The Siren Board

ENec wrote:I wonder what would happen if someone put a single phase motor on a 3 phase series A1 blower.

it would run.

the blower doesn't care what kind of motor is driving it so long as the motor has enough horsepower.

I wonder how much better it'd roar with the Hurricane's monster 30-hp blower, with all relief devices disabled.

Thank you guys. Bobcat418 I was a little curious about the same thing... I don't know what would happen if you somehow put too much air in it... I guess no one has done it before (thankfully) and I am glad to know i won't be the first to do that. Alright now on to saving up for this dang thing...

At some point an excessive amount of air to the chopper would overload the chopper motor. The increased out rushing air would at some point be too much for the motor to overcome and cause a motor stall. Now if you increased the horsepower of the chopper motor to accommodate the increased air load would that significantly increase the sound output? Hmm?

But you would approach the point of diminishing returns. All that air has to get forced out a hole the size of a piano key. Too much backpressure and all you would do is increase the blower discharge temperature and sound output would level off. I think the 5M thunderbolt was pretty much the max of what the siren could do.

It's sort of like boost in a forced induction engine. You get to the point where you have too much and the horsepower drops off sharply, right before you blow the head gasket or hole a piston.

holler wrote:But you would approach the point of diminishing returns. All that air has to get forced out a hole the size of a piano key. Too much backpressure and all you would do is increase the blower discharge temperature and sound output would level off. I think the 5M thunderbolt was pretty much the max of what the siren could do.

It's sort of like boost in a forced induction engine. You get to the point where you have too much and the horsepower drops off sharply, right before you blow the head gasket or hole a piston.

Wasn't the 5M DB output around 128 to 129 DB @100 feet?

Don't know exactly since Federal rated them the same as the rest of the tbolts. They are noticeably louder in person.

For a while in the 80's the C series 1000 was rated at 130.

Oh yea! Seems the thunderbolt had the same DB range that the 2001 series has. Sounds to me like they have a DB range of 127 @100 to 130 @100. Wouldn't that make the C series thunderbolt the same DB rating as the Hurricane?

I don't think you could overload a Thunderbolt without something like a very large (industrial) screw compressor. The first thing to happen would be acoustically overloading the throat of the horn with air turbulence. As the pressure increases, supposing there is unlimited flow available, eventually the velocity of air in the horn throat will cause the flow to become so turbulent that the system no longer produces additional output corresponding to the additional available pressure. (The answer to this would be to increase the size of the chopper exit ports.) Then the seal where the rotating head interfaces with the stationary standpipe would fail, and you would lose pressure there. If you just couple the air source to the head without this seal, the seal where the chopper cap attaches to the chopper motor housing would fail next. All this would happen before any metal parts would fail.

I think the 'safety valve' in the Thunderbolt's blower enclosure is there to protect the blower, not the siren head. If the blower were dead-headed, the power consumption from the motor would increase substantially, and if the blower motor operated in this condition for too long, then it would overheat and fail from burnt windings. Normally, the blower motor and rotator motor are sized to run continuously without failure, though the chopper motor is not designed to run continuously.

the other thing to consider is that there's only so much air you can pass through a restriction; in this case the stator port. When you push (or pull) a compressible fluid like air through a restriction, its pressure drops while its velocity increases. once its velocity approaches the speed of sound (Mach number reaches 1.0) the flow is choked and it can't go any faster no matter what you do.