Welcome! Log In Create A New Profile Recent Messages


Stanley and White Burner Howl

Posted by Caleb Ramsby 
Stanley and White Burner Howl
March 30, 2011 01:29AM
Hello Everyone,

The recent discussion of pulse burners has brought to mind the burner howl issues of vaporizing automotive burners.

Looking back at the various discussions, such as this one ( [stanleysteamers.com] ) it seems that the mixture of the fuel and air is a critical factor. Rich mixtures, either from pushed burners or incompletely vaporized fuel, seems to be the biggest culprit of howling.

Richer mixtures allow a higher flame front speed. So one of my theories is that the howling is actually the individual jets, either in the slots of the drilled holes, trying to burn back through the grate. I believe that the flames trying to wedge into the grates holes produces a greater velocity of the gases going through them, seeing as the fire would now be partially through the grate, so then the flames would leap up out of the grate and back and forth. Thusly causing a modulation of the air and fuel mixture inside the grate. This would then make the burners volume, both the mixing tubes and the distribution chamber a helmholtz resonator and the frequency would be dependent on the total volume of said chamber or maybe just only the distribution chamber.

The people who have stoped burner howl by inducing a draft on the flue of the boiler would have produced a much leaner mixture which would have reduced the flame front speed.

Nergarrd's experiments with his burner also point to the grate. He drilled out the holes in his rusted up burner a bit larger then stock and it howled like crazy. This would indicate that the lessened velocity of the gas mixture through the grate would be the issue. Since he later stopped up some of the holes to get the total grate passage area back to stock, then it ran as it should have and howled at the fuel pressures that it should have.

Kerosine produces a richer mixture becuase of the higher btu gas it produces and has a faster flame front and kerosine burners are known for howling like crazy.

This theory would also fit with the slotted burners being more likely to howl then the drilled ones. The coefficient of discharge is better through a slot then a drilled hole so for a given gas velocity through the grate it would howl at lower velocities because there is less resistance to the flame going back through the grate and the velocity of the gas through the grate would be lower for the same passage area. Since the coefficient of discharge factor basically makes a slotted burner of the same passage area of the effectivally larger then the drilled burner.

The White ran on lower fuel pressures and uses a slotted burner and Jim says it screams at a high pitch, while Stanleys howl at a lower pitch.

Now from what I can tell the White has a much more shallow mixing pan then the Stanley so this would jive with my theory that the mixing pan is working as a helmholtz resonator. Its mixing tube is of rather large diameter and if it were only the mixing tube that was resonating then I would believe that the Stanley would be of a much higher pitch then the White.

Now for the big question, has anyone who has owned a White ever gotten rid of its howl by adjusting the shutter for a more lean mixture?

Whistling Billy had later in its life a burner which reportedly used five jet nozzles going into one really big mixing tube and "whistled". Was the whistling a really high pitched "howl"?

Does anyone know if Stanley's rocket howled? It had, what four or five nozzles and mixing tubes, pushed pretty hard I am sure.

Of interest to this conversation is an aparatus that I came accross in an old dictionary. I can't remember names very well(pyroscope? ) but I sure can remember how things work, so here is how it worked. It was a single flame gas burner with a rotating steel tire with slots in it which hid and revealed the fire as it spun at high speed. Much like the mechanical "moving pictures" of days gone by.

The gas fuel's delivery tube delivered its gas into one side of a diaphram and then onto the burner. The other side of the diaphram was connected to a funnel which collected sound and transfered it to the diaphram, which in turn directed the vibrations to the gas stream, which in turn made the flame jump up and down in frequency with the sound waves. The rotating slotted "tire" gave a stop motion viewing of the flame which allowed one to see it moving.

It would be a curious experiment to make a Stanley like scale burner with the above aparatus engaged to see if the flames are moving or not.

I would love to hear anyone elses experiences with howling burners, how they made them howl or stoped them from howling or any other theories on what the howl actually is.

Caleb Ramsby
Re: Stanley and White Burner Howl
March 30, 2011 05:45AM
Hi Caleb,

My personal current plan is to build burner and test various mixtube/jet size combos to see what -- if anything -- gives a quiet burner. To this end, I have designed a somewhat "David-Warriner-like" burner, with White-like "below thin burner pan" mixing tubes. This allows easy changes to larger or smaller mixing tubes and jets, as needed.

I also plan to use adjustable air-inlet shutters, as did White, but with a somewhat different design from the White air shutters. One thing which I have noticed is that commercially-successful workhorse "Bunsen principle" gas burners, including most household water heaters, space heaters, and gas-stove burners, have an adjustable air shutter at the air inlet. White steam cars used this feature too.

At present, I personally tend toward the theory that "marginally-lean/rich fuel/air mix causes burner howling under some conditions".

Worst-case scenario, to me, currently looks like an automatically-varied air-shutter opening. However, with good design, a fixed-adjustment air shutter may do the job. It certainly works well with various well-designed household appliances, under conditions which vary little more than those experienced on the road with automobiles. One way or another, I believe that a high-output premix-vaporizing gasoline burner can be designed/tuned to give clean and silent firing under all conditions.

Thank you for linking to that very interesting long-ago Stanleysteamers.com thread.


