'Centrifugal Pump with MRF' simulation project by Ali_Arafat


#1

I created a new simulation project called 'Centrifugal Pump with MRF':

This project simulates a Centrifugal water pump.


More of my public projects can be found here.


#2

Description


 

 
Being used in large-scale utilities such as thermal power plants and petrochemical pumping to something as basic as a household vacuum cleaner, centrifugal pumps have found a plethora of applications in a variety of industrial sectors. Fundamentally, a centrifugal pump is a mechanical device that imparts kinetic energy to the fluid passing through it. The impeller is connected to an electric motor, which in turn spins the impeller at a high velocity. As the fluid enters through the inlet, it comes in contact with the blades of the impeller. These blades set the fluid in a rotational motion, resulting in the fluid to move radially outward as an outcome of a centrifugal force obtained due to this motion.
 
The performance of the pump depends on a series of factors viz. number of impeller blades, design of blade profile and casing, airflow rate and pressure. A simulation using Computational Fluid Dynamics (CFD) is handy to effectively analyze and optimize the design of a centrifugal pump. In practice, there are primarily 2 models that are used to conduct this analysis:
 

  1. Multiple Reference Frame Model (MRF)
  2. Sliding Mesh Model
     

Project Goals


 
In this project, we shall use the Multiple Reference Frame Model (MRF). Essentially, the MRF is a steady-state approximation in which individual cell zones move at different rotational and/or translational speeds[1]. This means that the meshed regions (cell zones) that contain a specific material are in different frames of reference with respect to each other.
 
Therefore, we simulate a centrifugal water pump using the Steady State, Multi-Reference-Frame method (MRF) and K-Omega SST turbulence model .
 

Geometry


 
The geometry includes a standard backward type pump impeller enclosed within volute casing. The initial source of the geometry was a CAD model by GrabCAD user Reza Maleki . The overall dimensions of the geometry are provided in the figure below. The flow is intake axially from the inlet pipe and exited from the shown outlet. A separate region was created to specify the MRF zone in the vicinity of the impeller.
 


 

Meshes


 
The domain is the geometry itself and was meshed using the Snappy-Hex-Mesh available on the SimScale platform. The resulting mesh consists of approximately 3.4 million cells and is shown in the figures below:
 


 

 

Simulations


 
After the meshing operation, we run a simulation using the MRF and k-omega SST turbulence model. Depending upon the requirements, different boundary conditions are chosen. For this case, a mass flow inlet condition with a static pressure outlet is used. To obtain an accurate, desired pressure rise, the flow parameters for the pump should be known.
 
In this case, arbitrary values are used to demonstrate an operation example. At the inlet, a mass flow of 3 kg/s was assumed along with a static pressure value of 0 at the outlet. Also, the MRF zone was assigned a rotational velocity of 157 rad/s (1500 rpm).
 
With the given data, the simulation analyzes the mean velocity and pressure field in the pump.
 

Results and Conclusions


 
The results displayed below are processed on ParaView, a scientific visualization software. They accurately depict the velocity vectors and pressure rise at the outlet for a cut section of the pump. The simulation provides an adequate insight into the extent of pressure rise created by the pump, for a given mass-flow rate and rotational speed.
 


 
Pressure Contours
 

 


 
Velocity Vectors
 

 
Velocity Streamlines


#3

@Ali_Arafat: A great simulation! If the negative volume (flow volume) was not available, was there any possibility to mesh this device?


#4

@Ali_Arafat: I am really interested to know how you could handle the following simulation: https://www.simscale.com/customers/engineering-office-dr-heiser/


#5

Hi @roozbehmousavi ,

Thanks for your comments.
Yes , you can mesh the full geometry without extracting the negative volume with the “SnappyHexMesh” but given that it is water tight. Even having self intersecting faces is not an issue.
But, If the inlet and outlet sections are not a closed surface, then they should be first closed to generate the fluid inlet/outlet faces. Ofcourse, the rotating MRF zone must be defined by a separate solid included in the CAD file.

As an example for meshing the inside of a geometry without extracting the negative, you can see this project:
https://www.simscale.com/projects/Ali_Arafat/car_cabin_air_flow_analysis

where the complete car geometry was imported, but only the negative inside ( flow domain) was meshed.

I hope this helps to answers your question.

Best,
Ali


#6

For the simulation you mention: Regarding the meshing without extraction of the negative volume, the same approach can be used for meshing. However, the inlet and outlet sections are now Not closed surfaces for the shown geometry.

