The Cyclonebusting post got more attention than I expected. Patrick aka “Cyclonebuster” himself arrived. It turns out his “tunnels” are short relative to their length, so there is some hope that some flow will pass through the item. (I’m still not very hopeful that much will pass through because of the number of bends, screens, venturi etc. But, the amount may not be too close to zero. ) Still, Patrick is game and willing to do experiments. However, he wants to know which experiments might demonstrate his notion will work. (Recall, at this blog, we are focusing the flow through the pipe aspect rather than mixing afterwards.)
I’ve suggested a little experiment Patrick can do to show us how much water will flow through his system. ( The full analytical problem is more difficult than one might thing due to the boundary conditions at the exit of the pipe, which include flow.) The experiment I propose focuses solely on the issue of flow in the simplest possible case, omitting the complications of stratification, different velocities at the top and bottom, hurricanes passing over head, and other complicating features.
The test requires a boat: Patrick has a motor boat. He has a test rig. Ideally, this test rig will mimic the internal geometry of his proposed system including the venturi and something to imitate the turbine and all bends. If it doesn’t include these features he should tell us.
In this experiment, I propose that Patrick lay his test rig horizontally in the water along side his boat but far enough to be outside the boundary layer of the boat and outside the region where he can see noticable waves induced by the boat. The test rig should be immersed at least 20″. He may need to immerse further because it’s important to have no ripples formed on the surface. (The 20″ criteria is different from the ripple criteria. So, under no circumstances do this with the test rig too close to the surface.)
Looking down into the water, the rig will look like this:
His boat should be moving toward the left so that flow relative to the rig is left to right.
He should get his boat going at 6 mph (or there about) and then when moving steadily.
InkTest:
Once moving steadily, Patrick should perform the ink test. Use a small syringe to inject food coloring anywhere in the stream just so he can see if he can detect the trace of ink for more than 2 ft. (If the flow is too turbulent, the ink method isn’t going to work.)
If the ink is detectable, he should inject food coloring along the axis of the one inlet tube (example: the middle red dot on the left hand side of the straight tube in the image.) The food coloring should be injected at least 12″ upstream (this is 6 pipe diameters.)
The ink will highlight a streamline. You want to see if the ink goes into the tube, or if it splits an goes around.
Next, inject a little off axis– half a diameter would be good. Then, repeat almost a full diameter off axis. Patricks goal is to identify the area upstream that encloses streamlines that go in to the tube. If ink injected over every possible region over the diameter of the tube goes in, that’s great for his application. If ink in nearly streamline near the center does not enter, but splits in two, that’s very, very bad. I expect his results will be in between, but with a relatively small area permitting flow to enter.
(That said, I could be wrong, because his rig is fairly short compared to the diameter of the tubes.)
Now repeat the above at the other inlet.
Movies of this would be great!
Straw Test
After doing the ink test, Patrick should do the “straw” test. A straw can act as a stagation tap. (But it needs to be a long straw. ) He needs to bend a small diameter straw 90 degrees. (If Patrick has a tube bender, bending a 1/8″ tube would be perfect. Then, find a glass or plastic tube to glue over the top. You’ll want the vertical portion to be clear.) Once he has created his stagnation tap, he needs to immerse this somewhere far from his boat, away from the test rig. Face the opening into the flow. Show how high the water rises over above water level and if possible, measure this. This is height “h” in the image shown. (If his boat is going at 2 m/s, this should rise about 20cm, so he needs a long straw. He’s )
Next, he needs to immerse the tube in front of the exit of his test rig. The opening of the straw should be as close as possible to the exit– it can even be just slightly inside. Now, record “h”. If there is lots of flow through the test rig, this “h” will be similar to the one he measured away from the test rig. If there is very little flow through the test rig, this “h” will be much smaller.
This data will help us quantify the velocity of water flowing through Patrick’s system to the velocity of the boat. After that, we can do computations to explain how this affects power.
When Patrick reports back, we can contemplate other issues like stratification, screens etc. Meanwhile, everyone place your bets on how much water will flow through Patrick’s test rig.
Is the velocity of the Gulfstream varied with depth over the range of Patrick’s pipe?
