Surface radiators for water cooled engines

I mean, I think it's a dead-end idea, but I'm prepared to be
demonstrated wrong. But if you persist in just telling folks that
they're wrong without a shred of either empirical evidence or
engineering support, you're gonna stay pigeonholed in a lot of folks'
chucklehead files.

Thanks, and best regards to all

Bob K.
++++++++++++++++++++++++++++++++++++++

WoW.
Definitely time to fish or cut bait. g

P.S.
This sure is out of character for you, Bob.


Barnyard BOb --

(Bob Kuykendall) wrote in message
If you think you have a good idea, then fine, try it. Make a
prototype, test it under representative conditions, and publish your
results. If the results bear out your assertions, you will be hailed
as an insightful genius. If there are competitive advantages to your
idea, you can expect to see swift application of it to a wide variety
of heat exchange situations.

I think its too soon make that step, I'm not sure what the proportions
need to be.

Anyhow, yammering about your idea here on Usenet accomplishes less
than zero, since it takes up time that you could otherwise be using to
implement and test your idea. From the fact that you persist in
arguing about it in this forum, I can only conclude that you are more
interested in the argument that in the idea under discussion.

"Listen, I'm not here for an argument..." (Python)
I didn't come to the newsgroup to as advice. The idea was to have a 2
way discussion, I guess you could call that yammering. Sometimes in
the early stages of a development you just brain storm and bounce
ideas off different people's heads. Its a fun excercise for people
who like to think and interact. Its true, the CNC isn't chewing
aluminum and there aren't any flames yet, so it isn't quiet as
exciting, but until you think you've got the theory understood, you're
wasting time and material trying to construct something that will
likely take an inordinate amount of experimentation to optimize.
Thats the difference between an engineer and a tech I guess.

And that's a shame, since your surface radiator idea would be pretty
easy to prototype. All you need is an old pickup truck, an old car
hood, a bunch of copper tubing, a bunch of cheap plumber's solder, and
a propane torch. Oh, and a driver's license...

You need a propeller and cowl as well. The success of the idea may
hinge on the turbulence in the prop wash which decays very quickly as
you get further from the prop blade.

I mean, I think it's a dead-end idea, but I'm prepared to be
demonstrated wrong. But if you persist in just telling folks that
they're wrong without a shred of either empirical evidence or
engineering support, you're gonna stay pigeonholed in a lot of folks'
chucklehead files.

In a discussion its okay to disagree with someone as long as you can
supply a reason. The other person, can then attempt to address that
issue. This goes on and on until you've either come to the same
conclusion or some fundamental point on which there is a disagreement
which must be settled by experimental data or a more detailed off-line
analysis.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com

OK, Bob and Jay, chill out. You're both cool engineers and have a lot to
contribute. Lets just rattle the idea around a bit and see what comes out.

The skin radiator was been tried on the Schneider Cup seaplane racers in the
1930's and it worked, at least for that purpose. It probably worked much
better than the flat plate alternative seen on other aircraft from that era.
It might not have as much advantage over a highly efficient ducted radiator
like the P-51 used.

Skin radiators weren't really tried on military aircraft in WWII, at least
as far as I know, probably out of concern they would be very vulnerable to
enemy fire. After the war, people interested in performance were into jets
and not too interested in some weird pre-war radiator design even though it
might work fine.

Then there is a question of the effect of heating the boundary layer. Some
say that it will thicken and separate if the wing skin is heated. On the
other hand, some say it will have a turbulator effect and energize the
boundary layer. The Schneider Cup racers did not have laminar flow airfoils
so any effects, good or bad, might not have been noticed.

I have read a bit of work on "Hot Wing" aerodynamics and the results were
inconclusive as far as effects on the extent of laminar flow on the wing but
seemed to suggest a reduction in L/D which would be expected if the heating
disturbed the boundary layer.

It's possible, even likely, that a skin radiator would work best for cooling
and have the least negative effects on laminar flow if the surface chosen
were already subject to turbulent flow. The wing leading edge behind the
prop comes to mind.

Bill Daniels

"Jay" wrote in message
om...
(Bob Kuykendall) wrote in message
If you think you have a good idea, then fine, try it. Make a
prototype, test it under representative conditions, and publish your
results. If the results bear out your assertions, you will be hailed
as an insightful genius. If there are competitive advantages to your
idea, you can expect to see swift application of it to a wide variety
of heat exchange situations.

I think its too soon make that step, I'm not sure what the proportions
need to be.

Anyhow, yammering about your idea here on Usenet accomplishes less
than zero, since it takes up time that you could otherwise be using to
implement and test your idea. From the fact that you persist in
arguing about it in this forum, I can only conclude that you are more
interested in the argument that in the idea under discussion.

