Determining the Dimensions of a Pulse Jet Engine: A Scientific Approach

In summary, designing a pulse jet engine involves determining the fuel burn rates, area of the air intake valve system, and overall length and design of the engine. The burn rate of the fuel is an important factor and can be researched by looking up information on different fuel air mixtures. Additionally, the website http://www.pulse-jets.com/ provides a wealth of information on pulse jet design, but it is important to do your own research and not solely rely on others' plans. It is also helpful to have knowledge of fluid mechanics and physics, and to keep in mind that formulas and calculations may vary for different size engines and fuels.
  • #1
gary350
253
52
If you were to design a pulse jet engine where would you start?

How do you determine the diameter and length of the tail pipe?

How do you determine the diameter and length of the combustion chamber?

How do you determine the area of the air intake valve system?

How do you determine the burn rate of the fuel?

How do you determine the over all length and design of the engine?
 
Engineering news on Phys.org
  • #2
I suppose I would start with fuel burn rates. That's because, as a private citizen, I have access to a very limted number of fuels, and can easily look up their burn rates at different mixtures. From there I could determine the area of the air intake, which would tell me how large thje valve assembly needs to be, and keep going from there.
 
  • #3
Where do I look up the burn rate of fuel air mixtures?

How about a 35 lb thrust pulse jet engine with gasoline as the fuel.

Give me an example for calculating, doing all the math for this engine. If I can see an example and know where to find all the information then I can take it from there and do the math for other size engines. I would also like to use Alcohol as a fuel too. Methal or Ethyl.
 
  • #4
If you Google pulse jets, you will find a wealth of information. They are not difficult to design. However, having someone tell you how to do something doesn't teach you anything about it. You need to do the research and the digging.

How about starting here:
http://www.pulse-jets.com/
 
  • #5
FredGarvin said:
If you Google pulse jets, you will find a wealth of information. They are not difficult to design. However, having someone tell you how to do something doesn't teach you anything about it. You need to do the research and the digging.

How about starting here:
http://www.pulse-jets.com/

This information is worthless. I found this years ago. It is a bunch of plans other people have built. There is nothing her that teaches a person how to design their own. Anyone can copy other peoples plans. What I need is some scientific informations based on the laws of physics and formulas.
 
Last edited:
  • #6
gary350 said:
This information is worthless. I found this years ago. It is a bunch of plans other people have built. There is nothing her that teaches a person how to design their own. Anyone can copy other peoples plans.

If you found this site years ago and still do not know anything about pluse jets, I have to draw the conclusion your a bit lazy.:rolleyes:
 
  • #7
RonL said:
If you found this site years ago and still do not know anything about pluse jets, I have to draw the conclusion your a bit lazy.:rolleyes:

There are lots of plans there that is all I have found. Most of those plans are not good. They don't have all the dimensions and some dimensions are just numbers like 75, 40, 30, 25. So what is that, 75 what? 75 meters, 75 feet, 75 inches, 75 milimeters?

I have built a lot of pulse jet engines over the past 31 years. I have come up with my own formulas that work very well but I thing there has to be some physics involved here that can be used to design these engines and fine tune them to run at maximum efficiency.

I have book on Liquid fuel rocket engines they are all designed around the burn rate of the fuel. I think a pulse jet engine should be designed around the burn rate of the fuel but there is no data for burn rate in air.

I have been out of college 40 years, if you don't use it you loose it, I have forgotten more than I every knew. I wish I still have my old college fluid mechanics book seems to be there is some good information in there that I need.
 
  • #8
gary350 said:
There are lots of plans there that is all I have found. Most of those plans are not good. They don't have all the dimensions and some dimensions are just numbers like 75, 40, 30, 25. So what is that, 75 what? 75 meters, 75 feet, 75 inches, 75 milimeters?

I have built a lot of pulse jet engines over the past 31 years. I have come up with my own formulas that work very well but I thing there has to be some physics involved here that can be used to design these engines and fine tune them to run at maximum efficiency.

I have book on Liquid fuel rocket engines they are all designed around the burn rate of the fuel. I think a pulse jet engine should be designed around the burn rate of the fuel but there is no data for burn rate in air.

I have been out of college 40 years, if you don't use it you loose it, I have forgotten more than I every knew. I wish I still have my old college fluid mechanics book seems to be there is some good information in there that I need.

I only meant to be a little offensive in my comment, as Fred is a much respected member of this forum, you'll learn more about him and others that can help you, if you stay around awhile.
Please do, it sounds as if you have some info that can be of help to others.

I have to go for now but will be back later.

Check out the rules and forum guidelines, and stick around long enough to get to know a few of the people here.

RonL
 

1. What is a pulse jet engine?

A pulse jet engine is a type of jet engine that operates by creating a series of rapid combustion events or pulses. These pulses are created by igniting a fuel-air mixture in a combustion chamber, which then expands and creates thrust.

2. What are the main components of a pulse jet engine?

The main components of a pulse jet engine include a fuel inlet, a combustion chamber, an exhaust nozzle, and a valve or valveless system to control the flow of air and fuel.

3. How does a pulse jet engine work?

A pulse jet engine works by taking in air through the fuel inlet, which then mixes with fuel in the combustion chamber. The fuel-air mixture is ignited and creates a rapid burst of combustion, which then expands and exits through the exhaust nozzle, creating thrust. This process repeats in a cycle to continuously produce thrust.

4. What are the advantages of a pulse jet engine?

Some advantages of a pulse jet engine include its simplicity, low cost, and high thrust-to-weight ratio. It also does not have any moving parts, making it more reliable and easier to maintain.

5. What are the limitations of a pulse jet engine?

One limitation of a pulse jet engine is its inefficiency at low speeds and altitudes. It also produces a loud noise and can create a large amount of heat, making it unsuitable for use in certain applications. Additionally, the design and construction of a pulse jet engine can be complex and require specialized knowledge and materials.

Similar threads

Can a Railgun-Powered Ramjet Solve the Challenges of High-Speed Travel?
    • General Engineering
Replies
4
Views
2K
As much steam as possible from engine exhaust gas + warm water?
    • General Engineering
Replies
25
Views
2K
Measurement of actual CO2 mass emitted from a diesel engine
    • General Engineering
Replies
5
Views
2K
Help needed to design a pulse jet engine.
    • General Engineering
Replies
4
Views
13K
I Understanding the thrust generated by a typical jet engine
    • Mechanics
Replies
2
Views
1K
Calculate Frequency of Flat Spring Steel for Reed Valves in a Pulse Jet Engine
    • Mechanics
Replies
26
Views
3K
Expansion ratio of burned Fuel
    • General Engineering
Replies
4
Views
21K
Optimization of barrel length in pneumatic cannons
    • General Engineering
Replies
23
Views
2K
I What Causes Jets to Entrain Mass?
    • Other Physics Topics
Replies
4
Views
1K
Pulse Jet engine - A new design concept
    • General Engineering
2
Replies
43
Views
24K

Hot Threads

Recent Insights

Back
Top