Edited 2 time(s). Last edit at 03/30/2011 10:52PM by Peter Brow.
Re: Stanley and White Burner Howl
March 30, 2011 09:28AM
Hi,,The 1906-07 Stanley racer had 4 tubes,,Does anyone know the dia,,The beach pics show the boiler but the burner is hidden
It is alledged the burner had no pilot,,This MAY be fact or fiction,,,Knowing Freds humor ,,he may just have thrown a handfull of matches in a flooded burner to get the onlookers out of his way,,neat trick,,and this got converted to NO pilot,,,A lot of these things have got twisted in 100 years,,,
There is ""great difference"" in the pan below the cast grate on the Stanley,,and the Amsley burner now called Baker burner,,
The burner in the racer hardley ever howls,,BUT if I shut the valve to the bottles,,I can pump straight through to the nozzles!!! Great control,,,then it will howl and shoot black smoke,When I guess the pressure is perhaps 2-300#,ALONG with howl all the way to scrrreeech,,,not sure if its rich or soot being scoured off the tubes by sonic blast,,!!! Richard will not forgive me for the black soot on his trailer roof,,
The regulation of this burner is very good and satisfactory,even when the burner is down to a wee trickle,,,its a most dosile beast,,couldn't ask for improvement,,,Its a slotted burner,,
Does anyone have info on the 06-07 racer burner,,,Three cheers,,Ben
Re: Stanley and White Burner Howl
March 30, 2011 09:28AM
Burner howl volume can be increased by: Higher main fuel pressure, larger main fuel jets, colder outside air, and a cold burner/boiler. To reduce the burner howl volume, reverse any of the foregoing. It is notable that the the larger the diameter of the burner/boiler, the lower the that the note of howel will be produced. Conversely, a 10 HP Stanley gives a higher pitched howl than say a 20 hp Stanley would give. A little Locomobile steamer can give an ear piercing high pitched howl.
Re: Stanley and White Burner Howl
March 30, 2011 09:53AM
My 10 HP EX burner howl’s when startup from cold. You can really make it scream if you open up the fuel to mush, but once hot it’s just enough noise to know when it comes on and off when driving the car. Hardly noticeable to others.

Re: Stanley and White Burner Howl
March 30, 2011 12:30PM
Re: Stanley and White Burner Howl
March 30, 2011 05:18PM
March 30, 2011 The definitive work on pulse jets is "Pulsating Combustion" The Collected Works of F. H. Reynst edited by M. W. Thring, Pergamon 1961 and it is quite expensive. I found this book in Jim Tangeman's library, speaking of people who know everything and tell little. In Jim's defense I will say that he tells little out of modesty and not because he does not want to share. There is even a short chapter in this book entitled: "Air/Steam Power Plant fired by Pulsating Combustion", so there is nothing new under the sun. Pulse jets are very noisy. I think the book that should be studied while discussing this topic is: "Introduction to Combustion Phenomena" by A. Murty Kanury 1975. It has a lot of mathematical formulas and graphs and tables which is why I just look at the pictures. Tom Kimmel
Re: Stanley and White Burner Howl
March 31, 2011 04:45AM
Hi all

I have a book on combustion. It is more targeted at processing plants. But none the less it hase a very large section on "Pulsating Combustion". Pulsating Combustion is not a Palse Jet. It's a type of forced air combuster. It works more like fule injection where the duty cycle through the fuel valve controles the fuel mix. The valve is part of the fuel nozel.

Re: Stanley and White Burner Howl
March 31, 2011 05:37PM
If the flame front propagates faster or slower than the combustible gasses the flame will pulse and noise is likely. The noise frequency is a result of the flame pulse frequency.

Each jet or orifice may actually extinguish and relight with each pulse as the flame front travels from the orifice to the tip of the gasses and back, hence the volume of noise in some burners.

Peter Heid
Re: Stanley and White Burner Howl
March 31, 2011 10:29PM
tkimmel@locallink.net Wrote:
> March 30, 2011 The definitive work on pulse jets
> is "Pulsating Combustion" The Collected Works of
> F. H. Reynst edited by M. W. Thring, Pergamon 1961
> and it is quite expensive. I found this book in
> Jim Tangeman's library, speaking of people who
> know everything and tell little. In Jim's defense
> I will say that he tells little out of modesty and
> not because he does not want to share. There is
> even a short chapter in this book entitled:
> "Air/Steam Power Plant fired by Pulsating
> Combustion", so there is nothing new under the
> sun. Tom Kimmel


I hate to throw cold water here, but............................

Reynst was a visionary and actually built an interesting version of a pulsating combustor. However, a lot of his writing in this book could be defined as "wishful thinking". He certainly recognized the potential of pulsating combustion but his one claim to success was actually accidental! He decided to extend the stack on his low-level combustor--and luckily for him he stumbled upon a resonant multiple of the primary and experienced a quantum increase in combustion intensity.

There are modern developments that provide far more information than Reynst ever could in his generalizations and inaccurate attempts to quantify pulsating combustion.

I will stand by my statement that pulsejets are far more complex than one can imagine, until attempting the art/science.

Re: Stanley and White Burner Howl
March 31, 2011 10:46PM

Sounds like your burner will have a lot of potential for modifying in case it produces some howling! Good luck with it.