EdBhoy– We don’t know. In his sketch , he shows velocity constant with depth. If it’s not, a followon experiment would involve figuring out how to vary velocity at two inlets.
The vertical rise is too short (If I understand the scale correctly) to demonstrate the problem that the straw test highlights: At some point the energy imparted by the motion is balanced by the additional weight of the water in the straw causing stagnation.
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IOW: I would not use 6mph to test this apparatus. It is true that you need to match Reynolds numbers to test the laminar/turbulent flow characteristics, but the wall losses aren’t his number one problem.
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A third ink test would be to squirt the ink actually -inside- the inlet. Yes, you’ve disturbed the flow getting the syringe there, but this should give an idea of what the water in the tube is doing. If there’s anywhere near 6mph flow, there will be a nice solid stream at the outlet and nowhere else. Or you’ll get diffusion-based slow leakage and no ink flow.
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I might simply the experiment to -just- the angled tube also. This is the crucial piece.
Alan–
I figure that drilling the hole to release ink inside would be troublesome. He can do the other test almost immediately with the test section he has. If any ink enters, it will come out the other end. If none enters, none will come out.
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Yes. The straw is a stagnation tube. The weight of the water balances the extra stagnation pressure.
In the vertical rise of the tube, the height of water above the free surface will be
1/2 V^2 / g = h.
where V is the velocity at the front of the stagnation tap and g=9.8 m/s^2 on earth.
6 mph is between 2 and 3 m/s. If V~ 2 m/s, the height of the water will be about 0.2 m or 20 cm. If it’s shorter, a little water will flow up. The exit velocity of the fountain will be less than 2 m/s due to flow losses in the tap, which are zero when there is no flow.
He’s already made the mock-up and shown at forums. So, I think it’s less work just to use it.
1) I think you need lots of runs at different velocities because you really aren’t doing fluid mechanics until you have enough data to present a pattern that can’t be explained.
2) I would also include a 3-foot leader and a 3/0 treble hook with a splash of neon tubing on the back end of the device just in case anything is biting.
Will there be a flow meter?
* http://www.safety-devices.com/adc_wind.htm
* http://www.google.com/products?q=Flow+TX+Plus&oe=utf-8&scoring=p&sa=N&lnk=next&start=10
* http://www.google.com/products?q=Water+flow+meter&oe=utf-8&scoring=p
(Watts’ hard-to-browse shop only seems to have a non-submersible wind flow meter)
Also, the needle talk makes it sound as if he’s going to reach down with a handheld device while trying to do everything else. Probably easier to have the whole rig mounted to a wooden frame which also holds a quart bottle of unsugared colored beverage (ie, KoolAid) connected to a thin pipe which is mounted in front of the pipe. Hardware and hobby shops have small metal pipe.
I remind Patrick to try the whole rig in water at home several times to debug it, to avoid hours of wrestling with objects over the side of a boat. Also check the color and clarity of that lake’s water before choosing a dye.
I would have beer in the boat.
Scooter– the bent straw measures velocity. This is a “proof-of-principle” experiment, but incomplete. I’m looking around for kitchen items to explain the problem Alan is describing. But if Patrick does the experiment I suggest, we can do calculations that include both the frictional losses and the problems associated with the weight of the water. (Colder water is heavier than hot water, so part of that dynamic pressure from the jet stream needs to off set this extra weight. I’m looking for a) salt, b) food coloring, c) a glass pitcher and d) a turkey baster. I will make a youtube video.)
EdBhoy (Comment#14873) June 19th, 2009 at 10:34 am
“Is the velocity of the Gulfstream varied with depth over the range of Patrick’s pipe?”
Yes, you might estimate 1000 ft to be around the half-velocity depth. Also, the difference in potential density is about 6.5 kg/m^3. I assume this is important, since the point of Patrick’s device is to accomplish vertical mixing.
But if we want to know if there’s any flow at all even in unstratified water, then I think the stream lines will be a good start.
Lucia, the simple test for what I’m still stuck on is a straw and a bathtub of water.
