calculate optimum axial flow impeller

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Erilaz
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Joined: Mon Dec 30, 2019 10:51 am

calculate optimum axial flow impeller

Post by Erilaz »

Hello, can Freecad be used to calculate optimum impeller blade pitch, impeller diameter and required impeller blade area ?

Is it also possible to calculate optimum outlet nozzle length and smallest nozzle diameter?

It's a water jet drive for a small boat.

For the typical geometry of these things, look at those transparent green ones in the front:
https://img2.cgtrader.com/items/2874368 ... tl-dae.jpg

The values I have:

Engine power: 25KW ( 33.52 international horsepower)

Engine torque: 35 Nm

Impeller shaft rpm: 6000~9000 rpm ( say 7500 average)

liquid density: 1.025 kg/liter ( water ).

Number of impellers on the shaft: 2

Number of impeller blades per impeller: 4
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NewJoker
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Re: calculate optimum axial flow impeller

Post by NewJoker »

Since rotating regions are not yet implemented in CfdOF but the underlying open-source solver (OpenFOAM) supports them, I would advise doing the initial setup in this module, exporting the necessary solver input files, adding some lines to use a rotating region and running the analysis externally. Then you can use ParaView for postprocessing like you normally would. Check this series of tutorials, it can be helpful: https://www.youtube.com/watch?v=fdikenPo4pE
thschrader
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Re: calculate optimum axial flow impeller

Post by thschrader »

Erilaz wrote: Wed Jun 01, 2022 4:39 pm Hello, can Freecad be used to calculate optimum impeller blade pitch, impeller diameter and required impeller blade area ?
...
Maybe this tutorial is a starting point:
https://www.youtube.com/watch?v=Q10MbSFEiEM
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Raedchen_im_System
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Re: calculate optimum axial flow impeller

Post by Raedchen_im_System »

Erilaz wrote: Wed Jun 01, 2022 4:39 pm Hello, can Freecad be used to calculate optimum impeller blade pitch, impeller diameter and required impeller blade area ? Is it also possible to calculate optimum outlet nozzle length and smallest nozzle diameter?
In general, Freecad CfdOF can perform a simulation of an impeller. With a steady simulaion, you can only simulate one working condition (inlet speed of the water, revolution speed of the impeller) with one impeller design. If you want to optimize the impeller, you must perform many simulations of different designs. Probably, it makes sense to make a variation on the inlet speed of the water as well.
Maybe this tutorial is a starting point:
https://www.youtube.com/watch?v=Q10MbSFEiEM
Please note that the simulation shown in my video is a simplified approach. For example, if you want to study the interaction between the two impellers, you need to build a rotating mesh solution. However, this solution is much more complicated, the simplified approach should deliver sufficiently accurate results.
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