Centrifugal pump design and analysis using SOLIDWORKS.

AIM:

Performance diagram. Obtain the relationship between Pressure ratio and mass flow rate and explain your results.

INTRODUCTION:

A pump which is the heart of the hydraulic system converts mechanical energy into hydraulic energy. The mechanical energy is delivered to the pump via a prime mover such as an electric motor. Due to mechanical action, the pump creates a partial vacuum at its inlet. This permits atmospheric pressure to force the fluid through the inlet line and into the pump. The pump then pushes the fluid into the hydraulic system.

There are two broad classifications of the pumps:

1. Dynamic (Non-Positive Displacement) Pump;
2. Positive Displacement Pump

CENTRIFUGAL PUMPS: Centrifugal Pumps are the most popular and commonly used type of pump for the transfer of fluids. In simple words, it is a pump that uses a rotating impeller to move water or other fluids by using centrifugal force. These are the undisputed pump choice especially for delivering liquid from one location to another in numerous industries including agriculture, municipal (water and wastewater plants), industrial, power generation plants, petroleum, mining, chemical, pharmaceutical, and many others.

One thing is very important to understand that ‘Pump does not pump pressure’. Instead, they produce fluid flow. The resistance to this flow produced by the hydraulic system is what determines the pressure.

WORKING OF A CENTRIFUGAL PUMP:

Centrifugal pumps are used to induce flow or raise a liquid from a low level to a high level. These pumps work on a very simple mechanism. A centrifugal pump converts rotational energy, often from a motor, to energy in a moving fluid.

The two main parts that are responsible for the conversion of energy are the impeller and the casing. The impeller is the rotating part of the pump and the casing is the airtight passage that surrounds the impeller. In a centrifugal pump, fluid enters into the casing, falls on the impeller blades at the eye of the impeller, and is whirled tangentially and radially outward until it leaves the impeller into the diffuser part of the casing. While passing through the impeller, the fluid is gaining both velocity and pressure. The impeller in a centrifugal pump creates velocity through rotation;

CENTRIFUGAL PUMP IN SOLIDWORKS:

PARAMETERS FOR BASELINE SIMULATIONS:

Analysis type	Internal
Fluid used	Water
Type of flow	Laminar and Turbulent
Rotation type	Local Region Averaging

PROCEDURE:

• Create a model for the above specification.
• Extrusion of the pump should do through mid-plane and ensure merge results are turned off.
• Using a combined option combine inlet, pump, and outlet part.
• Now let us set up a flow simulation
• Setup an internal flow simulation and setup rotation flow simulation and choose fluid as water.
• now select a rotation domain i.e. the extrusion created around rotating blades should be considered rotation region and speed value are assigned as 1000 rad/s.
• The boundary conditions are applied.
• The inlet boundary condition is set to environmental pressure 101325 Pa.
• The parametric study is run for different outlet velocity say 10m/s, 15m/s, 20m/s, 25m/s, 30m/s.
• The surface goal for average total pressure is set up and mesh is refined automatically.
• The rotation region is not considered during the calculation as an object.
• The calculation iteration is set up to 500 for a calculation to run.
• Now the flow trajectories and the cut plot is set up. The flow trajectories are set up for 500 points and faces are selected.
• Now run the calculation.

CFD Analysis:

This project simulates a typical centrifugal water pump using the steady-state. The pressure-velocity coupling is performed through the SIMPLE algorithm. The project is concerned with the influence of pressure and velocity changes with the change in outlet velocity and draws a relationship between Pressure ratio and mass flow rate of the centrifugal water pump. The performance characteristic curves, as well as the local and global flow variables, are numerically predicted using SolidWorks Flow Simulation.

RESULTS:

OUTLET VELOCITY: 10 M/S

Cut Plots for Velocity

Cut Plots for Pressure:

OUTLET VELOCITY: 15 M/S

Cut Plots for Velocity:

Cut Plots for Pressure:

OUTLET VELOCITY: 20 M/S

Cut Plots for Velocity:

Cut Plots for Pressure:

OUTLET VELOCITY: 25 M/S

Cut Plots for Velocity:

Cut Plots for Pressure:

OUTLET VELOCITY: 30 M/S

Cut Plots for Velocity:

Cut Plots for Pressure:

PERFORMANCE DATA:

Velocity [m/s]	SG Av Total Pressure Outlet [Pa]	SG Av Total Pressure Inlet [Pa]	Pressure Ratio [Pa]	Mass Flow Rate
10	1004518.103	101324.9999	9.91382	-0.043969938
`15	350635.3265	101325	9.38204	0.227722471
20	877785.5231	101325.0023	8.66306	0.085127946
25	811710.1308	101325.0019	8.10095	-0.24264866
30	621535.011	101324.9987	6.13407	0.125454666

RELATIONSHIP BETWEEN PRESSURE RATIO AND MASS FLOW RATE:

Observation:

1. Firstly, we observe that with the increase in velocity, the total pressure at the output decreases gradually. So, this satisfies the working of an actual centrifugal pump where we get maximum pressure at the outlet.
2. The pressure ratio is calculated from the ratio of Outlet Pressure to Inlet pressure, which also seems to be decreasing.
3. The mass flow rate of the Pump is increasing with the increase in Outlet Velocity.
4. The graph plotted between the Pressure Ratio and Mass Flow Rate shows that the mass flow rate is inversely proportional to the Pressure Ratio.