Speculation, and other folly!
Locked
 
|
John Dabiri is not a Caltech aerodynamicist, and has never published on wind energy, propellers or rotors. My thesis was on wing theory at that institute, I taught there for many years, and have published many papers, monographs and bits of books on the subject of wind turbines, including a lot of stuff on design of rotors and arrays. I don't know what he knows, but I do know sumpin! But validity depends not on pedigrees but results!
The article in Physics is pretty bad, for example, contrary to the author's statement, prop turbines do not shed vortices, but annular vortex sheets, with a lotta turbulence, a very different animal, that I have often analyzed, tested and measured in wind tunnel and field. I was concerned at his naive statement that the power increases because the rotational speed increases. It's elementary dynamics that this is not necessarily so. The power is the product of speed and torque, and for many turbines the power reduces as the rotational speed is increased! In fact, in design studies, we often would feather, causing a unit to speed up and reduce power output. For example, a prop anemometer spins very fast, extracting no energy from the wind, at essentially zero torque (except bearing friction). If it is braked by a motor, then the spin reduces as the power production goes up. I dunno what John's paper is about, haven't read it. It is always good when an outsider introduces a new idea into a field. So I'm looking forwards to hearing. I am amazed at folks tenacity to an idea that they don't even understand! But like the sound of, I presume! I have no opinion on the subject, because I haven't seen the paper. When I receive same, I'll discuss for Friamers. I don't want to waste folks' time on conjecture.
Peter Lissaman, Da Vinci Ventures ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org |
|
|
Hi,
Steve wrote: > SimTable (tm) is always in need of more > notional models to demonstrate it's utility across a wide variety of > domains, especially those likely to be involved in public-policy > decisions. Also, the SF Complex art crowd might be interested in looking at interactive exhibits using fluid dynamics algorithms. Here are some cool videos of vortex sheets and vortices, etc. http://media.efluids.com/galleries/vortex?medium=625 http://media.efluids.com/galleries/vortex?medium=578 http://media.efluids.com/galleries/vortex?medium=64 I recently had the opportunity to work on a OpenCL compressible gas dynamics code and was immediately struck by the beauty of these simulations. I'm neither an artist or an applied math guy, so all I could do is make it go fast... A dollar a gigaflop these days with PS3s and GPUs, etc. http://sourceforge.net/projects/hypgad/ Marcus ============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org |
Re: Speculation, and other folly!
|
|
In reply to this post by plissaman
It seems that this Dabiri chappy gets around: he was referenced in The Economist a couple of weeks ago in an article "The Skeleton of Water - Lagrangian coherent structures" for his work on the hunting behavior of jellyfish
-- Robert On Sat, Nov 28, 2009 at 11:33 AM, <[hidden email]> wrote:
============================================================ FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org |
| Free forum by Nabble | Edit this page |