Centrifugal pump design and analysis

Aim: To perform a flow simulation on a centrifugal pump

Introduction & Basic Theory: Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. In a centrifugal pump water enters from one side and there is a rotor or impreller which is being rotated by means of an engine or an electric motor, which also leads to the suction of fluid once the centrifugal pump starts working. Once the fluid enters the pump the pressure in the sentrifugal pump increases and the fluid exits witha higher velocity.

In this case we will look for the flow pattern of water in the centrifugal pump, and analyse it for different exit velocity.

Case Setup:

1. Firstly we will model a centrifugal pump, giving a more detailing to the propellers as they are going to act as the heart of the centrifugal pump as per design consern. But in our case we will be providing the working domain to represent the working of the propellers.
2. Than we will model the inlet and outlet for the fluid.
3. Further after saving the model we will go to the flow simulation tab and provide the lids to obtain a closed setup for our simulation to take place.
4. Then we will set up a new wizard to get started with our simulation. For our setup we will provide water as our working fluid.
5. Further we will provide the initial boundary conditions to the setup. Also here we will be declaring the rotating domain desifing the working area for the propellers as discussed.
6. Than after that we will set the goals to obtain the desired results.
7. Once that is done we will run a parametric study to get the pressure difference at both the ends for our velocity ramge of 10 m/s to 30 m/s with an intervals of 5.

Observations:

The model of the centrifucal pump can be seen below. The model is kept a little transparent do that we can see the various parts and layouts.

After running the simulation we can see the flow of velocity and pressure flow through the centrifugal pump.

The velocity flow can be seen below:

The pressure flow can be seen as:

Below we can see the results for mass flow rate and the pressure at both openings and we can also see the pressure ratio in the tabular form.

Goal (Value)	Design Point 1	Design Point 2	Design Point 3	Design Point 4	Design Point 5
Velocity normal to face (Outlet Velocity 1) [m/s]	10	15	20	25	30
SG Mass Flow Rate 1 (Inlet) [kg/s]	0.461887783	0.686143435	1.005097285	1.206140804	1.478384453
SG Mass Flow Rate 2 (Outlet) [kg/s]	-0.497693275	-0.746563183	-0.995407159	-1.244212237	-1.493003928
SG Average Total Pressure 1 (Inlet) [Pa]	107349.7721	114848.5437	130290.8985	142979.3616	163781.727
SG Average Total Pressure 2 (Outlet) [Pa]	38775.25896	-329092.4696	-731271.1859	-1367330.088	-1757851.462
Pressure Ratio=Outlet Pressure/Inlet Pressure	0.361204856	2.865447477	5.612603753	9.563129062	10.73289124

The graphs for the plots obtained for the goals set are as below:

The mass flow rate at inlet:

The mass flow rate at outlet is as:

The pressure plot at inlet is as:

The pressure plot at outlet is as:

The flow trajectory of velocity and pressure for different output velocity is as:

At 10 m/s:

At 15 m/s:

At 20 m/s:

At 25 m/s:

At 30 m/s:

Thus as the output velocity increases the intake velocity also gose on increasing. Also as the velocity increases the pressure is decreasing at the output.

Conclusion:

Thus from the table we can see that as the velocity increases the mass flow rate also increases and the pressure ratio also increases.

Also from the animated video we can see that the fluid is being succed towards the center and due to the rotation of the propellers the velocity of the fluid increases and thus the output veliocity is higher than the input velocity.