Centrifugal pump design and analysis
Aim:- To perform flow simulation of centrifugal pump using air as a flow medium
Theory:
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 vaccum cleaner. The reverse function of the centrifugal pump is a water turbine converting potential energy of water pressure into mechanical rotational energy.
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.
The flow analysis inside the centrifugal pump is highly complex mainly due to 3D flow structure involving turbulence, secondary flow, cavitation and unsteadiness. In recent years, a growing availability of computational resources and progress in the accuracy of numerical methods brought turbo machinery Computational Fluid Dynamics (CFD) methods from pure research work into the competitive industrial markets. The critical review of CFD analysis of centrifugal pumps along with the future scopes for further improvement is presented in this paper, CFD technique has been applied by the researchers to carry out different investigations on centrifugal pumps viz. performance prediction at design and off-design conditions, parametric study, cavitation analysis, diffuser pump analysis, performance of pump running in turbine mode etc. Unsteady Reynolds-averaged Navier-Stokes equations together with two equation k-e turbulence model were found to be appropriate for CFD analysis of centrifugal pump. Volute flow study and impeller-volute interaction appeared as an interesting research fields for the further improvement in the pump performance. The most active areas of research and development are the analysis of two phase flow, pump handling non-Newtonian fluids and fluid-structure Interaction
Objective:
To perform flow simulation of centrifugal pump to get velocity pressure plots and different inlet velocity. And also to get mass flow rate of medium used.
Centrifuegal Pump Design :
Without impeller zone
With Impeller zone
Setup For CFD
2. Rotating Region Setup
give angular velocty 1000 rad/s
3. Boundary Condition
4. Goal
Set average toal pressure at outlet .
For better convergence result set iteration upto 300 .
Now run the simulation .
Velocity Cut Plot
Flow trajectory
Parametric study results for VC , Av TP & FT are
Velocity cut plot at 10 m/s
Flow Trajectory At 10 m/s
Velocity cut plot at 13.33 m/s
Flow Trajectory At 13.33 m/s
Velocity cut plot at 16.66 m/s
Flow Trajectory At 16.66 m/s
Velocity cut plot at 20 m/s
Flow Trajectory At 20 m/s
Conclusion :
From the above simulation it can be conclude that the average total pressure at outlet is gadually increasing in starting point then decreased slightly after point 3 it again increasing with the increasing of velocty upto 20 m/s .Thus CFD is performed well on centrifuegal pump .