PART 2

Point A : L/D2=

0.2 (got backflow at pressure outlet)

Point B : L/D2=

0.35 (no backflow at pressure outlet)

Point C : L/D2= 0.

5 (no backflow at pressure outlet)

Point D : L/D2 = 0.65(no

backflow at pressure outlet)

Point E : L/D2= 0.

8 (no backflow at pressure outlet)

Point

F= L/D2= 0. 95 (no backflow at pressure outlet)

Point

G = L/D2= 1 (no backflow at pressure outlet)

Point H: =

L/D2= 1.15 (no backflow at pressure outlet)

Point I: =

L/D2= 1.3 (no backflow at pressure outlet)

Point J: =

L/D2= 1.45(no backflow at pressure outlet)

Point k: =

L/D2= 1.6(no backflow at pressure outlet)

Point L: =

L/D2= 2(no backflow at pressure outlet)

The best grid

resolution that was chosen in part 1 which is 0.009 min size ,0.04 max face

size and max size. However, with further

investigation at the direction of fluid flow to the pressure outlet.

It is to be found that there is a present of

reverse flow at the pressure outlet when is used the value ratio of L(extend) and

D2 which is 0.2.

With research , it is to be found that in order to avoid

reverse backflow of the fluid at the pressure outlet, one must increase the

ratio of L(extend)/D2. Hence, geometry of L(extend) are then be changed with

the aids of given data of L(extend)/D2. By using contour, the direction of flow

can be observed. The blue color arrow is found to be having the lowest pressure

flow, whereas, the red arrow is the opposite. Reverse backflow usually occurred

at lowest pressure flow.

For

investigating the backflow of fluid, 12 points have already tested by just keep

changing the L value. It shows that as the L value increase, the point values

also increase when the D2 value is constant. In this case, the only part need

to be focused more is wall surface instead of the diameter region since its

flow field is constant throughout. After all the

trials, in our simulation data, the shortest L(extend) to achieve no backflow

in pressure outlet is 0.35. this is because at this point, value reach

to 0.35 which is point B and its L value is 0.7mm, the backflow region still

can be seen but it start to decrease and become forward flow which is normal

flow in the end, this means that no backflow at pressure outlet.

PART 3

point

L/D2

L

P(inlet)

P1

pressure difference

% error

A

0.2

0.4

2.61E+06

7.14E+05

1.90E+06

—-

B

0.35

0.7

2.28E+06

3.26E+05

1.95E+06

2.564

C

0.5

1

2.10E+06

7.53E+04

2.02E+06

3.465

D

0.65

1.3

2.03E+06

-9927.47

2.04E+06

0.980

E

0.8

1.6

2.00E+06

34006.45

1.96E+06

4.082

F

0.95

1.9

1.97E+06

-13154.1

1.98E+06

1.010

G

1

2

1.93E+06

-77498.5

2.01E+06

1.493

H

1.15

2.3

1.94E+06

-60337.7

2.01E+06

0.000

I

1.3

2.6

1.90E+06

-71878.7

1.98E+06

1.515

J

1.45

2.9

1.88E+06

-109913

1.99E+06

0.503

K

1.6

3.2

1.90E+06

-83416.8

1.99E+06

0.000

L

2

4

1.91E+06

-25076.7

1.94E+06

2.577

For this part, 12 point with different L/D2 has been recorded. For this case, the diameter of the P(outlet) is

constant, so the ratio of L/D2 is can be indicated as the change for

Length(extend). The best grid resolution is then be used in part 3 with

different L(extend)/D2. The Pressure(inlet)

and pressure(line8) value was recorded by using the method above from part 2.

The pressure difference was also recorded in the table by using the formula ?P = Pin ? P1(line8). The result was

shown as table above. The percentage error is calculated by using the method

below.

With the aids of the formula, it is to be found that all the

percentage error are relatively low (