Centrifugal pump design and analysis
OBJECTIVE
- To create a 3D Model of centrifugal pump.
- To plot the pressure ratio vs mass flow rate
THEORY ABOUT CENTRIFUGAL PUMP
Centrifugal pumps are used to transport fluids by the conversion of rotational kinetic energy to the hydrodynamic energy of the fluid flow. The rotational energy typically comes from an engine or electric motor. They are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. The fluid enters the pump impeller along or near to the rotating axis and is accelerated by the impeller, flowing radially outward into a diffuser or volute chamber (casing), from which it exits.
Common uses include water, sewage, agriculture, petroleum and petrochemical pumping. Centrifugal pumps are often chosen for their high flow rate capabilities, abrasive solution compatibility, mixing potential, as well as their relatively simple engineering. A centrifugal fan is commonly used to implement a vacuum cleaner. The reverse function of the centrifugal pump is a water turbine converting potential energy of water pressure into mechanical rotational energy.
Working
Like most pumps, a centrifugal pump converts rotational energy, often from a motor, to energy in a moving fluid. A portion of the energy goes into kinetic energy of the fluid. Fluid enters axially through eye of the casing, is caught up in the impeller blades, and is whirled tangentially and radially outward until it leaves through all circumferential parts of the impeller into the diffuser part of the casing. The fluid gains both velocity and pressure while passing through the impeller. The doughnut-shaped diffuser, or scroll, section of the casing decelerates the flow and further increases the pressure.
PROCEDURE
- First create a 3d model of a centrifugal pump with using some dimensions.
- After that go to the flow Simulation give the input parameters select the liquid as water.
- Then add the boundary conditions first rotation select the region of rotation at 1000 rad/sec, input is environmental pressure and outlet as velocity at 10 m/sec.
- The surface goal is set inlet and outlet for the total pressure and add the surface mass flow rate.
- Set the mesh grid automatically as level 3 and advanced channel refinement.
- Run the simulation and cut plot is created for the velocity and velocity trajectory.
3D Model
FLOW ANALYSIS
For this test, the input variables are outlet velocities at 10, 15, 20, 25 and 30 m/s and the level of mesh 3. The number of iteration for this test is 500 and mesh refine is set to advanced channel refinement.
Input parameters and Conditions
RESULTS
Velocity plot and Trajectory at 10 m/s
Velocity plot and Trajectory at 15 m/s
Velocity plot and Trajectory at 20 m/s
Velocity plot and Trajectory at 25 m/s
Velocity plot and Trajectory at 30 m/s
Pressure ratio = output pressure/input pressure
PRESURE RATIO AND MASS FLOW RATE
|
velocity [m/sec] |
SG pressure ratio [Pa] |
Mass flow rate [kg/sec] |
|
10 |
10.63866802 |
-0.492959249 |
|
15 |
8.302003801 |
-0.645287063 |
|
20 |
10.08859683 |
-0.980465112 |
|
25 |
8.91232757 |
-1.215313162 |
|
30 |
8.483350489 |
-1.432954981 |
Pressure ratio and Mass flow rate
CONCLUSION
- In the first figure we can see that, initially the velocity is less because of that the mass flow rate is also less, if when velocity increase then mass flow rate is also increases.
- Vealocity at 30 m/sec in that we can see that the mass flow rate is more compare to the velocity at 10m/sec. So that the velocity is more at the output and then pressure is less at the outlet
REFFERENCES