I seem to recall that you said that Freds mechanic used to whipe under the smoke hood of his 1912 or 1913 Stanley with a white hankerchiff and it would come out clean.

Did Fred have a mechanic for the 1906 and 1907 races or did he do his own maintance on the car. Either way I don't seem to recall any articles describing the Rockets runs saying that they heard any howling from it.

I believe that it was the 30 mile run that they "forgot" to tell the Stanleys or Fred that they had changed the starting time to earlier, Fred had to get steam up QUICK, wonder if she howled then?

I have never heard of a Stanley where you could bypass the fuel bottels and have the pump shoot it directly into the vaporizer, is this unique to yours?


That indicates to me that it is a combination of the distribution pan under the burner and the mixing tubes that determines the pitch of the howl. If it were only the mixing tubes then I don't think that it would be that significant of a change, just a few inchs. Also the mixing tubes are very short to being with and would have a very high pitch in regards to their natural frequency.

In a discussion on the Brits board there is talk of a three tubed burner with two tubes being the same and one longer, it produces two distinct notes, but it wasn't said if they shared the mixing pan or had seperate ones. . .


Glad to hear that your new burner is behaving.

By warm up do you meen the burner warms up or the whole boiler?


Thaks for all of the additional links!

Tom, Andy and Dr. Jeckel errr. Mr. Heid,

That is some interesting stuff.

I wonder how much of the "roar" of a open flame or one from a hand torch is fluctuations withing the flame itself.

Flames tend to quite down and reduce in size if they strike each other at 90 degrees. I wonder how much of that is due to mixing or disruption of the "pulsations".


A few other questions.

Has anyone ever heard a pilot light howl?

Does anyone know if Lane burners howl? They were all tube with no distribution grate under the burner.

Caleb Ramsby
Re: Stanley and White Burner Howl
April 01, 2011 12:14AM
Stated above: "Flames tend to quite down and reduce in size if they strike each other at 90 degrees. I wonder how much of that is due to mixing or disruption of the "pulsations".

On the old cars with gas headlights, they have what is know as a flame spreader for the light source in the headlight body. Two gas jets at about 90 degrees to each other, collide giving a broad fan like flame at 90 degrees to their intersection. This wide flame front may be interpreted as "the acetylene gas being fanned out and burning on its own?" It is an interesting burn when lit up. Just one more piece of magic displayed by a noncondensing Stanley steam car.
The pilot light on a Stanley sounds like a small Coleman stove when lit. The pilot light sizzle is what we listen for every time we walk by our steam cars that have their pilot lights lit up. I have never heard of a pilot light howling. It may make a note that is above our hearing range.
Re: Stanley and White Burner Howl
April 01, 2011 12:03PM
Hi,,,The fellow w/the white hanky was Geo,Munroe,,1913 10hp,,royal blue,,,Not sure if he was an official "mechanic" but helped Fred at Galen St,,Brent would know more as Geo. was Brent's grandfather,,,
Re 1906-7,,,Fred was the servace manager,,not sure if he brought others,,don't think so,,,
The race time changed late evening,,,on purpose,,haha,,
If FO had started the burner ,,no pilot,,its doubtful he would leave it on the main on small bottles,,so I think he started the pilot and went to get Fred,,and returned to turn on full fire when all was hot,,Are there any good pics of that burner???
All the puzzle pieces don't quite fit I think,,
If you come over you're most welcome to look at the racers plumming,,it works for me,,,Cheers Ben
Re: Stanley and White Burner Howl
April 01, 2011 02:06PM
To add to Peter's remarks I have always "felt" that the howl was due to a rapidly pulsating flame as the burner back pressure became higher at a faster rate then the high speed fuel from the jets could drag enough air along with the mixture--the velocity head pressure of the fuel air mixture did not increase as fast as the burner/boiler back pressure.
An example would be that I designed a 6" axial exhaust draft blower for Brent Campbell and we tested at the Quecee Gorge Meet all those years ago. We had a U-tube manometer (filled with coffee so we could see it) measuring furnace pressure in inches of water. The 6" axial blower blade was from a junked Wankel skimobile and a long shaft 3600rpm DC motor driving it. The RPM was not high enough to create a large draft but was sufficient so that when traveling along at 50-60mph with full burner on with a great howling going on a flip of the electric switch to turn on the blower assist reduced the howl noticably, possibly by half. We were only drawing about .5-1" of water column but it sort of proved the theory that it was an air starvation/flame modulation problem. The human eye is a very poor instrument for judgement on this as still pictures @ 18 frames per second appear to be moving pictures to our eyes. I wonder if anyone with a frequency meter has ever measured the "howl" frequencies?
Ben, I believe you have the fastest steam car in existence, what an experience that car is.
Best, George
Re: Stanley and White Burner Howl
April 01, 2011 02:50PM
Using a steam jet "stack blower" on a Stanley stops the howl - the extra draught reduces the combustion chamber pressure just like your experimental draft fan. I once put a manometer on the mixing chamber of my Stanley - the pressure was only about 0.5inches of water.

