Centrifugal pump design and analysis
Aim:
To create a basic model of centrifugal pump and to made the flow simulation on it.
Objectives:
- To create the basic model of centrifugal pump.
- To made the baseline simulation.
- To made a parametric study at different outlet velocity of the fluid.
- To obtain the relationship between pressure ratio and mass flow rate.
Centrifugal pump:
The centrifugal pump is used to transfer the fluid from one place to another especially to higher places. The main principle behind the centrifugal pump is that it converts the rotational kinetic energy into hydrodynamics energy. The centrifugal pumps operate as like as other pumps by creating the low pressure region. When the impeller is rotating, the low pressure region is created at the volute. The water or fluid at the high pressure region start flowing towards the low pressure region. The sucked water is then transmitted into required place and direction by means of pipes. The rotating motion of the impeller is provided by an electric motor.
There are various parts in the centrifugal pump. The major three parts are,
- Impeller
- Volute
- Pump casing
The impeller is the rotating part of the pump. The rotating motion of the impeller is provided by an electric motor. It create the low pressure region inside the volute to suck the water.
The volute increases the area for the sucked fluid to flow. Based on the impeller size and the pressure created by the impeller, the volute is designed.
The pump casing is the outer layer of the pump in which the impeller and the volute is enclosed.
Modelling of centrifugal pump:
The very basic model of the centrifugal pump is modelled for this flow simulation.
- Initially, the impeller for the pump is modelled.
- The impeller is made with circle of particular diameter.
- The 6 wings are made around the circle to made the impeller.
- Once the impeller was modelled, the volute of the pump is modelled over the impeller.
- The inlet valve and the exhaust valve of the pum is modelled.
- Once all the above parts are modelled, they are combine together to get the smooth connection between each other.
- Using shell option, the outer portions including volute and the two valves are made hollow.
Simulation setup:
Before starting to assign the simulation parameters, a casing line structure or a disk should be made around the impeller. This is beacause the mesh generated during the rotation of impeller is not fine or it will break during the rotation. To get the actual and absolute result, that casing helps us to made the simulation accurately by providing fine mesh at the impeller.
- Initially two lids are made at the inlet and the outlet valve of the pump.
- The lid provide us a closed domain to carry the internal flow simulation.
- In the simulation setup, internal flow is checked with the rotating option.
- The water is fixed as a simulation fluid.
- The boundary conditions are assigned with the environmental pressure value at the inlet valve.
- The outlet value has outlet velocity as a boundary condition.
- The rotating region should be assigned with proper angular velocity.
- The surface plots are assigned to get the values of inlet pressure, outlet pressure and the mass flow rate.
- The casing around the impeller should not act as a part during simulation. So it should be exclude from the simulation.
- Then a refined mesh is assigned.
- The total iterations for the simulation is assigned as 500.
Results and discussions:
Initially, the baseline simulation is made with the outlet velocity of 10m/s. Then a parametric study is made by varying the outlet velocity values from 10 to 30m/s. The 6 values including 10m/s and 30m/s is assigned for the simulation. We can pressure flow trajectories, velocity flow trajectories and velocity cut plot as a result.
Velocity cut plot:
Outlet velocity of 10m/s:
Outlet velocity of 14m/s:
Outlet velocity of 18m/s:
Outlet velocity of 22m/s:
Outlet velocity of 26m/s:
Outlet velocity of 30m/s:
Pressure cut plot:
Outlet velocity of 10m/s:
Outlet velocity of 14m/s:
Outlet velocity of 18m/s:
Outlet velocity of 22m/s:
Outlet velocity of 26m/s:
Outlet velocity of 30m/s:
Velocity flow trajectories:
Outlet velocity of 10m/s:
Outlet velocity of 14m/s:
Outlet velocity of 18m/s:
Outlet velocity of 22m/s:
Outlet velocity of 26m/s:
Outlet velocity of 30m/s:
Pressure flow trajectories:
Outlet velocity of 10m/s:
Outlet velocity of 14m/s:
Outlet velocity of 18m/s:
Outlet velocity of 22m/s:
Outlet velocity of 26m/s:
Outlet velocity of 30m/s:
Inlet pressure, outlet pressure and mass flow rate value:
The various inlet pressure, outlet pressure and mass flow rate values for different outlet velocity values are shown below,
Inlet pressure plot:
Outlet pressure:
Mass flow rate plot:
Pressure ratio vs mass flow rate:
Pressure ratio = outlet total pressure / inlet total pressure.
Animation videos:
The pressure and velocity flow trajectories video at the outlet velocity of 10m/s is shown below,
Pressure - https://youtu.be/9AiH1jRdYOE
Velocity - https://youtu.be/wMsrghtRnzA
CAD model:
https://drive.google.com/file/
Conclusions:
Thus the centrifugal pump is modelled and the simulation was done. This simulation provide the lot of parameters in the flow of fluid in centrifugal pump.
- The velocity plot explains that the velocity is maximum athe wings of impeller.
- The pressure plot explains the change in pressure corresponding to the outlet velocity.
- The pressure and velocity flow trajectories explain the appearance of pressure and velocity at the part of centrifugal pump 3D model.
- The pressure ratio vs mass flow rate plot varies unsteadily.