Testing the sound output of a Small Pulsejet
Posted: Wed Oct 01, 2014 8:30 pm
I just got this one going, after a 1 year break, Hooked it up to the tank, lit it up with a Lighter, and ran it up to Full Throttle.
Loud little sob. Used my DB Meter to see just how-many Decibels it would put out, My meter is calibrated to a Police DB Meter, so I know it is Accurate.
This PJ is my first I ever built, using PyroJoes formula for Newbees, Built it with his Caliber Method and added a cone of about 20deg. to the CC, on the exhaust side.
Put a bigger intake pipe on it so I could change size and length to fit the power needed, Kind of. As I dont really know what Im doing quite yet with a PJ Motor.
The exhaust is at 39mm, and the rest according to PyroJoes Formula.
I placed a smaller, flared pipe into the Intake, about 8mm smaller, leaving the pipe end flush with the CC end, just as its supposed to be, and the flared end almost flush with the bigger intake pipe.Leaving a small space between the 2 Diameters.
Its hard to explain, but I think it did the trick, as now it starts without any air help, I just open the gas, light it, and off it goes.
Ill make a plan for how I did it later, I used a Flowbench to measure the backflow on the 2 pipes, as I thought I was getting to much blow back through the Intake, not letting it run without starting air. Guess I hit the right nail this time.
Vid of the DB Meter going wild, as it went over 120db, youll see it bouncing around at the end of the meter, LOL, but the sound was still increasing, I think its about 135-150db
(I have to buy a BIGGER DB Meter )
https://www.youtube.com/watch?v=nkhv5v5 ... e=youtu.be
I will be posting in here more often now, as I had troubles last year (Not the Noise Police either) LOL, and will have more time to endeavor into the realms of Pulse jets.
Frank
Loud little sob. Used my DB Meter to see just how-many Decibels it would put out, My meter is calibrated to a Police DB Meter, so I know it is Accurate.
This PJ is my first I ever built, using PyroJoes formula for Newbees, Built it with his Caliber Method and added a cone of about 20deg. to the CC, on the exhaust side.
Put a bigger intake pipe on it so I could change size and length to fit the power needed, Kind of. As I dont really know what Im doing quite yet with a PJ Motor.
The exhaust is at 39mm, and the rest according to PyroJoes Formula.
I placed a smaller, flared pipe into the Intake, about 8mm smaller, leaving the pipe end flush with the CC end, just as its supposed to be, and the flared end almost flush with the bigger intake pipe.Leaving a small space between the 2 Diameters.
Its hard to explain, but I think it did the trick, as now it starts without any air help, I just open the gas, light it, and off it goes.
Ill make a plan for how I did it later, I used a Flowbench to measure the backflow on the 2 pipes, as I thought I was getting to much blow back through the Intake, not letting it run without starting air. Guess I hit the right nail this time.
Vid of the DB Meter going wild, as it went over 120db, youll see it bouncing around at the end of the meter, LOL, but the sound was still increasing, I think its about 135-150db
(I have to buy a BIGGER DB Meter )
https://www.youtube.com/watch?v=nkhv5v5 ... e=youtu.be
I will be posting in here more often now, as I had troubles last year (Not the Noise Police either) LOL, and will have more time to endeavor into the realms of Pulse jets.
Frank