CENTRIFUGAL PUMP DESIGN AND ANALYSIS

AIM: TO DESIGN A CENTRIFUGAL PUMP USING SOLIDWORKS AND SIMULATE THE FLOW

INTRODUCTION: 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.

At low mass flow rate operation, the pressure ratio over the impeller is high. The high back pressure, downstream of the impeller, pushes flow back over the tips of the rotor blades towards the impeller eye (inlet).

GOVERNING EQUATION:

• Pressure Ratio = Output Pressure / Input Pressure

PROCEDURE:

• Initially, a CAD model of Centrifugal Pump is set up with necessary dimensions. While extruding the geometry, the ‘Merge Result’ option is unchecked to avoid the merging of the existing geometry with the extruded geometry.
• To overcome the limitation of meshing in SolidWorks, ‘Moving Frame Reference’ is employed and a control volume is constructed to provide the rotation for simulation.
• A Flow Simulation is ideated with specified boundary conditions and goals to be obtained. Also, the iterations are fixed with a 500 value to avoid early convergence resulting in unsatisfactory results.
• A Parametric Study is set up with the variable being the Outlet Velocity. The simulation is run for 5 design points and the results are obtained for verification.

RESULTS:

VELOCITY CUT PLOT (at 10 m/s outlet velocity)

PRESSURE CUT PLOT (at 10 m/s outlet velocity)

VELOCITY FLOW TRAJECTORY (at 10 m/s outlet velocity)

PRESSURE FLOW TRAJECTORY (at 10 m/s outlet velocity)

INLET TOTAL PRESSURE (5 Design Points)

OUTLET TOTAL PRESSURE (5 Design Points)

MASS FLOW RATE (OUTLET)

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 Av Total Pressure 1 [Pa]	4267678.386	4005504.51	7142746.072	8956227.296	3504225.564
SG Av Total Pressure 2 [Pa]	548222.5187	499225.5611	1003775.859	1114661.211	475737.9097
SG Mass Flow Rate 1 [kg/s]	-0.491014285	-0.738724617	-0.973207386	-1.174373242	-1.480761672

CONCLUSION: The Simulation carried out gives a clear perception of the working of Centrifugal Pump. It can also be concluded that the impact of the mass flow rate is highly significant in determining the outlet total pressure, i.e. our required parameter dependency on the variables.