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Natreely

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Fish-way using low head hydro turbine
« on: March 16, 2016, 04:30:23 AM »
Hi all,
Thanks to all who give time and knowledge to help here, as have found much practical information here in the past.
Now on topic:
Being a keen recreational fisherman and liking to think of myself as a conservationist (aren't we all?), I've done a lot of research into fish passes / ways / ladders and low head hydro. While a well designed Archimedes screw generating power, can safely pass fish in the downstream direction, a functional fish-way is still needed for upstream traffic. Then my attention was drawn to a system developed in Austria, patented 2009 so relatively new for hydro technology, which the owner calls a Gravitation Water Vortex Power Plant or GWVPP, and claims to safely enable fish passage in either direction. On his website there is a fish monitoring study summarised, which successfully recorded fish passage in both directions. The major problem we have (that is "Down Under" in A&NZ), is that none of the indigenous or endemic fish are fast & strong swimmers, so they wouldn't be able to cope with the 110 Watts per cubic metre in the Austrian designed GWVPP, so not surprised to note that the fish that passed upstream through the GWVPP are all Salmonids, which are all fast and strong. That means they not only have burst speed but also stamina. So could the Austrian design be adapted for less W/m^?. The patent owner said yes, if you use at least a 6m diameter rotation tank. Well that is nowhere near enough "inflammation" to be able to compare costing with a Vertical Slot Fish Way or VSFW, which basically costs upwards of AU$150,000.00 per vertical metre. Next: more research and more research, finding that enough data is out in public now as some scientists have been working diligently!
Please be patient with me and I'll post some details of what we now know as fact, and not just speculation. Then a question...
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #1 on: March 16, 2016, 04:56:49 AM »
The following six points are a summary of known facts copied from [3] which is really from [2] and other research combined.
1.   The water surface profile of the vortex can be modeled mathematically and predicted accurately. 

2.   Optimum vortex strength occurs within the range of orifice diameter to tank diameter ratios (d/D) of 14% - 18% for low and high head sites respectively. 

3.   The vortex height varies linearly with discharge. 

4.   Linear correlations for H v Q can be scaled accurately to prototype size using 
the Froudian Model to be used as a design chart. 

5.   Maximum ideal theoretical power output = ρgQHv (Hv = Height of Vortex). 

6.   Maximum hydraulic efficiency should arise when the impellor velocity is half 
that of the fluid velocity.

[1] Power, MacNabola & Coughlan 2015, Trinity College Dublin
“A Parametric Experimental Investigation of the Operating Conditions of Gravitational Vortex Hydropower (GVHP)”

[2] Mulligan, S. & Casserly, J. 2010 Final Year Civil Engineering Project, Institute of Technology Sligo 

      “The Hydraulic Design and Optimisation of a Free Water Vortex for the Purpose of Power Extraction”

[3] Mulligan, S. & Hull, P Masters in process Civil Engineering Project, Institute of Technology Sligo 

   “Design and Optimisation of a Water Vortex Hydropower Plant”

Paper [1] provides some limited help in blade design, but little else as they completely overlooked the 2010 paper [2].

… So how do we accurately calculate the dimensions of the rotation tank and its’ orifice, to allow fish through in an upstream or downstream direction? There are more than 12 working GWVPPs that we can reference output figures and efficiency charts. So added to the research paper findings we have enough data to put together, to add up to something useful…
Having never used an MS Excel spreadsheet before, this was a trial of patience, to group all the facts computing something roughly accurate.
The result seems credible. Can the Excel attempt be posted for suggestions, constructive criticism, or maybe something glaringly obvious that I’ve overlooked? Any Excel gurus on forum?
My motive is altruistic (now being a full time volunteer), having a couple of sites that would work, but need to be reasonably sure of the design before presenting it as a viable option to the local environmental experts.
Hoping this attracts some expert interest.
Nat.
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #2 on: March 18, 2016, 12:22:32 AM »
We are really designing from the perspective of fish passage in both directions, so here are some research results that will influence design in Australia and New Zealand. This really demonstrates how important is the orifice size under the turbine.
Eel Migration in New Zealand
From “Non-fishing Mortality of Fresh Water Eels (Anguilla spp)” in the New Zealand Fisheries Assessment Report, June, 2005
Migrant female longfins range from 800mm to over 1500mm in length and males from 500 to 700mm. Migrant female shortfins range from 500 to 1000mm and males 350 to 550mm (Todd 1980). In comparison to most other freshwater eel species around the world, adults of the two main freshwater eels present in New Zealand are large. The potential for injury or mortality while passing over barriers and through turbines is therefore greater in New Zealand than elsewhere.
Size, Velocity and turbulence
From “Sea To Hume Dam Final Report” of the Murray Darling Basin Commission April 2008
At the remaining 14 low weirs, the MDBC determined a need to pass a wide size range of fish including about half of the sh between 20 and 70 mm long (or all those over 40 mm long) and all between 90 and 600 mm long, with a maximum size criterion of 1000 mm for Murray cod (Maccullochella peelii peelii; Barrett and Mallen-Cooper 2006). A vertical-slot fishway design was selected, as it operated over a wide range of river levels, with a low gradient (1:32), low water velocities (maximum 1.4 m/s) and large pools with low turbulence (40 W/m3; Barrett and Mallen-Cooper 2006).