"Listen, I'm not here for an argument..." (Python)
I didn't come to the newsgroup to as advice. The idea was to have a 2
way discussion, I guess you could call that yammering. Sometimes in
the early stages of a development you just brain storm and bounce
ideas off different people's heads. Its a fun excercise for people
who like to think and interact. Its true, the CNC isn't chewing
aluminum and there aren't any flames yet, so it isn't quiet as
exciting, but until you think you've got the theory understood, you're
wasting time and material trying to construct something that will
likely take an inordinate amount of experimentation to optimize.
Thats the difference between an engineer and a tech I guess.

And that's a shame, since your surface radiator idea would be pretty
easy to prototype. All you need is an old pickup truck, an old car
hood, a bunch of copper tubing, a bunch of cheap plumber's solder, and
a propane torch. Oh, and a driver's license...

You need a propeller and cowl as well. The success of the idea may
hinge on the turbulence in the prop wash which decays very quickly as
you get further from the prop blade.

I mean, I think it's a dead-end idea, but I'm prepared to be
demonstrated wrong. But if you persist in just telling folks that
they're wrong without a shred of either empirical evidence or
engineering support, you're gonna stay pigeonholed in a lot of folks'
chucklehead files.

In a discussion its okay to disagree with someone as long as you can
supply a reason. The other person, can then attempt to address that
issue. This goes on and on until you've either come to the same
conclusion or some fundamental point on which there is a disagreement
which must be settled by experimental data or a more detailed off-line
analysis.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com

This gets very boring. How about going back flying.
Cheers
"Morgans" jisumorgan@charterdotjunkdotnet a écrit dans le message news:
...

"Barnyard BOb --" wrote in message


Barnyard BOb -- Have sharp stick. Will travel.

Be careful not to poke your eye out! g
--
Jim in NC

"Jean-Paul Roy" wrote:

This gets very boring. How about going back flying.
Cheers
++++++++++++++++++++++++++++++++

How about you just crawl back in
your net cop hole and **** off?

May I suggest...
If you don't like what you read, don't read it.
Not my job to step aside to satisfy your whims.

I place no restrictions upon your speech. Therefore, please
do not **** with my rights in this unmoderated group.

Cheers to you, poor misguided soul.


Barnyard BOb

B-yard S.O.B a (man?) with a kind soul and of good manners
has spoken. Maybe Jean-Paul was just exercising his right
to put forward his opinion (a god one at that).

ower


"Barnyard BOb --" skrev i meddelandet
...


"Jean-Paul Roy" wrote:

This gets very boring. How about going back flying.
Cheers
++++++++++++++++++++++++++++++++

How about you just crawl back in
your net cop hole and **** off?

May I suggest...
If you don't like what you read, don't read it.
Not my job to step aside to satisfy your whims.

I place no restrictions upon your speech. Therefore, please
do not **** with my rights in this unmoderated group.

Cheers to you, poor misguided soul.


Barnyard BOb

At zero airspeed doesn't really matter what the heat transfer
capabilities are. During operation you'd like it to be the exact same
temperature as the coolant, this will ensure maximum transfer.

(Bob Kuykendall) wrote in message . com...
Earlier, (Jay) wrote:

...And of course in big red letters
"HOT SURFACE- DO NOT TOUCH"...

Well, if it stays hot, it isn't a very good heat exchanger, is it?

Bob K.

Thats a great idea and I think the construction you've described is
close to what I'd imagined too. I'm not sure the test is equivalent
to the operating environment its intended for though. On climb out,
while the IAS may be 60-70MPH, the prop wash is a much higher speed.
Also, the prop wash is much more turbulent than the clean air on the
front of your wifes car, and that has a dramtic effect on the cooling
capability of that air. As I'd mentioned before, a smooth air flow
tends to build up a layer of warm air along the boundary that impeds
heat flow. Where in the turbulent case "new" cool air keeps coming in
contact with the hot aluminum.

Regards

On climb out Ernest Christley wrote in message .com...
Jay wrote:

You might argue that the heat transfer for that area isn't sufficient,
and I think the analysis needs to be done, but not by a direct
comparison of area from an automobile finned type radiator. The
conditions are just too different to make that meaningful. A bottom
up calculation that includes heat transfer effects of turbulent air,
heat transfer properties of materials (likely Aluminum), waste heat
from engine, etc.

So do it. Take a couple of 2'x2' sheat of .035 aluminum and a few
strips of 3/8" flat aluminum. Lay the flat strips on one piece of sheet
so that it forms sides and an interior maze that the water will have
to flow through. Drill, caulk and rivet it together. Add a spout for
the water to go in and come out with temp probes at each one. Add a
couple of T joints to the plumbing of your wife's car (don't let her
catch you at it) and bolt the thing to the hood in a way that will
shield one side (the one that will be inside the cowl) and also simulate
the AOA of the cowl bottom on climbout.

Drive around a while at 60 to 70mph and then report back here with what
you find out.

Hi Bill,

Thanks for joining the fray.

