vector parallel to the pump’s axis; at the radial-directed outlet at a static pressure of 250KPa is specified. Table II, III and IV shows inlet and outlet boundary conditions.
TABLE II
PARAMETERS OF IMPELLER ELECTRIC FUEL PUMP
Parameters
Flow rate
Data
0.000546m
3 /s
Rotational Speed 1800rpm
Shaft diameter
Hub diameter
Hub length
4mm
8mm
8mm
Impeller inlet diameter
Impeller outlet diameter
Shrould thickness
Vane inlet angle
Vane outlet angle
29.57mm
38.38mm
1mm
16.48degree
130degree
Inlet passage width
Outlet passage width
9.24mm
7.39mm
TABLE III
F LOW S IMULATION O F I MPELLER E LECTRIC F UEL P UMP
Research
Title
Unit
System
Analysis
Type
Design of In-Tank Electric Fuel Pump for EFI
Gasoline Engine
SI
Velocity distribution
Physical feature
Rotation:
Type: Global Rotating
Rotation axis: Z axis of Global Coordinate
System,
Rotational Speed=1800RPM
Default
Fluid
Wall condition
Initial
Condition
Ethanol
Adiabatic wall, default smooth wall
Default Condition
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International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012
TABLE IV
I NLET A ND O UTLET B OUNDARY C ONDITION
Type
Name
Face to apply
Inlet Volume
Flow
Inlet Volume
Flow
The inner face of the inlet lid
Parameters:
Volume Flow Rate Normal
To Face
Type Environment pressure
Name Environment
Pressure1
Face to apply The inner face of outlet lid
Parameters:
Static pressure:250KPa
A. Research Goal
First,since the pressure and volume flow rate boundary condition are specified,it makes sense to study the pressure and velocity distribution by changing outlet blade angle.The flow rate at the pump’s inlet and outlet to inspect the pressure and velocity balance as an additional criterion for converging the calculation. Table V show goal type and goal parameter.
Goal Type
TABLE V
R ESEARCH G OAL
Goal Parameter Face
Surface Goal
Surface Goal
Av static pressure The inner face of the inlet lid
Av velocity The inner face of the inlet lid
B.Simulation and Analysis of Inner Flow Field
Pressure and velocity distribution for different blade outlet angle of the impeller electric fuel pump is shown as below
Fig.7.pressure distribution for outlet blade angle,β2=125˚
Fig.8.Velocity distribution for outlet blade angle,β2=125˚
Fig.9.pressure distribution for outlet blade angle, β2=120˚
Fig .5.pressure distribution for outlet blade angle, β2=130˚
Fig .6.velocity distribution for outlet blade angle,β2=130˚
Fig.10.velocity distribution for outlet blade angle, β2=120˚
From the figure, it can be seem that for different blade angle, the pressure and velocity distribution gradually increase from the impeller inlet to outlet, the velocity and pressure on the discharge side are evidently larger than on the suction side at the same impeller radius. With the increasing blade outlet angle, pressure and velocity distribution are better. Blade outlet angle effects velocity of the impeller.
V.
C ONCLUSIONS
The designed pump is aimed to use in EFI Gasoline engine working and requires low head and capacity. So, impeller electric fuel pump type is selected. The casing is volute casing type. The design head is 0.34 m and the discharge is
0.000546m
3 /s. The pump can run at 1800 rpm to. The impeller inlet is 29.57 mm and the outlet diameter is 38.38
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All Rights Reserved © 2012 IJSETR

International Journal of Science, Engineering and Technology Research (IJSETR)
Volume 1, Issue 1, July 2012 mm. The inlet blade angle has 16.48°and the outlet blade angle of impeller has 130°. The impeller thickness is 0.2 mm to layout the impeller blade. A volute casing is also calculated from the impeller outlet dimensions. The outlet diameter of the volute casing is 46.83 mm and the shroud thickness is
1mm and clearance is 0.8mm. The volute width is 10.99mm this is very important to start the volute casing.
In a today, competitive and sophisticated technology, impeller electric fuel pump is more widely used than any other mechanical fuel pump because the advantages of following factors are affected on the impeller electric fuel pump.
1.
It delivers enough fuel to supply the requirement of the engine under all operating conditions: fuel not used is returned to the tank.
2.
3.
It prevents premature fuel evaporation, and reduces fuel consumption.
It maintains enough pressure in the line between the carburetor and the pump to keep the fuel from boiling.
4.
5.
6.
It prevents vapour lock.
It supplies an amount of fuel greater than the engine consume.
It can run at high speed without the risk of separation of flow.
The design of impeller electric fuel pump is also predicted in this paper. The impeller diameter, velocity and losses are considered on the impeller electric fuel pump. Moreover, design drawing of impeller and casing are also considered.
Flow simulation of pressure and velocity distribution for the impeller is studied by changing blade outlet angle (Solid
Works software).
[3] James Dr.Halderman
, Automotive fuel and Emission control system,
3 rd
Edition
[4] Daimler Chryster, fuel delivery system, ( 2000)
[5] Kyushu Institute Technology , Training Course, Japan : Kyushu
Institute of Technology . Fluid Mechanics of Turbo machinery,
(1996).
[6] Igor, J, Joseph, P, and Charlees , C, Pump Hand Book. USA : McGraw
Hill Company,(2001 )
[7] Ma Khin Cho Thin, Design and Performance Analysis of Centrifugal pump , (2007).
[8] Stepanoff, A.J
, Centrifugal and Axial Flow Pump,( 1957)
[9] Austin. H. Church , Centrifugal Pump and Blower. New York : John
Wiley and Sons, Inc.(1972)
[10] Herbert Addison , Centrifugal and Other Roto dynamic Pumps:
Chapan and Hall. Ltd,(1995)
A CKNOWLEDGMENT
The authors would like to thank U Hla Min Tun and Dr Thein
Min Htike, Department of Mechanical Engineering,
Mandalay Technology University.
N OMENCLUTURE
Q2
Symbol Description
β
β
2
1
Blade inlet angle
Volute base width b
1 b
D
D
2
D
0
1
D
2
3
Inlet passage width
Outlet passage width
Impeller eye diameter
Impeller inlet diameter
Impeller outlet diameter
Volute base circle diameter
D h
Hub diameter ds n
Shaft diameter
Rotational speed n s
Specific speed
P motor
Rated output power of electric motor
Q s
Flow rate per sec
U
U
2
V m0
V m1
V m2
Q
1 s
Q' s
Peripheral velocity at the inlet
Peripheral velocity at the outlet
Impeller eye velocity
Vane inlet velocity
Vane outlet velocity
Flow rate per sec
Flow through the impeller
R EFERENCES
[1] Courtesy Robert Bosch , Automotive Technology (Courtesy Daimler
Chrysler Corporation), ( 1990)
[2] Training Manual of Electric Fuel Injection (EFI) Toyota Motor
Corporation,( 2000)
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