We will summarise some design conclusions from this in the next post.
Rgds, Nat
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #3 on: March 19, 2016, 07:30:58 AM »
Design Conclusion:
The minimum orifice diameter would need to be 1m with the turbine having 4 blades or less to pass Murray Cod of 1m length (as they are deep in girth size) or large eels in NZ (as they are slow). Prescribing a minimum orifice diameter will also make sure that the velocity will be less than 1.4 m/s. Also this will give a wider tank diameter because of the efficiency ratio, thus contributing to less than 40 W/m3. Of course, the higher the efficiency of the turbine, the less W/m3 remains. The turbine rotation will be between 10 RPM and 30 RPM, but as yet we do not have adequate data to link the RPM to the flow rate & head height, but hopefully this can be added to the spreadsheet later.
NB. The W/m3 figure results from Hydraulic power (100%) minus the mechanical power %. Like the Betz limit with wind turbines, hydro turbines have the same issue of getting the water that has spent its’ energy out of the way. This efficiency generally follows a bell shaped curve, some turbines having a flatter curve than others. Then to arrive at a prediction of electrical output, we must multiply the figure by the percentage that results from other inefficiencies like gearing / bearing friction loss, generator loss and line loss. Given that outputs now being recorded, range from 50% to 65% total efficiency, considering they are designed for power output with fast swimming fish traffic, then it is not unreasonable to expect that the highest total efficiency will be 55% but in the near future more likely to be 45% - 50% when designed for slow swimming fish. Still, this is not a bad output for 0.5m to 1.5m head height.
Still working on this spreadsheet:
Do you think I need an introduction to Mr Bernoulli and Mr Reynolds for the input of their numbers or, does someone have a simple formula we could use to mesh RPMs into the spreadsheet? As in, at x head height with y flow rate = z RPM?
Rgds, Nat
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #4 on: March 21, 2016, 08:09:49 AM »
Firstly, sorry, we need to make a correction to the first post above:
Patents on this technology were granted in Austria 2003, 2010, 2012 and Switzerland 2007 and Germany 2010
Yes, we can still say, a relatively recent addition to the micro hydro list of options.
I’ll have to leave Mr. Bernoulli and Mr. Reynolds to the tender mercy of professional mathematicians. For now, we can take a simple route of approximation, being aware that this will render the results more coarsely rough, rather than just roughly accurate! Still it will give an idea of the ratio of gearing required, so to be able to combine with an appropriate generator…
RPM reasoning:
Within the core of a full air-core vortex, the rotational surface velocity can be much faster than the vertical velocity through the orifice. Then, (a) in this case it is not a full air-core vortex as the tail water level is above the orifice, with above that a suspended turbine. Then, (b) we are not just concerned with surface velocity but the average velocity having effect on the surface area of the submerged blades, both with push force and suction drag… Then I take it upon myself (gulp) to put a theory forward: The tip speed of the turbine shall be no faster than the maximum possible velocity through the orifice at the supplied volume, where the turbine diameter is no less than 1.3(Orifice diameter).
We’ll get this spreadsheet finished and posted yet!
Rgds, Nat
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King Solomon

