Pulse Jet Compression

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pulseduino
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Pulse Jet Compression

Post by pulseduino » Sat Jul 02, 2016 3:33 am

Assume there was a pulse jet that had a chamber which compressed air/fuel near the compression ratios of car engines

1. Would it be more "efficient" than turbo prop engines? (uses less fuel to produce the same thrust)

2. What kind of temperatures are we looking at internally? (Mild steel turns mild red around 1320F- 1610F?)

3. How many decibels would this engine produce?

4. What dimensions are we looking at to achieve a low Hz engine of this nature?

Rocket Man
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Re: Pulse Jet Compression

Post by Rocket Man » Fri Aug 19, 2016 1:06 am

1. Pulse jets are not efficient.

2. Temperature is from about 1400 F on propane, gas, or kerosene but can be higher on other fuels.

3. Db = LOUD over 150 Db.

4. Low Hz. the German V1 was about 40 Hz. My Argus PJ-20 it about 200 Hz. You can determine the Hz here, http://hyperphysics.phy-astr.gsu.edu/hb ... pecol.html

I don't think many people are on this forum these days no one will answer questions. I have not been here for a year no one else is here.

metiz
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Re: Pulse Jet Compression

Post by metiz » Fri Aug 19, 2016 9:43 am

I'm still here! :P
Quantify the world.

tufty
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Re: Pulse Jet Compression

Post by tufty » Sat Aug 20, 2016 6:12 am

No, I'm spartacus!

For the questions:

1 - Maybe, maybe not. How long is a piece of string?
2 - When steel goes yellow it's >1000°C, and that's without taking into account boudary layer cooling
3 - Compression is not necessarily directly related to SPL. "Bloody loud", like all pulsejets.
4 - Frequency is related to size, you'd have to specify "low frequency". "Quite big" would be my answer.

pulseduino
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Re: Pulse Jet Compression

Post by pulseduino » Fri Oct 14, 2016 6:57 pm

Rocket Man wrote:1. Pulse jets are not efficient.

2. Temperature is from about 1400 F on propane, gas, or kerosene but can be higher on other fuels.

3. Db = LOUD over 150 Db.

4. Low Hz. the German V1 was about 40 Hz. My Argus PJ-20 it about 200 Hz. You can determine the Hz here, http://hyperphysics.phy-astr.gsu.edu/hb ... pecol.html

I don't think many people are on this forum these days no one will answer questions. I have not been here for a year no one else is here.

They are not efficient but let's just assume they could compress an air/fuel mixture near the compression ratios of cars.

Would they be more efficient than a prop engine?

metiz
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Re: Pulse Jet Compression

Post by metiz » Fri Oct 14, 2016 10:58 pm

Easily. No moving parts to waste energy on
Quantify the world.

nitro
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Re: Pulse Jet Compression

Post by nitro » Thu Nov 03, 2016 1:12 pm

Just turn a Turbine Jet into a PJ .The power &fuel efficiency all get better.Superchargers & N02 gas was tried on PJ engines many years ago .Both work. Noise is a problem & vibration damage another.The combustion chamber must be different to a turbine jet because of the shock waves.Reed valves are still a problem unsolved also.A PJ does need more compression but how to do it.Rotary Valves may be one way to help but there rotation needs to be controlled by each explosion.With a spinning valve you will now have that Gyro effect in a fast turn on a plane.Titanium would be the choise metal I guess as its super light. Some have tried to have two PJ engine run together out of tune to each other.When one goes bang the pressure is used to compress the air fuel mix in the other.I dont think any worked but the theory was there.

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