194
P. Liu
where V0 is the approaching velocity of the pool, V is the average velocity at
the pipeline section 2-2, H is the height difference between the centerline of
the pipeline outlet and the water surface of the pool, which is called the effective head of the pipeline and H 0 is the total head of the pipeline including
the approaching velocity head. Take α 2 ≈ 1.0, and the velocity at the pipeline
section 2-2 obtained from the above formula is
V = μ
2g H 0
μ =
1
1 + λ
L
d +
ξ
where μ is the velocity coefficient or flow coefficient of the pipeline. The
discharge through the pipeline is
Q = V A = μA
2g H 0
3.4.2 Water Pump System
The water pump system drives the water pump runner to rotate to work
on the liquid flow, so as to make the liquid flow from the low place to
the high place, as shown in Fig. 3.22. When the liquid flows through the
water pump, certain energy is obtained from the water pump, which is
input to the flow in the pressure pipe, and then flows into the water tower.
In hydraulic calculation, suction pipe flow and pressure pipe flow can be
calculated, respectively.
For the flow section of the suction pipe, the diameter of the suction pipe
and the installation elevation of the water pump are mainly determined. The
diameter of the suction pipe can be determined according to flow discharge
and economic velocity. If flow Q is known, the allowable flow velocity V in
the suction pipe is given, so the diameter d of the suction pipe is
d =
4Q
π V
For the installation elevation z s of the water pump, it is mainly determined
by the maximum allowable vacuum degree h v and the head loss of the suction
pipe. As shown in Fig. 3.22, the energy equation between section 1-1 and
section 2-2 is established with the water level of the water storage well as the
P. Liu
where V0 is the approaching velocity of the pool, V is the average velocity at
the pipeline section 2-2, H is the height difference between the centerline of
the pipeline outlet and the water surface of the pool, which is called the effective head of the pipeline and H 0 is the total head of the pipeline including
the approaching velocity head. Take α 2 ≈ 1.0, and the velocity at the pipeline
section 2-2 obtained from the above formula is
V = μ
2g H 0
μ =
1
1 + λ
L
d +
ξ
where μ is the velocity coefficient or flow coefficient of the pipeline. The
discharge through the pipeline is
Q = V A = μA
2g H 0
3.4.2 Water Pump System
The water pump system drives the water pump runner to rotate to work
on the liquid flow, so as to make the liquid flow from the low place to
the high place, as shown in Fig. 3.22. When the liquid flows through the
water pump, certain energy is obtained from the water pump, which is
input to the flow in the pressure pipe, and then flows into the water tower.
In hydraulic calculation, suction pipe flow and pressure pipe flow can be
calculated, respectively.
For the flow section of the suction pipe, the diameter of the suction pipe
and the installation elevation of the water pump are mainly determined. The
diameter of the suction pipe can be determined according to flow discharge
and economic velocity. If flow Q is known, the allowable flow velocity V in
the suction pipe is given, so the diameter d of the suction pipe is
d =
4Q
π V
For the installation elevation z s of the water pump, it is mainly determined
by the maximum allowable vacuum degree h v and the head loss of the suction
pipe. As shown in Fig. 3.22, the energy equation between section 1-1 and
section 2-2 is established with the water level of the water storage well as the