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(Joe) #1

Hi everyone! Welcome to our product support page. If you have questions about any BlueRobotics products please post them here where they can be answered by one of us here at BR or by anyone else in the community.

Happy Thrusting,

Joe


(Ion) #2

Hi Joe:

Congratuations for your very nice thrusters.

I have a question … May I know what are the nominal pitch and maximum RPM of your thruster propellers ? That’s a key data for starting some design calculations.

Kind regards and congratulations again.


(Rusty) #3

Hey Ion,

The propellers have a nominal 2 in/rev pitch (15 deg at 0.75*radius). The T100 RPM is normally around 4200 max, but can go higher at higher voltages.

What are you calculating?

Best,

Rusty


(Ion) #4

Hi Rusty:

I’m into the hydrodynamic side of Ships design. In the ROVs world I’m into the same things.

Now, checking the ROV/Propellers interaction and propulsive optimization.

As almost all ROVs are designed for low speed (box shaped), wake field is mostly neglected, but in some cases the wake factor achives values rounding 0.95, (wf>0.3 is considered too high) that, from any point of view, is an energy waist. Propellers, regardless how fine and good could be, must work into such a “dirty” flow, that nominal and real performances have nothing to do.

In the attached pic, there is a ROV’s real wake field chart at the propeller disc plane(Excel bubble chart: Circle size-> flow speed: Resolution 0.5 mm³). A tidy “good” wake field would be drawn as an almost homogeneous circles cloud, where each one size would have to be almost the same.

As it can be seen, flow is heavily untidy, and at any places, flow direction is reversed (filled blue circles).

 

Im into the study of this effect and into the research for a simple solution, while holding size, manouverability and robustness of ROVS.

Thats not a matter of going faster, but a matter of energy optimization.

 

Thanks for your answer.

Kind regards

 



(Rusty) #5

Ion,

That’s really interesting. Does the wake factor represent the turbulence of the flow? How does the suction of the nozzle effect this? Does the wake approaching the propeller smooth out?

In general, our thrust measurements are almost completely unaffected by things in front of the thruster. For instance, placing your hand 2" in front of the thruster has no effect on thrust. I would be interesting to see if this still applies once the vehicle is in motion.

Rusty