My new Engine

[ganuganu]

I just came through this equation a= square root of gamma*R*T which gives us the value of velocity of sound. Here we are taking the value of gamma as 1.4 , R as 287 and Temp as eg. 400kelvin substituting in the above equation we get
a= square root of 1.4*287*400 = 400.89m/s is it true because i have some doubt in this value because for such low temperature does the velocity of sound would be so high.

And according to Rayleigh flow mach number increases by heating and decreases by cooling at subsonic speeds and mach number increases while cooling and decreases by heating at supersonic speeds. Let us consider that a pulsejet coupled with ramjet moves at a speed of mach 3(supersonic speed) in case of pulsejet there is only large amount of heat produced but less cooling can it maintain the speed. If we reduce the entropy(waste heat rejection) in CC can we attain a good amount of velocity.

[PyroJoe]

R in the equation stands for Gas Contant:
http://en.wikipedia.org/wiki/Molar_gas_constant

Wikipedia shows 343.2 meters per second for speed of sound at 20 degrees Celsius, in dry air.
http://en.wikipedia.org/wiki/Speed_of_sound

about halfway down they show the same equation.

[ganuganu]

I have the above equation in my engineering books iam not about the link. I have derived an answer using that formula "a= square root of 1.4*287*400 = 400.89m/s" is the value 400.89m/s true to our real pulsejet engine at working.

[PyroJoe]

I found 287 as a universal gas constant here at the bottom:
http://www.indiana.edu/~geog109/topics/ ... sLaws.html

All of it is hinged around 3 variables Pressure, Temperature and Density. Any change in one affects the others. About the only constant that can be realized is one of these is changing all the time in every portion of the pipe.

[ganuganu]

oh so due to the non uniformity in pulsejet engines its very hard to find i get it now.

[PyroJoe]

There was one member (milisavljevic) that had a method of analysis that would predict reasonably close. He is not participating any longer.

I recall Mike E. may have developed a good method also.

[metiz]

If you know the current situation in an engine: gas temp, R value (which btw is only 287 for air), mass in kg (just use 1), volume and pressure, you can calculate missing values using (P*V)/T=m.Rs

P=pressure in Pascal
T=temperature in Kelvin
V=volume in m3
Rs=gasconstant
m=mass in kg

[ganuganu]

Thanks metiz , one small question you said 287 for air so you say that R changes with air fuel ratio. I will try to get permission from IIT madras for testing my engine but dont know how much it will cost .

[metiz]

Yes. "Clean" air has a constant of 287. This can change if other gasses are added.

[ganuganu]

Hello joe one good news for you, engine which troubled me for long time has been successfully started kept my mobile phone in house so i was not able to take video i will post it tomorrow. I came to know about my mistake and corrected it. The main problem was with intake pipe instead of using 3.8cm dia i used 4.5cm dia. And second good news is that i planned to do Msc in aerospace engineering. Here is the pic of the engine before test run.

[PyroJoe]

Good to hear you found the problem.

[ganuganu]

Do you have any idea over the thrust of the engine, iam not able to run the engine at full throttle now because of neighbours .

[PyroJoe]

Probably between 7 to 10 pounds depending on the setup. For short a short run you may push it up or past 12 pounds with the correct fuel air mixture, but the mild steel won't last long.

[ganuganu]

Few weeks before i got this book i think this will be helpful for beginners. here is the link to download.

http://www.mediafire.com/?e12x53jfeq0vmp7

First time planned to add an conical augmenter. Any suggestions.
http://imageshack.us/photo/my-images/82 ... g1aug.png/

[PyroJoe]

Augmenter looks good, I like the slow taper in the cone. Let us know how you get along with it.