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No, you can’t consistently reach 6mph by waving the straw around in the water. But all you have to recognize is “Hey, if I’m only moving a little bit, then it doesn’t come out the top!” Along with the more detailed “Hey, the water coming out the top isn’t moving as fast as ‘the flow.’ IOW: literally your straw test.
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-Thinking- about those, and the implications for the “Black Box” and “IN=OUT” reasoning we’ve got should be convincing.
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The other very simple experiment I couldn’t interest Patrick in involves a siphon. When you have a -working- siphon, you’re starting with the flow in the tube that Patrick expects. If I’ve got flow into the tube, whatever’s going on outside the tube is basically irrelevant. There’s nothing in his argument that changes when you lift the outlet of the siphon. So why does the water stop flowing?
Alan– Oh. Well… there is another problem associated with the density change from the top to the bottom of the ocean. I thought it was part of your point. I’ve got color water, colored sugar water. I’ll be showing what I’m talking about.
Are you crazy? Experiments? Measuring flow velocities? Who’d trust them anyway? Get a computer and write a model, let it run with a wide variety of startup conditions, a reasonably unprecise resolution and compute the mean results, for gawd’s sake. (Experiments!!! tsk tsk tsk)
Experiments on boats with beer can be fun. If I lived in Alabama, I’d join Patrick on the boat and help take photos.
Seriously – the two effects (flow velocity and lift) can be tested seperately in order to overcome the problem with different velocities at different depths. For the first experiment one would just have to take a pipe with appropriately downscaled dimensions and measure flow through the pipe at various speeds (like from a boat). Rather than measuring directly, I’d propose measuring the time it takes for a floating object to make it through the pipe compared to an identical object beside the pipe. The lift can then be tested by pumping water through the pipe at the rates measured in the first step (independently from the difference in flow velovities at the upper and lower inlets). Creating or at least calculating the effect of the temperature and specific weight differences of the water at the inlets is probably the most tricky part.
Thanks for all the tips. This will be a fun experiment. BTW from what the National Hurricane Center told me about 15 years ago the flow is the same even at depth. Also the colder denser water at depth carries with it more Ke with than the warmer surface water.
Also the colder denser water at depth carries with it more Ke with it than the warmer surface water.
And a heck of alot more pressure.
Patrick–
With respect to inducing flow in the pipe, the fact that the deeper water is colder and denser is a problem, not an advantage. I’m going to try to set a little demonstration for this.
I understand it will be harder to move but I still think that there is enough pressure differential to do the job. I think we would have to go much deeper untill stagnation around 3000 feet. The bottom Tunnel inlet is only 1000 feet at depth and well above the 3000 foot level.
Patrick,
Could you explain what you mean by “I think we would have to go much deeper untill stagnation around 3000 feet”?
You may have runs some numbers, but I don’t know what you are trying to communicate here.
The longer the tube the more friction there is so it can’t be to long or friction would stop it.
What do you come up with?
Patrick,
The colder, denser water at depth carries less KE because it is moving more slowly. And even if it were at the same potential density, the increased pressure would be completely offset by the difference in potential energy due to its lower position relative to the earth.
Patrick
Getting my head around your theory of why this is going to lift cold dense water to the surface is not easy. If the water at your inlet is 6kg /m3 denser then the extra weight of the water is likely to stop the water flowing up the tube very quickly.
However you have to try to isolate individual variables if you are to get better understanding of whats going on so forget about density differences for the moment and use the boat experiment as a starting point. I have run experiments offshore in the past and it is always more difficult and time consuming than you expect so allow for lots of time.
If you ever prove the physics behind this your biggest problem will be connecting your pipe network to the earth so that it doesn’t just get swept away. This is a considerable issue for deployment of marine current turbines which are placed near to the shore in shallow water and preferably sheltered from the worst of the weather. The depth of water off the continental shelf and the severe weather will make the problem orders of magnitude more difficult to overcome.
By the way, why do you need the horizontal pipe? Are you hoping to funnel the water through the horizontal pipe to increase its velocity?
If you are not accelerating the water in the horizontal pipe does it matter where the inclined pipe discharges as long as it is near the surface?
My this is fun! I’m sitting here thinking of all sorts of experiments with hosepipes.
