A centrifugal pump is a rotodynamic pump that uses a rotating impeller.
About this creation
Pump of this type is known to me. Since impeller of centrifugal pump is a
specific shape, lego has really little to offer.
But I had some older type gears, red g9, blue g15 and yellow g21
( Technic gear Expert Builder xx Tooth with axle hole ).
So I just gave a try with these and they did throw water around.
I built a casing around two g15 gears, some piping and an electric motor to power it.
First tests show that it does work, but I got water all around table!!
Lego bricks have some 0,1mm gaps and that is enough for water to leak.
First protos leaked as much they pumped! The secret is to use fewer and bigger bricks
to minimize gaps. And tape to cover some worst leaks.
First protos had impeller in vertical position, but it wasn't a good idea.
I turned it to horizontal position, so pump can stand in the water and leaking is
no problem anymore.
I used an old 9V motor type ( 2838c01 ) because it can rotate fast enough. I had to gear it a little bit down to get more torque and thus more pumping power. The Current
version can pump to the height of 11 bricks about 4 litres/minute. It pumps water
up to 20 brick height, but max practical height is about 15.
By adding a second motor it gets more power but gears make it noisy.
With this you can make a realistic lego river/waterfall ;)
Water lubricated gears, that little pneumatic hose feeds water back
Water intake. Could be bigger, still searching the best shape.
Pump inside. The gears simply throws water down right to discharge pipe
Twin-motor test. It rews faster, but pumps only a little bit more. Probably discharge pipe should be also wider and intake too. The Train speed regulator I use has 6 speeds
and 5. speed gives already full flow.
Another twin-motor test. Original motor + direct drive motor.
But,I discovered that water intake was a problem. There is only 1 brick distance from
pump intake to the bottom. I increased it to 2 bricks and it doubled the flow !!
This one pumps to height of 21 bricks 2,6 liters/min !!
I retested the original pump and now it pumps 4,5 liters/min !!
Tuning this pump is an endless job ;)
A LDD-picture of another pump model.
This model uses 21-tooth gears. chamber is made of 2339 and 30099 bricks and it's
perfectly round. Gap between gears and chamber is about 2mm, should be very tight.
Not tested in real life yet, but I expect this to be very good pump.
First Test: about 4,5L/min to height of 14 bricks !! intake may still be too small.
But these panels, 2 x 2, are leaking terribly, so i have to use tape ;)
Pump model with XL-motor, lot of changes since first proto. Pumps 6,5 liters/min.
And in real life, pumping 6,5 liters/min ( This has now separate page + video )