Almost 2 years back, I thought of writing this blog. Wrote it and even created a video, however the blog never got published. Though the video remained on YouTube. To my surprise, the video has almost 48,000 hits. It appears this application of SOLIDWORKS Flow Simulation is indeed bringing a lot of value hence why I decided to write this blog again but with a better video.
Typical requirements of Suction Pump Designer will be to design the product for a certain amount of Suction pressure and Flow rate. Other parameters like head created, efficiency, torque on the impeller etc are as well relevant.
The historical process is to do manual calculation, create a prototype and then check if it works as expected. If not then modify the Design -> Prototype -> Test…. And this loop continues. It is obvious that this is time consuming and expensive. Even after multiple iterations, one may not get the best outcome.
This similar process can be done virtually using a software and only one final prototype might be required to ensure that it is all as expected. So, how do we do it virtually?
This first thing in the process would be to model the product in detail as per the design requirements. Here is an example:
This complete product needs Structural Simulation as well, however in this blog, I am concentrating on the most important flow parameters – Suction pressure and Flow Rate.
As a first step, we need to simplify the above structure and keep entities that are necessary for SOLIDWORKS Flow Simulation. We can get rid of a few entities which can help in simplifying the setup without harming the flow region. Normally, bolt holes, bolts, keyways etc can be suppressed. There is also a need to add a few extra pipes at the inlet and outlet to help stabilize the flow for calculation. We also need a closed volume for representation of fluid and that is achieved by creating lids at the open end of pipes. The CAD model is now ready for Simulation.
The below model shows a refined and ready model for analysis.
Now let’s start with Flow Simulation, the steps would include: –
- Create the initial global settings.
- Representation of the rotating region.
- Applying the boundary conditions.
- Results interpretation.
- Create the initial global settings,
In SOLIDWORKS, go to Flow Simulation-> Wizard, Follow the steps through it, it gives options to select the Fluid, activate necessary options like Rotating region, select the appropriate units etc…. The video down here has more details…
- Representation of the rotating region, see the below image, we have to create a component that is encompassing the rotating component and to be specific the Impeller blades
Flow Simulation uses this rotating component to Simulate the rotating effect. It is a simulation where in the blades are static and the fluid around it is considered to be rotating. It is a kind of relative motion. And because of blades the effect of impeller is created. This component is used for applying the rotating region boundary condition only and it is actually suppressed
There on we can apply the Rotating region boundary condition to this dummy component, the option is present under Flow Simulation-> Insert ->Rotating Region, see the below image
- Applying the Boundary Conditions
Both the inlet and outlet are set at atmospheric pressure, this can be done by Right Mouse button clicking on the Boundary conditions option and select the inner surfaces of the lids.
That’s it the model is ready to be solved. The only other thing that one needs to consider is the quality of mesh and the important goals that one wants to ensure convergence.
Results interpretation: – I would like to delve a bit more on it as it needs careful attention. As discussed above in this case we will concentrate on Suction Pressure and Volume Flow rate.
- Volume Flow Rate: – This can extracted at one of the inlet/outlets or any other location where the practical measurements are done. If results are compared with practical results be aware on how and where are they measured in practical condition. Especially, if the fluid is compressible. The volume flow rate value can be calculated from velocity or got directly from the goals.
- Suction Pressure. We need to understand that if it is a discussion on Suction pressure then it will be a pressure below atmospheric pressures. This negative pressure will help in pulling the air or any other application where this pump will be used. We can get a Cut plot of the Pressure at appropriate location to understand on how this pressure varies.
In conclusion, we saw how we can simulate a Suction pump and understand the Suction Pressure/Volume Flow rate. Knowing this, if it is not as per the expected design parameters then we can do relevant design changes to get the expected values.
The below video shows the process that has been discussed above.