<snip>
I totally agree! 27% efficiency is poor. However I don't think any
shade tree mechanic is going to stumble on a 10% efficiency gain let
alone
an impossible order of magnitude claimed by some of these charlatans
selling miracle electric water pumps. Can we say perpetual motion?
Here is a pic of an injected molded impeller out of a Mazda V6 piston
engine. Unfortunately as you can see it failed.
Paul Lamar
I can't believe that they tried to use a plastic part! This is a
terrible
application for plastic. Hot antifreeze with who knows what type of
additives, both factory and aftermarket. Most plastics are very
sensitive to
chemical embrittlement from any type of organic solvent. Heat of course
makes it worse! All I can say is......... Bean Counters.
No, a shade tree mechanic will not stumble on meaningful gains. Like I
said
you have to use a dyno and a lot of experimentation to get anywhere.
Also
there are some significant tradeoffs for gains in efficiency. Your
operating
range may decrease. You may get increased chance of cavitation off
design
point. To increase the efficiency the cutoff is typically decreased. If
you
decrease it too far, you get a lot of noise. In a liquid this can cause
local cavitation and also fatigue the impeller. Another possible mode of
failure for your broken pump. The best approach for us is probably to
polish
the impeller, remove any casting flash on the housing. Then optimize the
pump operating point for cruise or climb (which ever turns out to be the
critical case) using different dia pulleys. You can do this using the
pump
curves that Bill is generating if you had some power consumption data.
If you will notice at any museum that has modern rocket parts on
display,
the only part of the pump you are allowed to see is the turbine. Which
is
usually a 1 or 2 stage reaction turbine. Easily designed using hand
calcs.
You will not see the compressors which use radial outflow or mixed flow
impellers on display. A lot of test time and effort goes into designing
these pump impellers and the companies involved are rather sensitive as
to
who sees them. Although not a rocket pump, I'm sure that Mazda has put a
lot
of time into designing the pump and working out the bugs. Putting the
hardware on an airplane untested is not a really good idea. Try it in a
car
first.
As to charlatans and claims. I have seen products where the
manufacturer
actually decreases the efficiency of an electric motor in order to be
able
to claim they have a 12 amp product, when 3 would do the job. But the
marketing people want to claim they have the most powerful product on
the
market. Typically done with power tools and home appliances. Nothing
surprises me anymore. The ignorance of the general public about
technology
permits many abuses.
Monty
3 amps at 12 volts.. 36 watts... .048 HP 80% motor eff. .... .038 HP
is not going to pump very much against any head even in the very very
VERY unlikely (NEAR impossible) event someone came up with a 100%
efficient centrifugal pump. 27% is
more typical and that means only
0.01 mechanical HP is available at the pump shaft to actually pump water.
Several orders of magnitude less than what is actually required to cool
a high power engine.
I don't know why people have so
much trouble understanding this. Electrical .. mechanical never
the twain shall meet.
Paul Lamar
Paul,
Perhaps we are on a different wavelength here. I was not remotely suggesting
that 3 amps at twelve volts would power a water pump on an engine. Any moron
who didn't sleep through high school physics could tell you that. I was
referring to false claims made by appliance manufacturers to illustrate a
point that it is a wider problem, not just the electric water pump snake oil
sales people. Probably 90% of all the advertising copy you read is pure
horse pucky. Performance auto aftermarket parts seem to be especially bad.
Fuel ionizers that align the fuel molecules so they burn better, all kinds
of secret formula miracle products etc, etc, etc.
Caveat Emptor
Monty
I was dumbfounded when you mentioned it in the same paragraph. I expected
you knew better. I am paranoid about electric water pumps because
I keep hearing over and over, much to my chagrin, from people taken
in by the concept. Apparently there is some know nothing articulate
person out there pushing the concept. I learned a long time ago that
articulate does not necessarily equal real knowledge. More often than
not the opposite is true.
Paul Lamar
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