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Re: Fish-way using low head hydro turbine
« Reply #5 on: March 22, 2016, 12:55:01 PM »
The MS Excel spreadsheet _FishwayGWVPP.xlsx
Work through inputting some different numbers into Tank diameter at top left, then you’ll quickly get the ballpark figures for the head height and flow range you have available.
Please could we have suggestions for improvement of this attachment. When in a technical aspect please include your source of the research and/or calculations by which you arrived at that point.
You may also find this 4.9Mb transcript to be an interesting read, particularly chapter 2 by Andreas Steinmann:
http://assets.hansgrohe.com/assets/global/Wassersymposium_2012_What_water_needs.pdf
Rgds, Nat
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #6 on: March 23, 2016, 01:08:51 PM »
Maybe, I've glossed over some things, taking it for granted that you can read my mind and arrive at my reasoning!!! Like...
Turbine Diameter due to Orifice diameter
Reasoning that people will hardly bother with a mechanically adjustable orifice, to increase or decrease the orifice diameter according to the flow rate. Therefore the designer will chart the mean flow rates from history, fixing on an orifice diameter that is going to be optimum or close to optimum for the most time. The area of faster rotational flow does not extend anywhere near one third the radius of the tank. Seeming more relevant to tie the turbine diameter to the orifice size, it is just inside and just outside the orifice circumference that the rotational flow is best to be in contact with the blades. Remembering of course that we must have room between the blades and through the orifice for the species of fish involved.
Please note that as mentioned below the spreadsheet, having decided on a fixed orifice diameter then to multiply by 1.3 to get the turbine diameter may not be optimal as we haven't yet found adequate research to connect the two together. Therefore if the optimal factor is less than 1.3 then the RPM figure will be slightly more. Otherwise if the same length of blade was curved tighter to the shape of the vortex, there would still be the same surface area in contact with less diameter of turbine, consequently slightly higher RPM. This effect on the RPM can be seen as the Turbine Diameter is adjusted at top middle of the spreadsheet.
Due to the shape of the vortex, the height of the blades doesn't need to be higher than 75% of the maximum head height or 80% if curved up, therefore saving turbine weight.
Even though this spreadsheet was done with slow fish in mind, the parameters of the conditional formatting are easily adjusted, to give the green light for the design specifications suited to your local species.
When significant adjustments are made to the spreadsheet we can reattach it here.
Rgds, Nat
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #7 on: March 28, 2016, 01:41:55 AM »
While rereading some of the research on blade experiments, it was noticeable that,
(a) Efficiency increases in extracting power from the water with increased blade area in contact with the water, in simple terms, more blades,
(b) Yet reaches a point very quickly that the extra blade weight putting pressure on the bearing counteracts the efficiency.
Then a Eureka moment, well, something clicked anyway... Why don't we increase the buoyancy of the individual blades so the turbine becomes weight neutral?
Having welded a few polymer things together before, we do find working with ABS relatively simple. A double skin in the submerged area with an air space enclosed and horizontal ribs to strengthen the blade, so how much air space is needed?
Firstly how much weight is involved in the turbine plus the shaft?
Working with a hypothetical 1.2m head height, 0.9m x 0.3m of blade submerged (allowing for some air core as it is a "critical" vortex), and using the online ASM Weight Calculator with 3mm ABS for the blade and 3mm wall 56mm OD ss pipe for the shaft... Gives us up to 7Kg for the shaft/brackets/bolts and 2.8 Kg per blade.
Then, for all the submerged square area an average of (AG = air gap B = buoyancy) 12mm AG = 3.2Kg B, 15mm AG = 4Kg B, 18mm AG = 4.86Kg B.
Now to follow through,
Where 4 blades is designed, 4.86 * 4 = 19.44Kg B minus the weight of  2.8 * 4 + 7 = 1.24Kg upthrust so reduce the AG slightly.
For 6 blades including a 15mm AG 4 * 6 = 24Kg B minus the weight of 2.8 * 6 + 7 = 0.2Kg upthrust.
Are we on the right track to increase mechanical power? Opinions???
Rgds, Nat
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Natreely

