|
|
I believe some of the heat problems could be overcome by designing the laser to work at the engine's operating temperature, rather than at room temperature. Then you can use a Peltier cooler to just keep the laser stable at the temperature it naturally wants to be at rather than fighting the engine heat. The problem would be getting the engine, or at least the laser, properly warmed up. I wonder how long it would take for a Peltier cooler to heat a laser from 20 below up to 200 degrees?
Of course, if everything's going over fiber, you don't necessarily need as much cooling, but then you have other problems.
I think the squeegee action of the apex seals will help a lot with window fouling. They usually keep the rotor housing fairly clean in the areas where they make solid contact. Sort of like the cylinder walls in a piston engine, the rings keep them fairly clean even if the head looks like you could plant flowers in it. Whether it's enough, I can't say.
On Sat, Apr 14, 2012 at 9:39 AM, <CozyGirrrl@aol.com> wrote:
Ran this by a girlfriend who gets to play with weapon grade energy stuff,
she blew a hole through her kitchen wall with a single pulse from a homebrew
laser in college, glad she's on our side.
My greatest concern is that in the lab under ideal conditions a laser
sounds great, under the hood in the real world is another matter, at 10k ft a
serious matter.
She plays with this stuff every day, here is her reply:
/begin
Subj: Re: laser ignition
Hey there,
No, that doesn't
make a lot of sense. Not only is the window issue a serious problem that I
don't know how you would overcome. There is also an issue of heat. A
solid state laser has a really crappy mode so in order to get the fluence needed
to ignite the fuel, the laser would have to be in the near-field.
Diffraction losses past this point will not let the beam focus tight
enough to have enough energy to heat anything sufficiently for ignition.
With the laser being this close to the engine, heat becomes a serious
problem. As the lasers temperature changes, more than a couple of degrees
C, the wavelength shifts. A change of 2 degrees C can cause a solid
state (diode) laser to shift wavelength enough where it is no longer at the
proper resonance and the power drops significantly. Even with active
cooling on the laser, which would be required, the heat of the engine would
probably be greater than what a TC cooling device can handle.
A higher power
DPSS style laser could be used and launched into fiber which could solve the
heat problem but now you have the grime and combustion by-products in the engine
that would definitely foul a fiber or an optical window which would induce
diffraction and cause a fluence drop. So, I personally don't see how they
could make this work. Or even why for that matter. High voltage is
cheap and has worked well for over 100 years. /end
It's her last paragraph that concerned me the most. I spent 20 years
working with HID systems focused into fiber optics. Her last sentence says it
all.
I am not against innovation but I am very cautious.
Chrissi &
Randi
www.CozyGirrrl.com
CG
Products, Custom Aircraft Hardware
Chairwomen, Sun-N-Fun Engine Workshop
In a message dated 4/13/2012 11:38:05 A.M. Central Daylight Time,
echristley@att.net writes: CozyGirrrl@aol.com wrote:
> And all this will work only if the
combustion chamber is always squeaky
> clean, no deposits or film on the
windows, once that happens it all goes
> to heck quickly.
>
If you've got a film building up on the rotor housing's chrome face,
aren't you behind the curve already? I could see
it being a problem
in a piston cylinder's head. I've had to chip off gunk with a
screwdriver it had built up so thick.
But they aren't constantly being
wiped by an apex seal like in a rotary.
--
Homepage:
http://www.flyrotary.com/
Archive and UnSub:
http://mail.lancaironline.net:81/lists/flyrotary/List.html
|
|