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)
F= L/D2= 0. 95 (no backflow at pressure outlet)
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.
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.
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
With the aids of the formula, it is to be found that all the
percentage error are relatively low (