Centrifugal pump design and analysis

Aim: To perform design and simulation over a Centrifugal Pump and to plot the graph between pressure ratio and mass flow rate.

Theory: A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action, typically converted from electrical energy into Hydraulic energy. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps.

Different Types of Pumps: Working and Their Applications

There are different types of pumps available in the market. This article will assist you to know the main functionalities of each type of pump. The type of pump, as well as selection, mainly depend on our requirement. The application mainly includes the type of fluid you desire to pump, the distance you desire to move the fluid, and the quantity you require to get over a particular time frame. However, it is complicated to recognize accurately what kind of pump you must select. The identifying of the pump can be done with the design as well as positions. To make simpler things while seeking to choose your exact pump, and the pumps can be classified into two types which function in extremely dissimilar ways & generally summarize most of the pump designs.

Types of Pumps

Pumps are classified into two types namely Dynamic pumps as well as Positive Displacement Pumps.

Dynamic Pumps

Dynamic pumps are classified into different types but some of them are discussed below like Centrifugal, Vertical centrifugal, Horizontal centrifugal, Submersible, and Fire hydrant systems.

• Centrifugal Pumps

These types of pumps are most commonly used worldwide. The working is very simple, described well and carefully tested. This pump is strong, efficient and fairly cheap to make. Whenever the pump is in action, then the fluid pressure will increase from the inlet of the pump to its outlet. The change of pressure will drive the liquid throughout the system.

This kind of pump produces an enhancement within force by transmitting mechanical power from the electrical motor to the liquid throughout the revolving impeller. The flow of liquid will enter the centre of impeller and exits along with its blades. The centrifugal power hereby enhances the velocity of fluid & also the energy like kinetic can be altered to force.

• Vertical Centrifugal Pumps

Vertical centrifugal pumps are also called as cantilever pumps. These pumps use an exclusive shaft & maintain design that permits the volume to fall within the pit as the bearings are external to the pit. This mode of pump utilizes no filling container to cover the shaft however in its place uses a throttle bushing. A parts washer is the common application of this kind of pump.

• Horizontal Centrifugal Pumps

These types of pumps include a minimum of two otherwise more impellers. These pumps are utilized in pumping services. Every stage is fundamentally a divide pump.

All the phases are in a similar shelter & mounted on a similar shaft. On a solo horizontal shaft, minimum eight otherwise additional stages can be mounted. Every stage enhances the head by around an equal amount. Multi-stage pumps can also be single otherwise double suction on the first impeller. All kinds of pumps have been providing as well as servicing this type of centrifugal pumps.

• Submersible Pumps

These pumps are also named as storm water, sewage, and septic pumps. The applications of these pumps mainly include building services, domestic, industrial, commercial, rural, municipal, & rainwater recycle applications.

These pumps are apt for shifting storm water, subsoil water, sewage, black water, grey water, rainwater, trade waste, chemicals, bore water, and foodstuffs. The applications of these pipes mainly include in different impellers like closed, contra-block, vortex, multi-stage, single channel, cutter, otherwise grinder pumps. For different applications, there is an extensive selection is accessible which includes high flow, low flow, low head, otherwise high head.

• Fire Hydrant Systems

Fire hydrant pump systems are also named as hydrant boosters, fire pumps, & fire water pumps. These are high force water pumps intended to enhance the capacity of fire fighting of construction by increasing the force within the hydrant service as mains is not sufficient. The applications of this system mainly include irrigation as well as water transfer.

Positive Displacement Pumps

Positive displacement pumps are classified into different types but some of them are discussed below like diaphragm, gear, peristaltic, lobe, and piston pumps.

1. Diaphragm Pumps

Diaphragm pumps also known as AOD pumps (Air operated diaphragms), pneumatic, and AODD pumps. The applications of these pumps mainly include in continuous applications like in general plants, industrial and mining. AOD pumps are particularly employed where power is not obtainable, otherwise in unstable and combustible regions. These pumps are also utilized for transferring chemical, food manufacturing, underground coal mines, etc.

These pumps are responding pumps and include two diaphragms which are driven with condensed air. The section of air by transfer valve applies air alternately toward the two diaphragms; where every diaphragm contains a set of ball or check valves.

2. Gear Pumps

These pumps are a kind of rotating positive dislocation pump, which means they force a stable amount of liquid for every revolution. These pumps move liquid with machinery coming inside and outside of mesh for making a non-exciting pumping act. These pumps are capable of pumping on high forces & surpass at pumping high thickness fluids efficiently.

