Main Question or Discussion Point
I see a lot of references to the 'efficiency' of the Tesla turbine, however, I can't find any actual data. Does anyone have a handle on actual achievable efficiencies of the tesla turbine?
I've read everything from 25 to 95% but have found 40-60% to be believeable, based on videos. I scavenged our engineering library on the subject but didn't find anything more than a paragraph related to the subject. Apparently, the efficiency goes down as the rotor spins faster which I imagine is due to the centrifugal force counteracting the corkscrew effect. While researching, keep in mind that these are also referred to as boundary layer turbines and fixed disc turbines. The best resource I have found so far is:http://www.teslaengine.org/I see a lot of references to the 'efficiency' of the Tesla turbine, however, I can't find any actual data. Does anyone have a handle on actual achievable efficiencies of the tesla turbine?
Exactly. The centrifugal force disrupts the corkscrew and creates a back pressure to the incoming fluid. I believe they call this "gating". There is literature on this avaiable on the web. I feel you and I approaching the same reasoning from opposite sides.I'm thinking that, as the speed of the turbine approaches the speed of the stream of working fluid, the boundary layer effect becomes less and less...
I think you are on spot with the vortex and turbine working together.I definitely think we're on the same page, and think you might be right; we're talking about the same thing... But there is a lot of imprecision out there when it comes to explaining the mechanism of agreed-upon phenomena, so I always find it interesting to try to come to understanding of the actual effect at work. I will definitely have to learn more about the centrifugal force in this situation; thanks for the steer on the word "gating". But leaving that aside for a moment (let's say we come up with a method that will negate that effect entirely), wouldn't you think there will still be an efficiency drop as the linear speed of the turbine approaches the speed of the stream driving it? So, assume there is no disruption of the corkscrew at all--- won't we still have efficiency drop as an expected result of the speed differential approaching zero?
I actually found out about Tesla turbines because of work I've been doing on vortex phenomena of all types; it seems like vorticies are one of those (I think of them as 'magic') areas of science where you get a synergistic payoff from what goes in... Of course, there's no such thing as a free lunch, but some things (like latent heat, for example) really seem to have potential benefits that in some way 'go beyond' what you might expect.
I wouldn't be suprised if the 'corkscrew' or vortex effect in the Tesla turbine is an important (if not indeed critical) component of how it functions in the first place.
In my mind an area of focus that most researchers miss, is how little can they get by with. The general approach is to build for high pressures, and output from the least size, which equates to higher cost in almost all respects.Hehehe... I like that.
I really wonder about the thermodynamic component myself... I'd really love to see tests done (or do them myself) to establish some of these things we're wondering about.
Hi Argentina, and IsarmannI think that the end of this discussion is to build a series of different sizes of turbines and variables. Compress air and get how much energy it takes to do it, then expand it on the different turbines, at different pressures and speed to see how much energy you recover. If nobody wants to modeling the system by computer to get the best values of the turbine, disc, gap dimensions and speed of the fluid in motion. The practice will be the only way out. I'm trying to find someone who do the modeling because i have to make a thesis to end my career of mechanical engineering.
Thanks NateD,The test engine I designed and am now building has more then enough variables for a proper parametric study. I can vary direction, disc diameter, disc spacing, and fluid entrance parameters. As I said it'll be enough data to keep me busy for at least 6 months.
Nate, I do not have a degree, what little I do know comes from association of power tools, and equipment that has been used in work and home applications, I depend on the spec plate numbers (on quality equipment) for power ratings for most things.When I started looking at the Tesla Turbine I too looked at varying the disc spacings. I have concluded since that there are better ways to control the throttle. What I have done is designed the engine around max operating power. Varying the spacing of the discs sets up many problems that there are better solutions to dealing with in my opinion. One big issue I've thought about with a variable geometry version is sealing the case properly so there aren't big leaks.
Additionally varying rotor spacing makes things unnecessarily complicated. As an engineer I stick to the KISS methodology.
As to the motor idea... its worth looking into, though I think there is a big difference in the way the air moves when forced into the engine vs when the engine is being used as a pump.
Though I suppose if one could characterize the engine operation as a pump one could superimpose the results onto a forced fluid version. And therefore get a hybrid math model. I'm still not sold on the idea.
The very same data should jump out once my tests are done. The hardest parameter to measure of course is pressure distribution across the discs. But really the most important is to fully characterize the parameters that change as operating and engine parameters change.
What backgrounds do the people on this forum have?
I have a BS in Aerospace Engineering with a specialty in propulsion systems.