I have played with the idea of designing a prop which incorporates ultrasonic cavities to produce bright water. But, the modeling is beyond my capabilities. If it can be shown to the boat owners that such a prop would generate more thrust by breaking up the cohesion of the water just forward of the blade (as a ultrasonic cavity should), the owners would have an economic encouragement to retrofit.
Again, I have no way to go forward with the idea. On Wed, Apr 27, 2011 at 7:50 AM, Mike MacCracken <mmacc...@comcast.net>wrote: > Another approach to the bubble generation effort, and one Russell has > suggested, is to take advantage of existing ships (of order 1000 to 10,000 > commercial ships at sea on a given day) and to put bubble generators on > them—perhaps doing so in a way that reduces their hull friction to make up > for power of bubble generation. Indeed, lifetime matters, but that depends a > good bit on bubble size, and extrapolating from big bubbles in a present > ship’s wake must be done cautiously. > > Using commercial ships is also an approach that could be used for CCN > generation as well, again depending on lifetime, etc. Indeed, there are > areas where no ships go very often, but commercial ships would seem a fine > starting approach. > > Mike > > > > On 4/27/11 10:14 AM, "Michael Hayes" <voglerl...@gmail.com> wrote: > > Thank you both for the insight. > > Yes, I do now recall the dual boat tether concept and I have some working > back ground in towing a long array of gear. From a pilot's point of view, I > can see an advantage of the dual boat/tether over the towed array. In that, > turning would be easier as well as being able to "lay out" a broader path > than a towed array. > > The need for a sail boat to tack back and forth into the wind does > seem challenging with a tether between the 2 boats. But, I can see how a > spring line rigging could adjust for any lag between boats in that type > of maneuver. The symmetrical hull concept is interesting in that I have > never considered a sail boat being able to "immediately" reverse direction. > > I personally would like to play with the idea of modifying the bright water > injectors along the tether to act as a "bow truster" type of directional > control for the tether. That may help in overall control of the > configuration. > > The recommended bubble diameter is .002mm. I can only see ultrasound > providing that type size for a high throughput operation. I believe a table > top experiment can possibly be done using the parts from an off the self > ultrasonic humidifier and deep well pump. Measuring such small bubbles is > something I have not studied yet. > > I did read in the paper Dr. Caldeira offered of observations of long lived > bubbles through possible contamination of a natural surfactant film. Yet, I > don't think the nature of the surfactant was mentioned. I refer to the first > page 2nd section > https://docs.google.com/viewer?a=v&pid=forums&srcid=MDE0NTY3NTk0NzY2MTMxMzQ4MjEBMDA1OTY0NDQ3MDgzNzU0NTIwODkBQkFOTGtUaWtZQ0pLSmJ2UzFRdFAzbmFrTHZkUTl3ay1kd0FAbWFpbC5nbWFpbC5jb20BNAE&pli=1 > > > Well, again, thank you both for the feed back. I will spend more time > thinking about this. > > > On Wed, Apr 27, 2011 at 5:29 AM, Andrew Lockley <and...@andrewlockley.com> > wrote: > > Stephen, > > This technology is already used for towing hydrophone streamers in geophys, > but it doesn't work quite like you suggest. There's no need for two boats, > and instead there's a paid of towed hydrofoils behind one boat, with the > support line tensioned between them. The low mass of the hydrofoils means > that there's no real shock on the cable in rough seas. The bubble > generators would be strung out on streamers behind this towed line. > > The bubbles would be distributed by a number of 'birds' which are depth-set > from the control room - just like the hydrophones are currently. > > To get good saturation with bubbles, I suggest that they'd need to be > delivered at a variety of depths - but whether that's worth doing depends of > course on the lifetime. No use dropping them ten metres down if they don't > last long enough to mix or rise. > > A > > > On 27 April 2011 13:05, Stephen Salter <s.sal...@ed.ac.uk> wrote: > > Hi All > > Michael Hayes asks about how bubbles could be deployed. > > One possibility would be for a pair of wind-driven vessels to sail side by > side at, say, a kilometre separation, attached to each other by a buoyant, > streamlined tether. > > The chord of the tether would be about 100 mm. In plan it would form a > catenary with a generous bulge to reduce the tensile load. The nose of > tether would contain a strong Kevlar or carbon tension member. Behind this > would be a number of high-pressure air-lines taking very well filtered air > from each vessel to a porous strip near the nose of the foil section and > running the full length. The drag of the tether would be reduced by the > bubble layer on the underside. > > The tether would have to be elastic enough to follow the curvature of the > wave slope. In most sea states this is surprisingly low but elasticity can > be increased by running the tensile member in a series of S shapes. > > The vessels need power but could generate this in the same way as suggested > for the cloud albedo project. Indeed it would not be difficult to design a > dual purpose vessel which would change mode according to cloud conditions. > It would be convenient if the vessels were symmetrical fore and aft so that > they could tack by going into reverse. > > The design does need information on bubble life and the best bubble > diameter and I would be most grateful for any advice on this matter. > > Michael mentions the Dracone project. I worked on this in a very junior > capacity in 1960 but a kilometre wide bubble wake would be cheaper if the > bubbles can last long enough and less of a risk than a Dracone that got > loose. > > Stephen > > Emeritus Professor of Engineering Design > Institute for Energy Systems > School of Engineering > Mayfield Road > University of Edinburgh EH9 3JL > Scotland > Tel +44 131 650 5704 <tel:%2B44%20131%20650%205704> > Mobile 07795 203 195 <tel:07795%20203%20195> > www.see.ed.ac.uk/~shs <http://www.see.ed.ac.uk/~shs> > > > > On 26/04/2011 23 <tel:26%2F04%2F2011%2023> :21, Michael Hayes wrote: > > Please help me understand the mechanics of Bright Water deployment. I have > spent many months living on the Bering Sea (in winter) and have piloted > 150ft fishing vessels in that area for countless hours. I have watched the > sea continually produce white caps for as far as I could see for days and > weeks at a time. How can a practical, cost effective and meaningful use of > bright water be deployed which comes even close to .0001 percent of the > natural production of white caps? The energy and equipment needed to cover > any meaningful amount of the sea is difficult for me to comprehend. > Outfitting fishing fleets with the needed equipment and paying the boat > owners to run the gear is possible. But, we are only talking about a bright > water wake which lasts for only a short distance...at best. > > Designing autonomous platforms specifically for the mission may be > possible, but, one storm could beach every single platform within a few > hours. Who and how will they be collected and sent back out? This, from a > seaman's point of view, is difficult to see as being practical. I have > studied the concept though what has been offered here and through other > links. The mechanical challenge of producing such small bubbles is > interesting and I have even spent time thinking through the possible use > high throughput ultrasonic injectors. But, I still come back to the > questions of; 1) how can bright water be practically deployed? 2) How can > the investment be justified when the wide area effect is so tenuous? 3) > Would not reflective large surface rafts provide a more cost effective long > term overall result? > > There is the option of a reflective form of the Dracone Barge as a useful > way to deploy large area ocean surface SRM. " > http://en.wikipedia.org/wiki/Dracone_barge. > > If such barges were deployed in large numbers a large area rafting system > could be secured in needed areas and moved as the season changes. With small > desalinization pods attached, we could have not just have low cost/long > term/flexible ocean surface SRM but a nice supply of needed fresh water. > Sell the fresh water and buy more bags!!!! > > I ask your help in understanding how bright water can be a competitive form > of SRM. > > -- *Michael Hayes* *360-708-4976* http://www.wix.com/voglerlake/vogler-lake-web-site -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