Re: Stanley and White Burner Howl
April 01, 2011 03:20PM
You are so right! The pressure across the grate for a drilled burner may be 1/2-1" water column and Brent was burning about 6GPH with a Baker burner I believe(its a shame to get old and not remember all these things). Then think of a Doble "F" with steam draft booster putting out 18" water column-WOW. It is always quizzical in my mind that big diameter draft tubes/small diamer draft tubes plus lengths all have so many variables. Brents "K" has just two small diameter draft tubes but does it go. The original "K" had supposidly three draft/mixing tubes one manually controlled. My mind searches back so many decades ago when Tom Marshall Sr. cracked his burner grate on his 3 venturi "K" and ordered a new one, believe his answere in an old SACA or Steam Calliope article was with the 2 venturi version "and it never steamed again". Then we get into slotted burners vs. drilled. The flow area is so much greater in the slotted burner but then according to B&W the equivalent diameter of a slot/rectangle is 4 X slot area/perimeter. They knew so much back then when the intuitive fires were burning.
Re: Stanley and White Burner Howl
April 01, 2011 09:47PM
This is a topic that deeply interests me. I am not fortunate enough to own a steam car. Maybe in the next life. I do have some small experience with thermodynamics in the field of deep cryogenics. The burner howl seems like thermo-acoustic oscillation to me. TAO was first documented by medieval glass blowers. They would stick a pipe into a furnace. The pipe was closed on the hot end by a blob of molten glass. The pipe made a moaning sound.

If you Google thermo acoustic oscillation you will find explanations that start out like "The cold gas moves down the pipe to the warm end faster than the gas can exchange heat. The cold gas finds itself in a place where it can exchange heat, warms up and expands back into the cold end." The discussion quickly decays into the kind of language and mathematics that scientists use when they really do not know what they are talking about. This is a difficult subject to understand.

If you dispense liquid nitrogen (-321F) into an open container through a couple of feet of hose or tube, the nitrogen first comes in spurts with a chuff-chuff-chuff sound. When the hose of tube cools down, the flow stabilizes and the sound goes away. This is an inefficient way to dispense liquid nitrogen as the high velocity fluid coming out of the tube tends to blow the liquid out of the open container. The correct method is to use a phase separator which looks like a sintered metal filter on the delivery end of the tube. This allows the gas to get away out the top while the liquid drops out the bottom. The phase separator tends to suppress the oscillation, so people who do this right might not notice the TAO.

The most impressive TAO I ever encountered was on a superfluid helium system. A quarter inch diameter tube was welded into the side of a pipe carrying helium at -458F. The pipe was inside a well insulated cold box. The quarter inch diameter tube penetrated the cold box wall and continued to a pressure transducer on a remote equipment rack. The transducer tube developed an ice ball where it penetrated the wall of the cold box. This is a very serious heat leak in a deep cryogenic system.

I pointed this out to the design engineer. He said "It is thermo acoustic oscillation." "Hogwash!" said I. "This is what you college boys always say when you don't know what is going on. This transducer line has too short a length inside the cold box or the system is poorly insulated or it is inadequately heat stationed." (It should have been thermally connected to a few intermediate temperature structures.)

I then got a hot air gun and played it on the transducer line where it penetrated the cold box wall. By the time I got the transducer line and cold box wall too hot to touch I noticed that an ice ball had formed on the transducer line farther away from the cold box wall and hot air gun. This took some of the smart ass out of me! The heat I was applying to the transducer line moved the ice ball and made it much worse!

I talked to the engineer again. We shut down the system and poked cotton kite string into the transducer line. This damped the oscillation. TAO is often avoided by incorporating a volume tank on the warm end of the line and tuned to suppress the oscillation. It is very much a cut and try thing.

I have experienced TAO on pressure gauge lines severe enough to notice by the swing of the pressure gauge needle. The cycle time may be tens of minutes. Once on a burst disc (pressure relief device) vent I found it to be so fast as to generate a high pitched whistle.

In general, I have noticed that the amplitude of the oscillation is according to the ratio of temperature between the cold end and warm end on an absolute temperature scale. The period of oscillation is generally according to the length of tube between warm and cold.

If rocket scientists can expound on this topic without actually knowing what they are talking about, than so can I! Without ever actually having seen a Stanley or White burner in the metal, it seems to me that there are two possible systems here.

The first system would be the mixing tube between the ambient air and the volume under the burner grate. I wonder what the temperature gradient is across the mixing tube? Do burners with multiple parallel mixing tubes feed a single volume under the grate, or do they each feed separate volumes? Do multiple mixing tube burners howl worse than single mixing tube burners?

Packing the mixing tube with cotton kite string is obviously not going to work, but playing with the volume under the grate might allow one to find a resonance that suppresses the howl. This might require a much larger volume than circumstances allow. The fact that cold burners howl worse than hot burners would lead one to believe that this system is not the culprit. With a cold burner, the temperature gradient across the mixing tube would be smaller.

The second system would be the gas passing through the holes in the grate. The temperature gradient across the grate is much higher, and this would seem to be more likely to oscillate, but the length of the holes in the grate (the distance between hot and cold) is very short. I would think that the oscillation here would be so rapid as to be ultrasonic. Improving the insulation of the volume under the grate would make this area hotter and reduce the temperature gradient across the holes in the grate. Increasing the volume between the grate and the boiler may allow a resonance that suppresses the oscillation, but with the hotter gas, a larger volume would be necessary than in the case of suppressing the hypothetical TAO of the mixing tube.

