Calculating Hbar Tsr

[vawtman]

Ive always claimed my 8x8 had a tsr of 6 because the driveshaft would spin at 60rpms in a 10mph wind unloaded.What would the formula be for the actual blade speed?Is the actual tsr measured after the gen is installed?Just buggin me.Its finally warming up and planning to hook up a couple conversions on it.Thanks

[rotornuts]

I think your tsr is 1.7 which would make much more sense than 6.

You need to determine how far your blade will travel in feet in one hour then divide that by how many feet are in a mile(5280) and presto you have how fast your blades are going in MPH. Divide by the windspeed to detemine ratio.

Hint: 3.14(Pi)xD = circumference

Mike

[Nando]

The actual formula:

rps = rpm/60 = REVOLUTION PER SEC

D = mill diameter in feet

WIND VEL ft/sec= (MPH * 5280 ft/mile )/ 3600 sec/hour

TSR = (RPS * pi * D) / ( WIND VEL ft/sec)

60 RPM = 1 RPS

Pi*D = 3.14 * 8 feet/mill = 21.133

Wind Vel = (10 mph * 5280)/3600 sec/hour = 14.666

TSR = 21.133 / 14.666 =

FOR TSR = 6 the RPM = (60 * 6(tsr) * 14.666) / 31.133 = 250 RPM

Does it help

Nando

[windstuffnow]

  I find the formula below a bit easier...

Windspeed x 88 / circumference x TSR = rpm

windspeed in mph

circumference in feet

So;  10mph x 88 / 25.13 x 6 = 210 rpm

And yours is running...

60 rpm / ( 10mph x 88 / 25.13 ) = TSR of 1.71

Just like rotornuts said...

Oh, the "88" simply converts mph to feet per minute

.

[Nando]

YES, - but I was showing "reasoning" for future reference to be able to recognize how the basic formula develops.

I prefer the metric system and I could have just given the conversion factors BUT the reader may feel ackward with them.

Nando

[vawtman]

I owe everyone who followed my posts over the last few months an apology for false advertising.I thought that if the shaft was spinning 6 times faster than the wind that was the measurement.Im sorry and shouldve studied more before making that claim.At least I cant say I didnt learn anything today and glad to get that out of the way.Thanks guys.

[Nando]

I think that you learned something VERY useful today:

The need to learn to do calculations to define what you have, and learn the steps TO MINIMIZE EXPENSES and time wasted.

I discovered this fact when I was 14 years old and developing a small hydroelectric turbine to produce 30 + watts.

Nando

[vawtman]

Nando the rotor and blades cost me about 50bucks and I like wasting my time on these things.Im still happy with the machine due to the fact that it can self start in low winds and that was my goal with it.Dont tell me you didnt waste time and money on projects.Its fun

[electrondady1]

 i just like to make sparks, well making lights glow is cool.hydrogen is fun! next comes battery charging. and then the holy grail,toasty baseboard heaters!

[IntegEner]

It is tempting to add 2 cents to this. The TSR can also be defined as the actual blade velocity relative to the wind it sees parallel to its motion divided by the wind it sees at right angles to its motion to make it the same parameter as the TSR for the horizontals turbines. Otherwise it is some different thing that applies only to VAWTs. Of course, such a blade TSR varies up and down throughout its rotation, reaching infinity at the two points where the blade is moving parallel with the wind and the wind crossing it is zero. There is nothing wrong with being precise in these things and that is why so much is said on the IntegEner-W website in the Wind Theory section at www.integener.com .

Anthony C.

www.integener.com

[IntegEner]

In adding a bit to this, the TSR of the horizontals wind generators varies along their blade lengths with the tangential speed of the blade increments selected but remains the same over time with a steady wind. Meanwhile, the TSR (the "true" TSR as defined above) of the verticals H-Rotors is the same all along the blade lengths but varies over time and as the rotors move throughout their circuits of rotation. It typically goes from a minimum value near dead center on the faces of the upwind and downwind sides to infinity at the points at right angles to these, where the wind crossing the blades reduces to zero.

The TSR is important as a determinant of how efficient the blade can be in converting the energy in the wind. This is the "blade" efficiency, different from the "Betz" efficiency, and it can go from nothing to 100%. Graphs of all these concepts are provided for everyone to see in the Wind Theory section of the IntegEner-W website and, again, being precise about all this is important and the way forward in development of these technologies. I hope this doesn't take away from the "fun" of creating projects because sometimes "fun" is assumed to be "making fun" of "high falutin'" and "scientific" thinking. Without this extra precision projects are always at risk of becoming "also rans" and die for reasons that are never understood. (Doesn't that sound familiar!!)

The TSRs of the verticals, being so high as this description of them now makes clear, are typically higher than those of the horizontals, which go to zero at the blade roots and sometimes have difficulty reaching the low values of just one or two up along their blade lengths. This is a benefit and can be said to add to their inherent possibilities (however, realizing they also have their down sides).