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Re: Fish-way using low head hydro turbine
« Reply #8 on: March 31, 2016, 08:03:54 AM »
In the above post regarding "Turbine Diameter due to Orifice Diameter" we mentioned mean flow rates.
Mean flow data should not involve extreme flow rates, either of drought or flood. So we need to make clear that this is not about an overall average. An "average" is when lines of data are added together then divided by the number of lines, but if this data includes the worst drought period in 50 years or a 1 in 50 year flood, then this is going to be terrible on which to base a hydro turbine's operating range. You may not want to even include the dip / peak of of a 1 in 10 drought / flood, but you decide where to draw the line.
Why do we need to draw a line through it, flattening the data?
In the 30yr+ design life of a good hydro turbine, extreme events happen less than 5% of the time, not so extreme events (but still not normal) happen less than 15% of the time. So while it is helpful to know major flood heights, so that the expensive equipment can be winched out of the way, we want to base the normal operation on what happens at least 75% of the time. On that long term chart cut off the peaks and valleys (draw the line), for flooded "drown-out" or below marginal generation level drought are not operational time anyway.
Having a roughly accurate operating flow range to design from is crucial for giving vortex heights, orifice diameter and therefore tank diameter, in fact for the GWVPP the design mostly depends on what flow is available. As a fish race 0.5m to 1.5m is a good head height. According to the research mentioned above, 255 litres per second only gives 0.4m vortex height so we couldn't expect much more than 300 W at that flow rate. For a vortex, the flow rate dictates the head, so even if you held back 1.5m head of water then opened the orifice, it would briefly have a faster flow rate then drain down to whatever vortex height the flow could support.
Some good advice on finding data for assessing your flow rate history can be found at the following thread:
http://www.fieldlines.com/index.php/topic,148642.0.html
Hopefully the flow of information will help both the swimming of fish and the flow of electricity.
Rgds, Nat.
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King Solomon

Natreely

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Re: Fish-way using low head hydro turbine
« Reply #9 on: April 01, 2016, 12:19:15 PM »
Yes we are serious in saying that 255 litres / second is very low flow for any low head hydro but...
Hypothetically saying that's what you have, with 1.5m of head height available. You just happen to own a concrete batching plant so the infrastructure cost is not going to be as huge as for most farmer Joe Citizens. So you put three 0.5m deep tanks one after the other, providing 3 x 300 Watts. Most high living people off-grid would say that a reliable 21.6Kw/day is not to be sneezed at. Well you do have the cost of three turbines, generators, wiring etc so ROI will be a tad longer. :( Still somewhat less work than a lot of systems with complex intakes, long penstocks and very regular maintenance programs. :D Generally the patent holder and others who are building this design are saying, "minimum 0.7m head with 450 litres/sec flow", which would give a quicker ROI.
Presently adjusting, extending details and cleaning up the spreadsheet before posting the improved version.
Rgds, Nat.
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Re: Fish-way using low head hydro turbine
« Reply #10 on: April 04, 2016, 04:46:03 AM »
Find attached version 2 of the spreadsheet. Improved the detail with increments of 50mm in vortex height instead of 100mm.
A little better explanation of some columns and 2 more added, Total efficiency and Reference total efficiency from working installations under similar flow conditions. The reference data is from what could be termed Generation 1 turbines, having less than 80% mechanical efficiency at 100% design flow, which could no doubt be improved to 85%+ with added buoyancy and CFD modelling. Another 5% would have a great effect on the amount of Watts remaining and so increasing the fish way capabilities. For example, a 6.6m diameter tank is capable for slow fish up to 0.702 m^3/s giving 1.1m vortex head, having 85% EffM would enable up to 0.926 m^3/s giving 1.45m vortex head, oh and more power output which would improve the ROI.