If the gas is oscillating as it passes through the holes in the grate, a larger number of smaller holes would seem beneficial. Has anyone had experience with the sintered metal or ceramic gas grates? Here you have a vast number of very small passages through the grate. The pressure drop through the sintered metal or ceramic grate may be too much, though.

Again, I do not claim to actually know anything about this. I am sorry to have spent so much of your time with speculation, but as I said, I am deeply interested in this issue.

Re: Stanley and White Burner Howl
April 01, 2011 10:13PM
Hello again:

I believe the most likely reason for burner howl is related to a phenomenon (known broadly as "thermoacoustics"winking smiley that is commonly demonstrated in high school and college physics courses using a device called the "Rijke tube". Here are some links to this interesting device--I believe you will find some similarities to the Rijke tube in your Stanley burners, and a reasonable explanation for the effect:




etc., etc., --just google for "rijke tube" and you'll be overwhelmed with information.

Re: Stanley and White Burner Howl
April 02, 2011 01:04AM
Thank you, Bill. This is interesting stuff. I have skimmed the documents. As I am not as smart as the average bear, the thesis by Konstantin Matvee is going to take some time to digest, but it is the most useful. Of course the Rijke effect is not the only thermo acoustical effect.

The TAO issues that have caused me the most trouble have involved tubes a few millimeters in diameter and several meters long with a few cubic centimeters volume on one or both ends- sometimes a completely closed system except for heat. Convection does not seem to be an issue in many cases. Physical orientation does not seem to matter, but most of these systems have had the cold end down. I was involved in experiments at CERN were we tried to measure heat flow through such systems. We had access to a very good instrumentation including an outstanding Kipitza heat flow meter. The proceedings left me wholly confused!

Mr. Matvee, et al. tell me how to build a thermo acoustic oscillator. I want someone to tell me how to make a thermo acoustic oscillator that I have inadvertently built stop oscillating! The Rijke tube that Mr. Matvee worked with is one meter long. It seems to produce oscillation on the same order of frequency as Stanley owners complain of. What portion of the Stanley burner corresponds to the meter long Rijke tube?

Oscillation occurs when a system has a loop gain of one and a phase shift of 180 degrees. The amplitude increases or decreases until something saturates and gives the required unity loop gain. The period of oscillation shifts until the required 180 degree phase shift is obtained.

To stop the howl of a Stanley burner one could apply acoustic damping to reduce the loop gain- perhaps by acoustic insulation in the resonating structure. One might also try to reduce the temperature gradient which drives the oscillation. One could also attack the problem by modifying the tuning to increase the phase shift at frequencies that are troublesome.

The question is: Where exactly is the oscillation occurring? I have read that Stanley burners howl even when not attached to a boiler, so that leaves us with a mixing tube, a volume below the fire grate and the fire grate itself. How can such a simple system be so confounding?

Re: Stanley and White Burner Howl
April 02, 2011 06:11AM
Hi Kerry,

>To stop the howl of a Stanley burner one could
>apply acoustic damping to reduce the loop gain-
>perhaps by acoustic insulation in the resonating

One hypothesis about my burner design which I am eager to test, is that the 1/2" thick ceramic fiber/fabric insulation in channels atop the grate, may have a damping/muffling effect on any sound pulses occurring above the grate.

The grate structure of this burner may also have a damping effect on pressure pulses above and below the grate. "Modifiable/modular" grate is designed to be built of sheetmetal channels with spacers and flame slots between them; open tops of channels are filled with ceramic fiber insulation strips forming floor of firebox. Well, add some cyclic pressure differentials between top & bottom of grate, and the channels and spacer strips between them should flex ever so slightly. Friction between them may have a damping effect, akin to the damping friction between the layers of a leaf spring -- perhaps just enough to prevent any oscillations from getting started. Whereas typical one-piece burner grates may act as acoustic diaphragms -- often heavy and with inherent oscillation frequencies of their own.

D.A. Warriner built a burner with a "modular" grate built up from corrugated wood fasteners lined up in the tops of fuel/air mix distribution channels, to eliminate slotting and drilling work. It reportedly worked very well. I can not recall whether he reported burner howl or not; does anyone remember?

On top of that, the boiler which my burner is intended for has ceramic fiber walls behind the gap-tubed water wall. And there's more blanket/fabric lining the inside of the exhaust flue. The whole boiler/burner unit may have the acoustic dampening characteristics of a giant "glasspack" muffler.

With gremlins afoot however, all these factors may just "Murphy" together into the loudest howling ever heard from a steam car. smiling smiley

With so many things going on inside this contraption, I won't know more until I build, run, and tune it. Hopefully lighting one of those "intuitive fires" which George refers to.

>One might also try to reduce the temperature
>gradient which drives the oscillation.

Many vaporizing burners quiet down when they warm up.

The steam car literature contains many reports of well-behaved vaporizing burners like Ben's, Rolly's, and others mentioned on this Forum. I have seen reports of burners which were claimed to not howl under any conditions. Light steam power burners tend to undergo many changes during testing/tuning. Perhaps one or more tuning changes in some vaporizing burners eliminated howl without the experimenters/developers understanding why. A nice result from a practical point of view, but also intellectually unsatisfying!