We need to look at how oil wells are attached to the sea floor.
lucia (Comment#14882) June 19th, 2009 at 12:12 pm: I wasn’t proposing a flow meter to determine velocity outside the pipe, as what is of interest is whether there will be any flow inside the pipes. There will be some flow through the horizontal pipe, reduced by backpressure due to friction and the turbine obstruction. There will be a small amount of suction on the downward tube due to moving fluid, but I doubt enough to pull a significant amount from a thousand feet down (if that suction is important, Patrick would have studied flows and used pinching or flaring to enhance it).
Scooter–
Yes.
If the inlet of the bent straw is placed directly in the exit of the pipe system, it will detect the stagnation pressure at the pipe exit. This is flow coming from inside the pipe, not outside the pipe. In this problem, if there is any appreciable flow inside the pipe, the flow with be turbulent inside the pipe. So we can estimate the flow rate as approximately Q= VA where V is the measured velocity and A is the area. If the flow is laminar, we can correct for the profile (assuming we believe Patrick can place a probe perfectly. But anyway, if the flow inside the pipe is slow enough to be laminar, this system will basically not work. In a 2″ pipe, laminar flow happens for flow velocities below roughly 5*10^-2m * V/ 10^-6 m^2/s =2000, which is V= 2 mm/sec. )
The purpose of this particular geometry is to find out the importance of the flow resistance (due to frictional effects.)
I’ve got some oil and water rigged up to talk about the effect of density differences. I’ll be blogging about that later.
I don’t know which is going to be more important in this problem because a) I don’t know how density varies with height in the gulf stream and b) I don’t know the magnitude of the frictional effects. Each individually may be enough to prevent flow, but I’m not sure. I suspect oliver will be able to provide me the density info after I blog about that effect and explain the theory as it applies to the pipe problem. So, after a few goes around, we will either convince Patrick this won’t work or we’ll all change our minds and conclude that, contrary to our intuition, it could work. (I think, based on back of the envelop computations that it won’t work when we combine the dificulties. But as I said, I don’t actually know the frictional losses and I don’t know the how density varies as a function of elevation in the gulf stream.)
PatrickC,
My prediction for your outdome is this: The vast majority of whatever energy the water at depth is carrying is going to be used lifting it in your manifold.
hunter– I suspect you are correct. But to show Patrick, I need numbers. Ideally, I can show both the frictional effects (assuming there is some flow) and the gravitational effects, which I need to prove to him exist. (I’ve got oil and colored water pictures coming!)
In principle there will be some flow through an upward inclined pipe, as evidenced by natural ocean upwelling.
Kinetic energy can be extracted from a flowing fluid. e.g., wind energy or tidal flows. e.g. see: Tidal current energy resources and power production by Tidal In-Stream Energy Conversion (TISEC)
See 1.4 Overview of Tidal Stream Energy Conversion Methodology
Power/Area = 0.5 * density * Velocity ^ 3.
6 mph ~ 2.68 m/s (at 1 mph = 0.45 m/s)
http://www.csgnetwork.com/h2odenscalc.html“>Density calculator
At 50 F or 10 C, seawater density is 1030 kg/m3
At 90 F or 32.2 C, seawater density is 1024 kg/m3
assuming 39000 ppm TDS.
(Note 90 F or 32 C is high for tropical surface water. Recommend using 81 F or 27 C as more achievable.)
This suggests a potential power of 1 kW/m2 for a turbine to extract energy from the gulf stream. When conversion losses are accounted for, about 40% of this might be achievable.
That potential power then needs to overcome the density difference in pushing the cold water up to the surface.
However, as Lucia points out, the bends and friction along the pipe can reduce a major portion of the energy potential.
In Ocean Thermal Energy Conversion (OTEC), about 2/3 of the (small) potential power is consumed in overcoming hydraulic losses.
