Centrifugal pump design and analysis

AIM:

• To create a 3d model of the centrifugal pump.
• To perform flow simulation with proper boundary condtitions and computational domain.
• To get the velocity trajectories and to plot pressure ratio vs mass flow rate.

Introduction:

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.

Solidworks flow simulation package is here used for 3d modelling and simulation.

Theory:

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.

Input Datas:

• Type of flow : internal
• Fluid used : water
• Outlet velocity : 10m/s, 20m/s, 30m/s
• Goals : total pressure at both inlet and outlet lids, mass flow rate at rotation chamber.

3d Model:

Pump is designed with random dimensions.

Simulation:

when outlet velocity 10m/s,

from the results obtained in simulation

inlet total pressure = 1023566.95 pa

outlet total pressure = 8199305.78 pa

Pressure ratio = 8.01

Mass flow rate = -0.00108493250369533 kg/s

Cutplots for pressure

Flow trajectories:

Simulaion results:

when outlet velocity 20m/s,

from the results obtained in simulation

inlet total pressure = 1189123.9 pa

outlet total pressure = 11057061.5823916 pa

Pressure ratio = 9.3

Mass flow rate = -0.00091378866338912 kg/s

Cutplots for pressure

Flow trajectories:

Simulaion results

Goals plot

when outlet velocity 30m/s,

from the results obtained in simulation

inlet total pressure = 159180.7 pa

outlet total pressure = 2183143.86462909 pa

Pressure ratio = 13.71

Mass flow rate = -0.000854650501802647 kg/s

Cutplots for pressure

Flow trajectories:

Goal plot:

Simulation results:

Simulation setup:

• The 3d model is drawn with approximate dimensions.
• Then the new project for simulation is createtd with wizard.
• Initial boundary condions, mesh and local mesh, cutplots, trajectories are created.
• Then new parametric study is created with diiferent outlet velocities.
• Then the simulation allowed to run.

Results Analysis:

• The simulation is sucessfully carried out for upto 300 iterations or unless the goals are achieved.
• The inlet and outlet total pressure is obtained as result with mass flow rate at rotation chanber.
• Exporting the solidworks results to excel.
• The pressure ratio is obtained by dividing the outlet total pressure by inlet total pressure.
• Plots are obtained by pressure ratio vs mass flow rate.

Plot:

1.

2.

Conclusion:

1. From the goal plots it is clear that the simulation carried until the goals plots are obtained.
2. Pressure ratio increases as the velocity increases.
3. The goal plots are obtained in less iterations as the veloctiy increases.
4. From the trajectories it is clear that the pump design needs to improve.
5. As the velocity increases the mass flow rate also slightly increases.