Re: Stanley and White Burner Howl
April 02, 2011 06:54AM
Hi George and Mike,

Thanks for your reports on experiments with forced-air and exhaust draft. These, and many other observations and experiments, do seem to support the "air starvation" theory of howling. For the same fire without howling, fit bigger mixing tubes? Of course that is not an option when modifying original or reproduction Stanley burners -- bigger tubes won't fit in the pan. Also the grate opening area and gas flowpath through tube stack have to be considered, maybe increased to match bigger mixing tubes if the desired firing rate is not reached.

Flared mixing tube inlets and some other changes seem to give good "howl control" too. It all seems to point to the fuel/air mix. A rich (or lean? ) mix seems to give unstable and pulsating combustion, which is then "tuned" to frequency by the dimensions/geometry/characteristics of the "resonating chambers". My first efforts will be to avoid unstable combustion, so that resonance and damping never become issues.

Somewhat oversized mixing tubes with adjustable air shutters look promising at this point.

Re: Stanley and White Burner Howl
April 02, 2011 11:48AM
Pulsing of the flame front causes pressure waves that emit sound whose frequency is directly related to the pulsation frequency. The shape and size of the fire box and it's attachments can serve to resonate the sound to disturbing levels. There are 2 general reasons why the flame will pulsate.

Turbulent jets of air / fuel emit a noise whose intensity is relative to the amount of turbulence, and combustion increases the intensity by about 20 to 40 dB. If the initial fuel air mix has spatial and temporal inhomogeneities in the combustion zone, they cause fluctuations in the rate of combustion. These fluctuations are often in the 1 to 2 pulses per second, but it has been shown that hydrogen rich fuels can increase the frequency. If the fuel is not premixed with the combustion air, you will always get a flame that pulses at least slightly. With premixing you avoid lean and rich pockets in the combustion zone and this type of pulsing is eliminated.

The second type of pulsation is when the flame front travels at a different speed than the fuel air mixture coming from the orifice. If the flame travels faster than the mixture exiting the orifice, the flame will travel down the jet of mixture to the orifice and may briefly extinguish as the fuel supply is momentarily depleted. This process causes a pulsation as the process continues over and over.

As you can see the introduction of extra combustion air may greatly effect the post mix burner but will have little effect on a premix burner. Premix burners are common in kitchen ranges, propane grills, and gas fired central heating furnaces, not usually steam cars.

The work of Sage and Schroeder on pressure jet burners showed that dampening of the acoustic system was very effective. They surrounded the fire with a shield that had 1/2 inch holes drilled in it which served as a muffler by allowing normal pressures to easily escape, but pulses are moderated. They found it easy to muffle the sound with less than 1% loss in efficiency.

Peter Heid
Re: Stanley and White Burner Howl
April 02, 2011 04:15PM
Do atmospheric burners, like the Lane, suffer from this same howl?
Re: Stanley and White Burner Howl
April 02, 2011 04:47PM
Yes the whole thing is rather complex and the diameter and volume of the mixing tubes, the volume below and above the grate and the very small back pressure in laminar longflow thru the stanley boiler is like tying and understand a very complex loudspeaker design such as was proposed in the 1980's by an english engineer. he found that the simple single tube bass reflex tube design with its tumed boominess could be smoothed out by dividing the acoustical box into two boxes, each with a tuning port plus a tuning port between the boxes. It allowed a small speaker to create low crisp clean non'boomy frequencies and very high acoutic efficiencies above 90+ %, the throbbing but utter cleanliness of a ripping tuba solo is unbelievable!! So the whole mess of things about a Stanley system is about such acoustical things. I had designed, from the inventors theorys, a small two box three tuning port system and took it to "Tweeters" that had advertisized "bring in your speaker and compare it to the new Boston Acoustics models" and my little homemade speaker system blew its doors off, not that i understood the physics behind the invention but simply used the equations. So it is difficult to design a vaporizing system considering the resonate frequencies and velocities of the mixing tubes, the under grate area, the resistance of the grate, the volume above the grate to establish a quite system over the range of firing conditions. I mentioned that Brents "K" had very small diameter mixing tubes but that resulted in higher air-mixture velocities , velocity squared.2G/800 X12 is the inches of water pressure it developes to get it thru the grate. We need a REALLY GOOD PHYSICIST to analyze this stuff for making burners quite. In my old dys t MIT asked two PHD's in heat transfer degrees to analyize the Tesla turbine and they both said they didn't have the expertise in that kind of laminar flow field, just think 100+ years ago a simple Tesly turbine by using shear forces could equal the steam rate of then popular bladed turbines in the range of 30#steam per hour with 100psi sauurated steam. The question of howling is a very complex acoustical problem wth a bunch of in line series systems tied to each other.
Peter H. if you can find me a modern copy of CE please do it and I will pay your expenses.
Re: Stanley and White Burner Howl
April 02, 2011 05:09PM
Lanes probably will howl as they still have a venturi and jet system. I have an industrial gas heater in my shed which has a jet and venturi just like a Stanley, feeding into a grid of tubes with burner holes on the top. It has a secondary air supply because the bottom of the casing, like a Lane but unlike the Stanley, is open to the air. It howls really loudly for a few minutes when first turned on. We also have a wood burning stove which when first lit and given maximum draught by having the air intakes fully open, burns with a massive low frequency pulsation which is strong enough to send flames out of the air vents in the door and rattle the doors and windows of the house! Same process as howling.