See OTEC at NREL, and
OTEC News
For those interested in understanding the underlying physics, note that there is also a salinity/temperature driven phenomena of the “perpetual salt fountain” that can drive a natural flow upward. e.g. see:
Numerical Simulation of Upwelling Flow in Pipe Generated by Perpetual Salt Fountain
Tetsuya SATO et al. 16th Australasian Fluid Mechanics Conference
Crown Plaza, Gold Coast, Australia, 2-7 December 2007
lucia,
I was on the operations side of project management, not the technical, lol. But this is a fun excercise. There is a great deal of energy in existence all around us.
Just for example, check out cavitation heating of water and other fluids:
http://peswiki.com/index.php/Directory:Cavitation_Heaters
There are all sorts of internet rumors about this well established clever trick.
Getting that energy to be available for our use in meaningful amounts or forms is and will be the great challenge. I am at heart a romantic optimist, and believe that we will be successful, at some point in the not-too-distant-future.
Patrick Cyclonebuster (Comment#14896)
While you are experimenting, may I suggest testing the simpler configuration of just the angled (Z shaped?) riser without the horizontal surface inlet.
That configuration would make alot more sense to me and would be much more easily modeled.
You might get even get some results that you can compare with published results.
If you can use long curved bends, you will likely get even better results than using sharp 45 deg bends.
David L. Hagen (Comment#14915) June 20th, 2009 at 9:32 am
It isn’t clear that this mechanism is very important to natural ocean upwelling. Large upwelling events can be driven by divergent flow in the surface layer (Ekman pumping), but this is about satisfying continuity, not due to any natural tendency for water to flow uphill.
Turbines directly in the flow might not be such a bad idea, but it’s much different from also mixing deep water from 300 db to mitigate hurricanes.
Maruyama et al. 2004 have measured the flow in an salt fountain experiment using pipe 280 m long, but at 212 m/day (!) of flow I don’t think it would be stopping hurricanes while driving turbines at the same time.
Show where there is upwelling without the surface water being pulled away, or where no obstacle is forcing the upwelling. Ocean currents are generally wind driven. Look at the origin of the current which is blown westward to South America, and what then happens to it.
David–
Yes. In principle, there is lots of energy that might potentially be converted into electricity. But the question here is: Can the system Patrick describes extract any significant amount of energy? Can it generate electricity efficiently relative to other methods? Can it bust cyclones at the same time?
If the goal is to generate electricity, I suspect it would be more efficient to just build the equivalent of underwater wind turbines and forget the “tunnel” part of the idea. The tunnel is just going to induce unnecessary flow losses at the entrance and exit, and it’s going to require quite a bit of civil engineering to hold in place.
If the goal is to bust cyclones, I suspect it’s best to leave the turbine out of the tunnel. (Whether or not the cyclone busting will work at all will depend on some information I’m hoping Patrick will provide based on the post I just added.)
While out enjoying the weather here on a visit to San Antonio, I recalled what I was told when I was a young lad on the Gulf Coast:
Water does not flow uphill.
I think this annoying limitation is why, no matter how neat PatrickC’s ideas are, and they are very neat, they will not result in any great break throughs.
Now there is a place near Santa Cruz, Ca, called ‘The Mystery Spot’
http://www.mysteryspot.com/
And they do some amazing things regarding gravity and moving things uphill,
http://www.youtube.com/watch?v=X83mJ35HOwM&feature=player_embedded
But from my experience, it only works at this very spcecial ‘spot’.
Enjoy,
David-
The salt fountain issue is cool! However, Patrick’s system can’t use that method of inducing flow because the salt fountain requires heat transfer across the pipewalls! In the salt fountain they are specifically drawing up less salty water. It because less heavy as it travels up and warms.
But even if the water at the entrance of Patrick’s cyclone buster has less salt than the surface, Patrick’s cyclonebuster can’t permit heat transfer across the walls of the pipe. If that heat transfer occurs, he can’t cool the upper surface much. The water coming out at the top of the pipe would already be warm!
I’ve been assuming zero heat transfer across the pipewalls when trying to figure out if this thing can work.
David L. Hagen (Comment#14915) June 20th, 2009 at 9:32 am
In principle there will be some flow through an upward inclined pipe, as evidenced by natural ocean upwelling.
Show where there is upwelling without the surface water being pulled away, or where no obstacle is forcing the upwelling. Ocean currents are generally wind driven. Look at the origin of the current which is blown westward to South America, and what then happens to it.
