Search found 539 matches

by skyfrog
Sun Jul 25, 2004 1:08 pm
Forum: Valved pulsejet forum
Topic: Thermal efficiency calculation?
Replies: 46
Views: 24711

Let me add one more fact, the combustion process for pulsejet isn't really within the so called combustion chamber, the fuel-air mixture is populated all over the tailpipe, and, when burning, the flame frontal actually moves from one end (inside) of the tube to the other (outside). Since the heating...
by skyfrog
Sun Jul 25, 2004 12:35 pm
Forum: Valved pulsejet forum
Topic: Thermal efficiency calculation?
Replies: 46
Views: 24711

The one and only advantage of the pulsejet over the turbojet is precisely that it is a pressure gain combustor, meaning that combustion is under constant volume. Otto cycle is no doubt constant volume due to the cylinder movement is neglectably small during detonation, but for pulse jet what we hav...
by skyfrog
Sun Jul 25, 2004 12:09 pm
Forum: Valved pulsejet forum
Topic: Thermal efficiency calculation?
Replies: 46
Views: 24711

Why do you think it's Brayton cycle? Well, it sure looks like, but frankly I'm not quite sure if this deviate too much from reality or not. In order to analyze, assuming : 1. the combustion and heat-dissipation processes are under constant pressure, 2. the compression and expansion processes are is...
by skyfrog
Sun Jul 25, 2004 6:24 am
Forum: Valved pulsejet forum
Topic: Thermal efficiency calculation?
Replies: 46
Views: 24711

my calculation is thermal efficiency = 52% for compression ratio=1.2, specific heat ratio = 1.33, Am I too optimistic ?
by skyfrog
Sun Jul 25, 2004 6:02 am
Forum: Valved pulsejet forum
Topic: Pulsejet calculators
Replies: 9
Views: 7045

The diamter of the combustion chamber is not equal to its lenght. It is goverened by the dimensions of the valve system you make. Three recomended dimensions are given as the variable G. 1 each for the different types of valve systems (petal valve, high efficiency petal valve, and valve grid) Gee t...
by skyfrog
Sun Jul 25, 2004 5:35 am
Forum: Valved pulsejet forum
Topic: Thermal efficiency calculation?
Replies: 46
Views: 24711

Thermal efficiency calculation?

The process of a pulsejet looks like a Brayton cycle, does anyone have materials regarding the calculation of the thermal efficiency ?

This topic shouldn't be too new, if it's available, I'd like to have a look of it, rather than do it by myself.
by skyfrog
Sun Jul 25, 2004 5:05 am
Forum: Tools and Construction
Topic: Dynajet valveless conversion and Pulsejet calculator 1.5
Replies: 9
Views: 5521

Re: Dynajet valveless conversion and Pulsejet calculator 1.5

Eric wrote:Anything else anyone wants to see added?
It would be nice to have the total weight estimation. Sorry if it already have.
by skyfrog
Sat Jul 24, 2004 3:36 pm
Forum: Valved pulsejet forum
Topic: Pulsejet calculators
Replies: 9
Views: 7045

5kg thrust pulse-jet

Hi, I'm building a 5kg thrust pulse-jet, here's the design obtained by eric's calculator (I believe there's drawing attached in the program, but I can't see it, so I made an assumption as below) : Thrust = 5 Kg Exhaust Pipe Diameter B = 4.75cm Tailpipe Length C = 68.10cm Combustion Chamber Length D ...
by skyfrog
Sat Jul 24, 2004 2:19 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

Re: big boost

I am also looking into the possibility of making my own valveless pulsejet website. Does anyone have a good suggestion for a free website-building program, something like 'Site Building for Idiots" ? Take a look at XOOPS , it provides news/forum/web link/downloads/voting/photo album/chat room etc. ...
by skyfrog
Sat Jul 24, 2004 12:43 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

Hi Hank,

Thanks for your info and the compliment regarding my broken English :)

I will stick to the reed valve design, because my instinct told me that it will be easier to obtain my first self-sustained pulse jet engine.

Horace
by skyfrog
Sat Jul 24, 2004 12:37 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

big boost

Hi Bruno, Thanks again. I'm happy because my question has got a perfect answer, and thus I can start my project from this moment. That's a big boost to my project ! I've read your great article regarding the valveless pulse-jet, what can be better learn so much about pusle-jet in such short period o...
by skyfrog
Fri Jul 23, 2004 5:43 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

Thanks steve.

In fact, I'm looking for a 5kg thrust jet engine to power a scale model plane, I have lots of work to do because the status of the project is still on phase zero : setting goal. I hope I can see my plane flying soon.

Regards,

Horace
by skyfrog
Fri Jul 23, 2004 5:33 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

Ooops

Hi Bruno, Thanks for your attention. One thing I have worried after posted this message, I wondered if I could get myself understood in English. Obviously I have to apologize for my bad English. What I really meant was, how did the valve plate (not the petal) get assembled to the front end of open c...
by skyfrog
Fri Jul 23, 2004 12:12 pm
Forum: Valved pulsejet forum
Topic: How to mount the Inlet Reed Valve
Replies: 12
Views: 8131

How to mount the Inlet Reed Valve

Hi, One question please, how does the reed valve get installed onto the front end of combustion chamber ? I see no screws or bolts in many working design. And it's hard to convince me that they got assembled by welding. As you can see I'm quite new to pusle-jet technology, hoping my question won't l...