Be careful Peter with the size of your venturi - big ones have been tried and give a lesser induced air flow - there is an optimum. Interestingly I once fitted a small wind deflector and few inches in front of the venturis to discourage "flame outs" at high speed. I soon took it off as the burner howled all the time either because it restricted the air flow ( the converse of using stack blower) or possibly, but less likely, interfered with the accoustic propeties of the venturi.

Re: Stanley and White Burner Howl
April 02, 2011 05:50PM
Mike,,can you describe the burner,,or pics,,,,you may have a very early Stanley burner,,,they were different,,,Ben
Re: Stanley and White Burner Howl
April 02, 2011 07:37PM
Hi George,

I agree, it would be great to see a really good physicist figure out all this stuff. The burner design which I plan to build and test is based closely enough on the Ottaway parameters that I think it will work well. The downside is that Ottaways are noted for "howling", at least at higher firing rates. So my burner project is more of a "tuning/modifying" project than a "clean-sheet design". One thing which might help is that I am not pushing my firing rate to the maximum achievable with the Ottaway parameters. It should behave more like an Ottaway behaves at lower firing rates.

One interesting bit is that Bunsen-principle natural gas burners, as used in stoves, water heaters, some space heaters, etc., have a slight taper in their mixing tubes -- tubes expanding gradually in diameter as they approach the flameholder. All the examples which I have operated burn nearly silently, certainly no howl, including stove burners with a very wide range of outputs, from the slightest "simmer" to big sheets of flame. Is the mixing tube taper part of the reason for their quiet running? Steam car vaporizing burners, at least the ones whose details I am acquainted with, don't have that taper. Just straight pipes. For natural gas burners, it is a standard taper, btw; 1 in 12 if I recall correctly.

Hi Peter H.,

I think that the operating principles of bunsen-principle natural gas burners and typical steam car vaporizing burners (Stanley, White, etc) are the same. The only difference is that the car [and Coleman etc] burners vaporize liquid fuel into gas first. If natural gas burners run quietly, even over a wide range of firing rates, then it should be possible to make a quiet vaporizing burner.

Quiet steam car vaporizing burners have been reported. Fortunately it is not the case that all such burners howl, or that a quiet example has to be developed from basic principles.

Spatial and temporal variations in fuel/air mix ratio might be going on, but that would need measurements to verify. Seems like fuel vapor (gas) should mix very rapidly and completely with combustion air, considering the distance between jets and flame slots in a car burner. If there are variations, they must be extremely slight and brief, as these burners tend to produce uniform and steady masses of blue flame -- at least to the naked eye.

There are other factors which don't seem to square with some of the howling theories. For example, in the thread which Caleb ran a link to above, I referenced a Stanley Dealer Bulletin which reported burner howling caused by weak-burning pilot lights and main jets not properly centered/aligned in their mixing tube ends. The Bulletin said that tuning these things eliminated the howl.

Hi Mike,

Thanks for the tip on venturi/mixing tube sizes. I plan to start with essentially the same parameters as used in the successful Ottaway burners (I based my design on the Ottaway blueprints), and make slight modifications, in steps, from there. So at least I should be starting with something that works -- gremlins permitting of course. Then see which changes, if any, quiet it down. The burner is designed for rapid and relatively easy modification -- many different things can be built and tested in a relatively short period of time. Jets and mixing tubes have to be sized to work together.

Re: Stanley and White Burner Howl
April 03, 2011 06:00AM
Thinking a bit more about it, the Ottaway-based vaporizers and jets should deliver the amount of fuel needed at the desired temperature and pressure. So the experimenting should focus on the mixing tubes and grate, to get the best results with the "given" vaporizers and jets.

Making and swapping the mixtubes is fast and easy enough that I might start with tapered tubes which run the full width of the burner, instead of only to the middle of the pan as in White, Ottaway, and some other burners. Longer mixing tubes have been associated with quieter burners -- better mixing? Or perhaps this changes the acoustics of the system in the "quiet" direction? This could be combined with an inner baffle extending about halfway across the pan, beneath the grate, as in Stanley and Baker burners, to direct fuel/air mix entering the pan back toward the pilot end of burner.

The tapered tubes would be in accord with modern Bunsen-principle gas burners, and the "full length" mixing tubes and "halfway baffle" would be in accord with Stanley practice.

Per Peter H.'s mention of Sage and Schroeder's perforated dampers, if howling occurs, perhaps a second, perforated, baffle could be added inside the pan, between the grate and distributing baffle, to break up any resonance inside the burner pan.

Once mixing tubes are sized/tuned for good blue flames, if howling occurs the grate opening area can be changed in small steps until (hopefully) the howling is eliminated. If needed, a secondary baffle and/or other damping means could be tried during this stage.