Given that we can easily add a solid for the rotating zone. Here, in theory we could use a slightly faster ( but not normally recommended ) approach to mesh the fluid volume as the geometry is simple and the inlet/outlet sections are oriented in a perpendicular manner .

We can use the ’ base mesh box’ to deliberately intersect and truncate the inlet and outlet sections . This would then create surfaces automatically during the meshing process for the inlet/outlet sections of the fluid domain and you would get the negative volume mesh without extraction.

I hope this helps.

Best,
Ali


#7

@Ali_Arafat: Will this model be valid for cavitation in centrifugal pump? If not please suggest analysis type for the cavitation.
Thanks in advance


#8

Hi @pratapkumar

We do not currently support Cavitation modeling in the available analysis types. In the future, we might look to include such models.

Best,
Ali.


#9

Interesting 


#10

Hello @Ali_Arafat


I am new to simscale Community. I saw your profile with projects, they are really helpful and knowledgeable. We manufacture centrifugal radial and mixflow submerged pumps and I was looking for some cfd software and found this cloud service. I had worked with other platforms like Ansys, Pumplinx etc for our complex geometry. Is it possible for you to provide a tutorial video for this centrifugal pump project to get started with Simscale.


Regards


#11

Hi @SHARADBORANA,

It’s nice to hear that you find my project helpful and that are you are interested in a CFD software for pumps. The SimScale platform can surely help you do that.

Pumps and other rotating machinery are slightly tricky to setup and require some important steps. To get you started please see the step by step tutorial for Meshing such geometries and creating a rotating zone.

  • Meshing Tutorial for rotating machinery (pumps, fans) see Here

  • To understand the Meshing process and settings, see the documentation Here

Once you are good with the meshing tutorial, please see my project (you can copy it and take a detailed look) for the simulation setup.

[For interflow pump application, you can either use the negative volume or the physical volume as the solid bodies to import. In addition to the pump geomerty you would need an additional solid region that covers the rotor to define the rotating zone.]

Let me know if you need further help.

Thanks
Best,
Ali Arafat
CFD Applications Engineer


#12

Hello @Ali_Arafat

thankyou very much for your kind support, I appreciate that. I will see the tutorial for meshing as it has a very important role in post processing results but how to created named selection in geometry for boundary condition like INLET, OUTLET, ROTATING and STATIONARY. I have extracted the fluid domain in my cad and uploaded that fluid domain in simscale in step format. My geometry has fluid volume with Impeller(rotating) and diffusser(stationary) bot had veins 6, 10 respectively.

thanks

SHARAD BORANA


#13

Hello@Ali_Arafat

Great work done by you. I had imported industrial centrifugal fan geometry in SIMSCALE. Regarding meshing the geometry in geometric primitives how can we specify the background mesh box. Actually in centrifugal fan/pump we analyze the flow scroll housing and my doubt is how can we specify scroll housing as background mesh box. And please attach your simulation tutorial if possible


#14

Hi @umamahesh,

you can have at the setup (and the Background Mesh Box) in the project itself: Centrifugal Pump

To copy this project into your workspace and make adapations, simply follow the instruction given in the picture below.

Best,

Jousef


#15

Hi@Jousefm

Appreciating for your immediate reply. Please suggest me the best software
for modelling the industrial fans like axial and centrifugal models which
support by the SIMSCALE.

klimatechnik


#16

How many prism layers did u use?


#17

@Ali_Arafat : can you assist me with a cfd simulation of a pump as i am new??


#18

Can you tell us what you are struggling with at the moment @klatchman?

Best,

Jousef


#19

Currently i am trying to simulate the operation of a small submersible centrifugal pump… A resun king 2 model… My problem is my simulation is not giving me close results experimental values. The pump operates at the bottom of a pond 3ft deep and the discharge pipe comes above the water level and recirculates… I dont know if i am using wrong boundary conditions or something is wrong to my model… I use solidworks flow… I need guidance please @jousefm @Ali_Arafat


#20

Currently i am trying to simulate the operation of a small submersible centrifugal pump… A resun king 2 model… My problem is my simulation is not giving me close results experimental values. The pump operates at the bottom of a pond 3ft deep and the discharge pipe comes above the water level and recirculates… I dont know if i am using wrong boundary conditions or something is wrong to my model… I use solidworks flow… I need guidance please @jousefm @Ali_Arafat