Centrifugal pump design and analysis
COMPUTATIONAL FLUID DYNAMICS OF CENTRIFUGAL PUMP
AIM : To study the flow simulation of a centrifugal pump.
INTRODUCTION : Centrifugal pump is a hydraulic machine which converts mechanical energy into hydraulic energy by the use of cemtrifugal force acting on the fluid.It is used in places like agriculture,municipal,industrial power generation plants etc
CONSTRUCTION :
Various parts of centrifugal pump are :
- Impeller : It is a wheel or a rotar which is provided with a series of curved blades or vanes. It is mounted on the shaft which is coupled to an external source of energy which imparts liquid energy to the impeller ,therby making it to rotate.
- Casing : It surrounds the pipe rotar which transmitts energy to the fluid handled via the impeller.
- Delivery Pipe : It is a pipe which is connected to its lower end to the outlet of the pump and it delivers the liquid to the required height.
- Suction Pipe : It is connected with the inlet of the impeller and the other end is dipped into sump of water.At the water end it consits of Float Valve and strainer.
WORKING : Centrifugal pumps operate by transferring energy(angular momentum) from a rotating impeller to the fluid, which is inside a casing. Fluid enters the rapidly rotating impeller along its axis and is cast out by centrifugal force along its circumference through the impeller’s vane tips. The action of the impeller increases the fluid’s velocity and pressure and also directs it towards the pump outlet.
PROCEDURE :
First we modelled different parts such as impeller,casing,suction pipe, delivery pipe etc as required for the analysis of the centrifugal pump.
We then created a new flow simulation study and provided various input parameters such as wall conditions,water as working fluid and other thermodynamic conditions.
We also applied lids and shells as per requirement in the analysis
We then applied boundary conditions like enviromental pressure and velocity at inlet and outlet face respectively ,and also created mesh.
After that we added surface goal parameters,ran the study and analyise the result.
(To prevent convergence of the solution,enable proper number of iterations for better output )
RESULTS AND PLOTS:
After running the Parametric Study for 4 design points between 10 and 30m/s outlet velocity we obtain flow trajectories,cut plots for pressure and velocity which are as shown under:
For design point 1 (v= 10m/s)
Pressure cut plot 1 Velocity cut plot 1
For design point 2(v=16.667m/s)
Pressure cut plot 2 Velocity cut plot 2
For design point 3(v=23.33 m/s)
Pressure cut plot 3 Velocity cut plot 3
For design point 4(v= 30m/s)
Pressure cut plot 4 Velocity cut plot 4
FLOW TRAJECTORIES :
Flow trajectories for different design poimts is shown below.
We can see that as the number of points increases the flow trajectories become more and more clear.
CONCLUSION :
After running the parametric study for 4 design points and exporting the results to excel we see plots for inlet pressure , outlet pressure and mass flow rate which are as shown below.
Inlet pressure
Outlet pressure
Mass flow Rate
Please note that the mass flow rate is negative as the fluid is coming out of the centrifugal pump ,but here we need to consider only the magnitude for our calculation purpose.
Performance characteristic between pressure ratio and mass flow rate is as shown below.
We can see from the above graph that,as we increase the pressure ratio the mass flow rate also increases.
Matlab program for the above graph is as shown.
APPLICATIONS OF CENTRIFUGAL PUMP
Centrifugal pumps are used in buildings for pumping the general water supply, as a booster and for domestic water supplies.They are also used in fire protection systems and for heating and cooling applications. In addition, they are popular in the beverage, dairy, food and light chemical industries.
Please note that the excel file for plots of the Centrifugal pump is attached below