Re: Stanley and White Burner Howl
April 03, 2011 08:49AM
Peter B

Given what Peter H tells us (seven posts back) about the second form of flame pulsation:

"If the flame travels faster than the mixture exiting the orifice, the flame will travel down the jet of mixture to the orifice and may briefly extinguish as the fuel supply is momentarily depleted. This process causes a pulsation as the process continues over and over."

The way to increase the velocity of the mixture is to use smaller holes and more of them. I have read several accounts of burner howling getting worse after drilling out burner holes.

Doubling the diameter of the hole should decrease the velocity of the mixture by a factor of four, ignoring edge effects. Given that thousands of holes may be involved in the average burner, drilling a substantially larger number of smaller holes does not seem to be an appealing task.
Re: Stanley and White Burner Howl
April 03, 2011 11:20AM

Sorry but I ran out of time on my other post. I should have mentioned that it works both ways. If the fuel vapors exit at a speed that is too much above the flame propogation speed, the flame can be pushed to the very tip of the vapor cone and be blown out, only to reignite near the orifice and start the process over again. You are best to have a vapor velocity above the flame velocity to prevent burning right at the orifice so carbon has less chance to develop around it and possibly obstruct the flow. I have not found any information as to the range of acceptable fuel speeds, but too fast or too slow can cause pulsing.


If I am not mistaken, a bunsen type of burner mixes air with the fuel before it exits the orifice into the combustion chamber, and most vaporizing burners like the Stanley, only fuel exits the orifice. Most large power plants mix air in 3 stages, primary, secondary and that 3rd one I can't spell right now. Imagine the noise of a 20 mbtu/hour burner if the flame were allowed to pulse, then put 4 in a combustion chamber. It has been shown that only about millionth of the energy in the fuel is turned into acustic energy, but even in a small burner it is enough to shake things apart.

Spatial and temporal variations in fuel/air mix ratio are going on, and a fast camera is all you need to see it. One of my text books has great time lapse photos of how this happens. Usually something like 20 frames per second is all you need, but infared imaging is better. If the vapors are exiting the orifice at 20 feet per second and the flame is only 1/8 inch away from the orifice, leaving only about 0.0005 (1/2000) seconds for complete fuel mixing and combustion. It will not happen !

George N,

I will look for a copy for you. These noise issues are comon to most forms of combustion, even burning coal, I am thinking of our wood stove that you can make pulse so well that it looks like someone is sending smoke signals from the stove pipe. You can get to pulse enough that it can be felt any where in the building. A lot of work was done on early home oil burners to reduce flame noise also.


I believe the Stanley buletin was concerned with the fuel not vaporizing fully. The finer the particles, the faster they will mix with combustion air and a more homogenous charge has less chance to pulse. Unless you know exactly what you are doing, never try to convert a post mix burner into a premix burner. If done wrong the flames can enter the orifice and ignite the premixed fuel inside the burner and an exposion is likely.

Peter Heid
Sorry, only registered users may post in this forum.

Click here to login

All files from this thread

File Name File Size   Posted by Date  
Cracked casting.JPG 192.5 KB open | download Rolly 04/04/2011 Read message
Old Venturi tube.JPG 150.9 KB open | download Rolly 04/04/2011 Read message
Drill Pattern.jpg 32.8 KB open | download Rolly 04/04/2011 Read message
Burner & Pan.JPG 152.3 KB open | download Rolly 04/04/2011 Read message
Cracked casting-2JPG.JPG 165.7 KB open | download Rolly 04/10/2011 Read message
new castings.JPG 152.7 KB open | download Rolly 04/10/2011 Read message
Drilling.JPG 213.3 KB open | download Rolly 04/10/2011 Read message
Drill jig.JPG 177 KB open | download Rolly 04/10/2011 Read message
Drill pattern (2).JPG 77.9 KB open | download Rolly 04/10/2011 Read message
three gang drilling head.JPG 861.6 KB open | download Rolly 04/11/2011 Read message
White burner.JPG 152.2 KB open | download Rolly 04/11/2011 Read message
P4110053.JPG 124.9 KB open | download Rolly 04/11/2011 Read message
SAM_3002.JPG 3.12 MB open | download frustrated 04/13/2011 Read message
SAM_3003.JPG 3.17 MB open | download frustrated 04/13/2011 Read message
SAM_3004.JPG 3.12 MB open | download frustrated 04/13/2011 Read message
SAM_3005.JPG 3 MB open | download frustrated 04/13/2011 Read message
SAM_3008.JPG 3.15 MB open | download frustrated 04/13/2011 Read message
SAM_3006.JPG 3.14 MB open | download frustrated 04/13/2011 Read message
SAM_3009.JPG 2.95 MB open | download frustrated 04/13/2011 Read message
100_1680.JPG 1.11 MB open | download Peter Brow 04/14/2011 Read message
corrugate.jpg 58.6 KB open | download frustrated 04/15/2011 Read message
037-7.jpg 38.3 KB open | download kdc2 04/15/2011 Read message
042-3.jpg 48.8 KB open | download kdc2 04/15/2011 Read message
CCF18062008_00001.jpg 792.6 KB open | download chris Wedgwood 04/18/2011 Read message
New gauges.JPG 86.7 KB open | download Rolly 04/29/2011 Read message