A gear pump doesn’t contain any valves to cause losses like friction & also high impeller velocities. So this pump is compatible for handling thick liquids like fuel as well as grease oils. These pumps are not suitable for driving solids as well as harsh liquids.

3. Peristaltic Pumps

Peristaltic pumps are also named as tube pumps, peristaltic pumps. These are a kind of positive displacement pumps and the applications of these pumps mainly involve in processing of chemical, food, and water treatment industries. It makes a stable flow for measuring & blending and also capable of pumping a variety of liquids like toothpaste and all kinds of chemicals.

4. Lobe Pumps

These pumps offer different characteristics like an excellent high efficiency, rust resistance, hygienic qualities, reliability, etc. These pumps can handle high thickness fluids & solids without hurting them. The working of these pumps can be related to gear pumps, apart from the lobes which do not approach into contact by each other. Additionally, these pumps have superior pumping rooms compare with gear pumps that allow them to move slurries. These are made with stainless steel as well as extremely polished.

5. Piston Pumps

Piston pumps are one kind type of positive dislocation pumps wherever the high force seal responds through the piston. These pumps are frequently used in water irrigation, scenarios requiring high, reliable pressure and delivery systems for transferring chocolate, pastry, paint, etc.

Model

Procedure:

1. For Design and Simulation of this problem first we will open solidworks and start modelling our part to do the flow simulation.
2. Now we will start designing the part but in this case we will use MKS system.
3. Now we will make two circles on of smaller size and one of bigger size and the we will draw an arc from the two using the three-point arc and then we will trim out the extra edges and we will extrude the part.
4. Now we will another circle slightly bigger than the blades which is the moving reference frame and then we will extrude slightly greater than the blades.
5. Now we will make another bigger circle than the previous one and now we will again extrude the sketch but with switching off the merge result option.
6. Now we will make another circle at the Front Face of the circle we made and then we will again extrude it with merge result which is our intake.
7. Now will make a line tangent to the larger circle and then we will make its horizontal line so that distance would be defined.
8. Now will make a circle on the face of the line and for this we will use reference geometry option in which first reference is line and second reference is the point. Now we will make a circle on the face on the line till to the other line and then we will use sweep command to extrude the part with not merging the result.
9. Now we will go for combine option and then we will combine the tangent extrude part and the bigger extruded cylinder we have created.
10. Now everything is done we will save the part and will go for flow simulation.
11. Now we will create the Lids at the two faces and then we will go for wizard and then internal flow problem and we will switch on the rotating region as local averaging.
12. Now we will click on water as the fluid and now we will click on ok.
13. Now we will be defining the Boundary condition at the inlet as 101325Pa and the other boundary condition as outlet velocity at the outlet face.
14. Now we will define the rotating region and then we will select the propeller domain which is the moving reference frame and then rpm of 1000 rad/s.
15. Now we will be adding the Surface goals at the inlet face and at the outlet face and then we will be calculation minimum and maximum velocity and pressure and also the flow trajectory.
16. Now we will do the parametric study using the input parameter as the outlet velocity and output parameter as the goals and results.

Results and Plots:

Case 1: At 2 m/s Outlet Velocity

Velocity Plot

Pressure Plot

Flow Trajectory

Case 2: At 4 m/s Outlet Velocity

Velocity Plot

Pressure Plot

Flow Trajectory

Case 3: At 6 m/s Outlet Velocity

Velocity Plot

Pressure Plot

Flow Trajectory

Case 4: At 8 m/s Outlet Velocity

Velocity Plot

Pressure Plot

Flow Trajectory

Case 5: At 10 m/s Outlet Velocity

Velocity Plot

Pressure Plot

Flow Trajectory

Goal Data

Pressure Data

Velocity Data

Flow Trajectory Data

Mass Flow Rate

Pressure Ratio vs. Mass Flow Rate

Conclusion:

• It can be observed that with increase in Velocity increases the Pressure Ratio decreases and hence Mass Flow Rate increases with negative sign. i.e. backflow
• With increase in Outlet Velocity the Maximum Velocity also increases.
• With increase in Outlet Velocity the Maximum Pressure decreases.
• With increase in Outlet Velocity the Average Mass Flow Rate showed a linear variation in the negative direction and hence it increases.