At first I was also thinking the wing location for the radiator made a
lot of sense, but then thinking about the complexity of installation
caused me to reconsider. And along the way I found that the turbulent
characteristic of air adds greatly to its heat transfer
characteristics. Since turbulence drops exponentally with distance,
putting the heat transfer surface on the cowl near to the propeller
made more and more sense. That location allows people to go with the
"firewall forward" type of thinking and keep radiator hoses short.

As far as the aerodynamic effects, I hadn't figured there would be too
much effect because of the amount of heat added to this huge volume of
air. I guess it would make the air slightly less dense around the
fusalage and back dispating as the boundary air mixes with more of the
air mass.

p.s. What you were refering to a "flat plate" is really the
traditional blow through type radiator see on autos and other low
speed vehicles. Right?


"Bill Daniels" wrote in message ...
OK, Bob and Jay, chill out. You're both cool engineers and have a lot to
contribute. Lets just rattle the idea around a bit and see what comes out.

The skin radiator was been tried on the Schneider Cup seaplane racers in the
1930's and it worked, at least for that purpose. It probably worked much
better than the flat plate alternative seen on other aircraft from that era.
It might not have as much advantage over a highly efficient ducted radiator
like the P-51 used.

Skin radiators weren't really tried on military aircraft in WWII, at least
as far as I know, probably out of concern they would be very vulnerable to
enemy fire. After the war, people interested in performance were into jets
and not too interested in some weird pre-war radiator design even though it
might work fine.

Then there is a question of the effect of heating the boundary layer. Some
say that it will thicken and separate if the wing skin is heated. On the
other hand, some say it will have a turbulator effect and energize the
boundary layer. The Schneider Cup racers did not have laminar flow airfoils
so any effects, good or bad, might not have been noticed.

I have read a bit of work on "Hot Wing" aerodynamics and the results were
inconclusive as far as effects on the extent of laminar flow on the wing but
seemed to suggest a reduction in L/D which would be expected if the heating
disturbed the boundary layer.

It's possible, even likely, that a skin radiator would work best for cooling
and have the least negative effects on laminar flow if the surface chosen
were already subject to turbulent flow. The wing leading edge behind the
prop comes to mind.

Bill Daniels

Hi Jay,

Yes, the "flat plate" refers to an automotive-like placement of the
radiator.

I suspect that the skin radiator might need a much larger area than a
honeycomb type heat exchanger in a duct since the stagnant boundary layer on
a cowling would limit heat transfer to the free-stream flow. The area
available on a cowling might not be enough either.

I would be very suspicious of calculations comparing the heat transfer
efficiency of skin vs. honeycomb radiators. This is an area were
experimental data is needed.

Another area where I would like to see some experimental data is the
"Radiator Ramjet" (just to pick a controversial term) where the radiator is
in a tube and the heated air exits the rear of the tube at a higher velocity
than the cool air entering the front of the tube, theoretically producing a
small amount of thrust that offsets the drag of the radiator.

Bill Daniels
"Jay" wrote in message
om...
Hi Bill,

Thanks for joining the fray.

At first I was also thinking the wing location for the radiator made a
lot of sense, but then thinking about the complexity of installation
caused me to reconsider. And along the way I found that the turbulent
characteristic of air adds greatly to its heat transfer
characteristics. Since turbulence drops exponentally with distance,
putting the heat transfer surface on the cowl near to the propeller
made more and more sense. That location allows people to go with the
"firewall forward" type of thinking and keep radiator hoses short.

As far as the aerodynamic effects, I hadn't figured there would be too
much effect because of the amount of heat added to this huge volume of
air. I guess it would make the air slightly less dense around the
fusalage and back dispating as the boundary air mixes with more of the
air mass.

p.s. What you were refering to a "flat plate" is really the
traditional blow through type radiator see on autos and other low
speed vehicles. Right?


"Bill Daniels" wrote in message
...
The skin radiator was been tried on the Schneider Cup seaplane racers in
the
1930's and it worked, at least for that purpose. It probably worked
much
better than the flat plate alternative seen on other aircraft from that
era.
It might not have as much advantage over a highly efficient ducted
radiator
like the P-51 used.

Skin radiators weren't really tried on military aircraft in WWII, at
least
as far as I know, probably out of concern they would be very vulnerable
to
enemy fire. After the war, people interested in performance were into
jets
and not too interested in some weird pre-war radiator design even though
it
might work fine.

Then there is a question of the effect of heating the boundary layer.
Some
say that it will thicken and separate if the wing skin is heated. On
the
other hand, some say it will have a turbulator effect and energize the
boundary layer. The Schneider Cup racers did not have laminar flow
airfoils
so any effects, good or bad, might not have been noticed.

I have read a bit of work on "Hot Wing" aerodynamics and the results
were
inconclusive as far as effects on the extent of laminar flow on the wing
but
seemed to suggest a reduction in L/D which would be expected if the
heating
disturbed the boundary layer.

It's possible, even likely, that a skin radiator would work best for
cooling
and have the least negative effects on laminar flow if the surface
chosen
were already subject to turbulent flow. The wing leading edge behind
the
prop comes to mind.

Bill Daniels