[Robotgroup] water flow

[Leslie Filip]

If the blades are in a blower-type arrangement instead of a fan-like  
arrangement it would chop the water more smoothly. The nozzle would  
have to be shooting from within the cage though.

Les


On 10 Aug 2006, at 2:53 AM, Leslie Filip wrote:

> Gray,
>
> I believe it is still laminar flow you are wanting, only that instead
> of constant streams you want blobs. In order to accomplish this the
> material has to have a ramp up of speed inside the laminar flow tube
> before it exits. In the examples I have seen, it was not possible to
> have a series of closely spaced blobs using only control valves.
> There may be a solution.
>
> If you have an arc of laminar flow water, I believe you could
> mechanically chop it into blobs, removing the water where you want
> space. Think of the way a jet engine's blades are tilted. As the
> water passed through rotating blades the entry point and exit point
> of the blades in the water column would coincide with the forward
> motion of the water arc, thus chopping it into a series of small
> cylinders. Then through surface tension, each cylinder would reshape
> itself into blobs. It is the lack of uncontrolled angular momentum
> that allows the blob to remain a blob.
>
> There is a limit to the speed at which the water can travel as a
> blob, however. When the speed goes beyond a certain point, the air
> pressure at the front of the blob destabilizes it. In a parabolic
> arc, this is as true for the speed at which the water exits the
> nozzle as it is for the descent.
>
> The arcs I saw in Las Vegas in some of the smaller water gardens went
> about 10-12 feet without a problem. The arcs are more prone to
> destabilization than blobs due to surface tension and the differing
> speed from one part of the column to another. I don't think there
> would be any problem at all with blobs remaining blobs over this
> distance.
>
> Les
>
>
> On 09 Aug 2006, at 5:26 PM, Gray Mack wrote:
>
>> What I am looking for is a term for creating liquid
>> blobs. How big they can be and stuff based on driping
>> from a drop tower or launched.
>>
>> Another approach- Put some LED's, a microcontroller, a
>> capacitor, and an inductor+rectifier into a bunch of
>> ping pong balls. Fire them from an air blower/cannon
>> at synchronized intervals in an arch or straight down
>> or through a clear pipe and when they land they roll
>> to a hopper to be recycled. As they are loaded into
>> the cannon the capacitor is charged through the
>> inductor via a varying magnetic field at the cannon
>> and instructions on when to light up are also sent
>> through the field to each ball. The capacitor has
>> enough power to blink LEDs a few times during its
>> travel as directed by the cannon.
>> -Gray
>>
>> --- Shane Geiger <sgeiger at ncee.net> wrote:
>>
>>> FYI:  http://en.wikipedia.org/wiki/Laminar_flow
>>>
>>>
>>>
>>>
>>> Paul Atkinson wrote:
>>>> Gray,
>>>>
>>>>   I don't think you'll have a problem if you
>>> aren't susceptible to jitter between pulses (as
>>> stepper motors are.)
>>>>
>>>>   You may have to have a special driver (giveio)
>>> or something like that to access the parallel port
>>> under Win XP/NT/2k if memory serves.
>>>>
>>>>   The opposite of laminar flow is turbulent flow.
>>>>
>>>>   Paul
>>
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