See Charleston Bump:
http://oceanexplorer.noaa.gov/explorations/islands01/background/islands/sup11_bump.html
The “mystery spot” is an optical illusion theme park where they present it as “ooh spooky” instead of “here’s how it works”.
Lucia,
Maybe my old friends can help
http://www.rollinghillsresearch.com/
hehe, long ago I worked at a water tunnel company.
Anyways, if you like I can write them a short note for old times sake.
steven–
It’s up to Patrick. But I think based on density difference charts Alan posted, the whole idea my be trumped by density differences.
steven mosher (Comment#14978)
June 22nd, 2009 at 12:45 am
Lucia,
Maybe my old friends can help
http://www.rollinghillsresearch.com/
hehe, long ago I worked at a water tunnel company.
Anyways, if you like I can write them a short note for old times sake.
LOL! Wouldn’t be ironic to test a water tunnel inside a water tunnel?
Ha patrick, I worked at water tunnel company. Different department but we got to watch all sorts of cool experiments on vortices. the inlet of your tube might make for some interest flow viz experiements.. or just a fun day in the lab.
steven mosher (Comment#15115)
June 24th, 2009 at 2:14 am
Ha patrick, I worked at water tunnel company. Different department but we got to watch all sorts of cool experiments on vortices. the inlet of your tube might make for some interest flow viz experiements.. or just a fun day in the lab.
Can you stratify the horizontal flow to be that of what is in the Gulfstream?
What did you come up with Lucia about the back end pressure?
Patrick– There is nothing to come up with about back end pressure.
The tunnel outlet has a more negative pressure as the water flows past it then it would normally have than if the flowing water stopped.
Just like an eductor works.
A water eductor or water dredge is a tool used by underwater archaeologists to remove sediments from an underwater archaeological site. Airlifts may be used for the same purpose.
Archaeologists preparing a water dredge on a shallow siteIt consists of a large bore straight tube to which is attached a hose pipe through which clean water is pumped. The Bernoulli effect from the flow of pumped water causes suction at the mouth of the dredge. Water and sediment is sucked from the excavation site and released from the far end of the tube. The tube can be made of any rigid material such as steel or plastic. The diameter of the tube depends on the power available from the pump and whether delicate work is required.
In the hands of a trained archaeologist, the water dredge performs the same function as a wheelbarrow on land. It is used to carry away sediments, not to dig holes. The archaeologist dislodges the material using a trowel, brush or by making a fanning motion with the hand to cause a current to dislodge sediment. The archaeologist can also place overburden material directly into the mouth of the dredge. As the water dredge will remove particles held in suspension in the water, provided it is used correctly it will improve visibility in the immediate area of the excavation. Careful use of the water dredge ensures that artifacts can be recorded in context and features and stratigraphy can be studied.
Using a water dredge or airlift, the underwater archaeologist has an advantage over terrestrial counterparts, as the spoil is removed without effort and without needing to be transported across other parts of the archaeological site.
Where there is a possibility of small artifacts being missed because of poor visibility, a trap may be used at the outlet so that the lifted sediment can be filtered.
Water eductors are also used by marine treasure hunters to suck sediments for filtering for buried artifacts. Using the water dredge to directly suck sediments means that archaeological information on context and stratigraphy is not recorded.
Patrick–
Your system is nothing like an eductor. Here is a picture of an eductor pump:
http://www.pumpsofoklahoma.com/jet-educator-systems
Your design does not have a pump pushing high speed fluid through the nozzle with labels (1) and (2).
This FORCE must also be used calculated at the back end!
It is not exactly like one but it works like one.
The pump is the Earth and the fluid is gulfstream flowing past the exit!
Remember the tunnel is anchored to the sea floor!
Just as the Ke at inlet would cause a rise in the water column so would a vaccum at the tunnel outlet. Did you calculate BOTH forces?
Just as the Ke at the tunnel inlet would cause a rise in the water column so would a vaccum at the tunnel outlet. Did you calculate BOTH forces?
Good night I’ll let you sleep on it.
I hope you all learned something from the BLACKBOARD tonight.