The Steamboating Forum

By definition, choked flow is Mach 1.0 The flow will never exceed Mach 1.0 without a streamlined converging/diverging nozzle, plus additional constraints with regard to steam flow. With small steam passages (on the order of 1/8 inch diameter and smaller), even with the best designs of converging/diverging nozzles in attempts to get supersonic flow velocities, success has eluded steam turbine designers for well over a century.

Textbook theory has some practical limits, I have found this to often be the case when trying to build actual steam machinery. The theory developed in undergraduate courses is fairly complex, yet there are many instances where relevant boundary conditions and constraints come into play, and are not addressed at all in the textbooks.

To really get fairly reliable results in high speed compressible gas flow, you need a senior "Rocket Scientist". None the less, stack blowers can, and do, work well.

fredrosse wrote:Textbook theory has some practical limits, I have found this to often be the case when trying to build actual steam machinery. The theory developed in undergraduate courses is fairly complex, yet there are many instances where relevant boundary conditions and constraints come into play, and are not addressed at all in the textbooks..

Well you need to write that better textbook or write that better simulator.

You are basically just saying that the simulation is wrong/that it's too complicated to model. You can see the results in the video, which are impressive and more then adequate for the job and used less steam at the same time then the previous blower. The nozzel was made with some experimentation in the sim, and picked by something that had desirable results in sim. In the end I just asked my friend to make the nozzel but asked him to take a stab at characterizing it and that's what he gave me. I'm pleased with the whole process.

-CB