Speed of the flames enering the heat riser from the burn tunnel.

Pondering how fast the river of flames travel on my batch fed rocket mass heater.Observed a lot of speed at times ,but can not figure how to measure it's speed.Any ideas? Thanks .Mr. Curious.Tony

This is a standard chemical engineering rate of reaction problem. If you know the volume of air that it is sucking in, then you know the rate of consumption of one reactant. Then model it as the combustion of a standard carbohydrate (CnH2nOn) and you can figure out how much additional exhaust gas is being created. The addition of the input air volume plus the volume of the gases generated will then allow you to calculate the speed of the exhaust gases.

That is a lot of info that I am unable to process.Thanks for the try but I can not figure in those terms.Tony

Tony, we've spoken about that on Donkey's forum.

My take, is to get a computer fan, put it in a tube, with the gaps around sealed. Put an inline anemometer in the tube and feed it with a hair dryer for example. see what voltage you get at the two or three speeds. That could give you a scale, and fitting this fan to an airtight door, with a piece of tube, to keep away the fan from the fire. Or you could use teh anemometer straight away, if you're sure you won't burn it.

Thanks all.At least there is a possibility to measure the velocity.HAve a good day.Tony

tony Irving wrote:Thanks all.At least there is a possibility to measure the velocity.HAve a good day.Tony

If you can rig up some sort of anemometer and figure out the airflow into it, just let us know (and the dimensions of the inlet and the burn tunnel) and I will be glad to run the calculations for you.

Tony, by the sparkles exiting my heat riser, i'd say between 5 and 10m/s (i'm used to those measurements, because i work on chairlifts, and over here, speed of the cable, and wind speed are calculated in m/s. In the wind, snow flakes make a very good visual indicator. )

Satamax Antone wrote: i'd say between 5 and 10m/s

5 m/sec is 11 mph in American units, sounds like a reasonable value.

11 miles per hour sounds close to the speeds I have observed during a full burn.I will be satisfied with that.We shall call it good.Thanks to all who replied!