Anthony C.

www.integener.com

[finnsawyer]

TSR stands for "Tip Speed Ratio".  As such, it has no meaning for any point along the blade of a horizontal axis wind mill other than at the tip.  It's actually a defined parameter used in the design of the blades, although there obviously exists some ratio at any time the mill is operating.  I would also say it has no meaning whatsoever for a VAHT.  I suggest you come up with another term to define what you are talking about.  All you are doing is sowing confusion.

[IntegEner]

Going even further on this, it is true that the TSR often taken for the horizontals, that is the TSR at the blade tip, or the "tip" TSR, is the maximum TSR for the blades, everything else along their lengths being less.

It is the opposite for the verticals. The TSR often taken is the tangential speed of the H-Rotor blades divided by the wind speed and this only holds at the dead centers of the upwind and downwind faces of the swept area. Everywhere else it is greater and so it is the minimum TSR for the rotor.

The horizontals struggle, in other words, to keep their TSRs high and the verticals have little need once they gain a rotor speed 1.5 or 2 times the wind speed of going any faster than just this set speed. Their TSRs are plenty high already.

The other reason for a fast rotational speed, that is, the need to slice up the wind into thin slices like cheese, is at least partly helped in the verticals by the blades' traversing their swept areas twice each rotor rotation. It is sort of double duty, unlike the horizontals blades. Some recent efforts have been resurrected about the past contra-rotation horizontals in which a second rotor placed just behind the first rotates in the opposite direction. For the verticals, of course, the blades already do this on the back side without the added complexity of such an arrangement.

Contra-rotation, be it known, still has its adherents and even Federal and State governmental energy agencies have demonstrated a soft spot for it. It can be easily understood as just a turbine that combines upwind and downwind rotors on its nacelle, sort of two turbines in one. Trouble is that blades going at TSRs over 1.5 or 2.0 have shown good efficiency and even theory says they can be over 90% efficient in doing so, obviating much of the need for this feature.

The question remains, though, why most all modern turbines, even the best, do not approach the Betz limit any closer than they do and this is forms a puzzle and opportunity for those who can understand these problems and suggest solutions. It certainly can be useful to look at some of these details.

Anthony C.

www.integener.com

[IntegEner]

It might be said as yet another comment on this that the verticals done to this date have been unaware of a way of compacting their sizes and increasing their blade swept area efficiencies. It is becoming manifestly improbable that they will ever expand their rotor diameters beyond a certain point, an important reason being that their rotational speeds tend to be more limited than those of the horizontals. Their strengths have always been in their heights and their ability to reach high up into the sky, given the right design support, to begin with.

What is suggested is to look at them in multiples of, say, three placed adjacent to each other in a triangular configuration on the ground. The wind is accessed by their blades for energy conversion best in their swept area centers upwind of their axes of rotation and the conversion efficiency tapers off towards their outer edges on both the right and left, leaving a lot to be desired, but a lot of energy remaining and available for other rotors just downwind. So no matter from which direction the wind is coming, a "three-per" arrangement, all three rotor upper bearings supported together by the same supports, either the simple guy wires or more substantial outer framework seen on some, would automatically pose high efficiency portions of their rotors across a wider area for the total width of the entire structure.

This may not seem like it is worth the effort until the idea is expanded to encompass an entire square mile of wind farm. To create just one huge rotor of one mile in diameter would be nowhere as efficient as backing up shorter diameter rotors in just such a way due to the lost efficiency over such a large territory otherwise. I think the point is clear. Multiple rotors spaced near each other and connected tend to be more self-supporting as well, allowing for more possibility of gaining that added height. I cringe, though, when I think of what befell some of the Darrieus turbines in earlier years here on the West Coast. The wind can be a hard task master.

So much for these possibilities as random thoughts.

Anthony C.

www.integener.com

[finnsawyer]

Considering that "TSR" has "Tip" as part of it I will stick with it applying only to the ratio at the tip of the blade for an HAWT.  For any other point along the blade it will be "The Speed Ratio at that Radius".

While I have no interest in telling you VAHT people your business, I would like to state that my interpretation of TSR in that case is of the ratio of the circumferential or "tangential" speed of the VAHT at maximum radius to the incident wind speed.  Every blade moves at or near this speed.  The ratio you are talking about is the ratio of the component of this speed at some point along the blade's trajectory in the direction of the incident wind to the incident wind speed (well, maybe the inverse), which is a different animal entirely.  Why not give it a different name to avoid confusion?  Or better yet, why don't you just deal with the apparent wind at each point in the rotation?

"The horizontals struggle, in other words, to keep their TSRs high ..".  They're not struggling, they're just obeying the physics.  One could say as tit for tat for your VAHTs, for instance, that when a blade is moving upwind it must struggle as the component of lift in the direction of motion approaches zero at the halfway point, the point of maximum apparent wind, while the drag reaches a maximum.  Such nebulous and disparaging statements serve no useful purpose except to make your motives suspect.  I suggest you train yourself to just stick with the facts.

[IntegEner]

See the comment under the nearby post above titled "Aerodynamics".

AVC, www.integener.com