Still unhappy about not having an optimum turbine sizing ratio. So now struggling with Euler rotations and may have to learn more about CFD.
Rgds, Nat.
« Last Edit: April 04, 2016, 05:10:22 AM by Natreely »
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Re: Fish-way using low head hydro turbine
« Reply #11 on: April 12, 2016, 01:18:33 PM »
Version 3.
Apologies to all who downloaded previous versions as we just corrected to some degree a mistake in the calculations:
The area of the vortex air core was not taken into account. This correction uses the simple geometry of (1) the lower half of the central vertical column, plus (2) an inverted equilateral cone above, then subtracting this sum from the rotation tank volume Twt. While more complicated calculations could be performed, they are not likely to make much difference to the amount of cubic metres amongst which to disperse the Watts.
You may also notice an unfinished table and a chart of profile curves. This is hopefully leading somewhere...
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #12 on: April 17, 2016, 06:26:34 AM »
Geometry is important to the quantity, quality and velocity of the inlet flow:
9715-0
So, as there is a temptation to have a very narrow inlet with a steeper slope to improve efficiency, increasing velocity and/or Q out of operating parameters...
We needed to add some more columns to the spreadsheet:
R = Hydraulic Radius which is needed in the Mannings formula used for s by Q (slope by flow volume m^3/s) and s by v (slope by velocity).
b = inlet breadth is from cell V3 which is a decimal percentage against cell G3 Fixed do
s by v is red numbers to remind not to take slope from it but use only as a check that the max inlet velocity cell P3 would still be greater than the velocity resulting from what s by Q displays.
The user defined input on row 3 now produce the same table below, so the designer can see how locking in the diameter of the Tank, orifice and turbine has effect on everything else.
Rgds, Nat
PS. The geometry is never a "Golden Spiral" by Phi ratio, but is described as the "involute of a circle," as that is how the water tends to naturally move.
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Re: Fish-way using low head hydro turbine
« Reply #13 on: April 17, 2016, 06:39:06 AM »
We should give credit where credit is due...
The above is resulting from research presented to the IAHR World Congress 2015,
"Experimental Modelling of Flow in an Open Channel Vortex Chamber"
Sean Mulligan, John Casserly & Richard Sherlock
Google the above and you should arrive at the .pdf file from E-proceedings
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #14 on: April 20, 2016, 07:41:24 AM »
Version 5 of the spreadsheet:
Increased accuracy (still rough though) of vMaxt and so likewise RPM due to...
As the geometry is designed for a strong vortex it is assumed that the air core will remain, although decreased, beneath the turbine, so cell N3 is where you define by how much % decrease. This then has effect on the velocity through the orifice as well as turbine RPM.
We will be very busy in the next 4 weeks, so hopefully during that time ,someone will have some more accurate data, formulas, corrections or figures from GWVPPs in operation, which could help improve the spreadsheet. Please feel free to go through the calculations, or put this to Rodrigues and Euler with some Reynolds, Weber and Froude thrown in?
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #15 on: March 03, 2017, 11:06:47 PM »
10283-0
                                  (a) Weak vortex                                                      (b) Strong vortex
Figure 1.1: Schematics of a typical horizontal intake structure with (a) a weak vortex structure during the onset of air entrainment at the critical submergence 𝒉𝒄 and (b) a stable full air core vortex under strong circulation conditions.
Above borrowed from: “Experimental and Numerical Analysis of Three-Dimensional Free-Surface Turbulent Vortex Flows with Strong Circulation”
a dissertation presented by Sean Mulligan in full fulfilment of the requirements for the degree of
Doctor of Philosophy
Submitted to the Institute of Technology, Sligo September, 2015

We need strong rotational flow so that our vertical axis turbine can take energy from the water. Otherwise a weak vortex would have faster vertical (axial) flow with more Watts per cubic metre remaining, consequently making a more difficult or even impossible passage for fish in the upstream direction. With the following optimum provisions in place a strong vortex can be guaranteed:
1.  Exit orifice diameter to tank diameter ratio (see previous posts).
2.  Tank wall and inlet geometry being not circular, but an involute or logarithmic scroll of the orifice circle.
3.  Volume, well controlled between a minimum and maximum design volume.
4.  The Rossby number does seem to have a stabilising effect on the flow and when in larger diameters and closer to either geographical pole, has more effect. Close to the equator or in small diameters there will be no difference. Convergence to a low-pressure centre in the Southern hemisphere happens clockwise, so the geometry shall be designed for clockwise flow and in the Northern hemisphere for an anti-clockwise flow.

We now need a simplified design procedure, which can be refined as more data is proven.
Next up, is a prioritised procedure.
Regards, Nat
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Re: Fish-way using low head hydro turbine
« Reply #16 on: March 19, 2017, 05:29:42 PM »
Sorry, the design procedure is delayed until the next post, because we really should address claims of, “fish friendly.” To be able to compete with accepted vertical slot fish-ways, we need a 100% injury free fish passing rate, so we can call this truly fish friendly. These claims linked below are a very similar design to a fish-friendly GWVPP, so would be easily confused and could give the technology a bad name environmentally.
Hopefully most people are sensible enough that they don’t blindly believe everything that is claimed. These are links to the claims we are referring to, followed by the reasons why they must not be fish-friendly with their existing design.
http://turbulent.be/
The linked page above has a claim of fish friendliness in a blue tab lower on the page.
http://www.ir3s.u-tokyo.ac.jp/3e-nexus/pdf/011817/session3-2_Bajracharya.pdf
The linked page above has a claim of fish friendliness in the design drawings they have borrowed from the Austrian GWVPP design (very different from their design).
10322-0" alt="" class="bbc_img" />
Both Turbulent.be and the Dhakal conical design are intended to operate at higher flow rates than the 480 l/s compared above, so the unfriendliness for fish would be greater. Neither design would be anywhere near possible for fish travelling against the flow (even salmonids), and only fast fish of small size would have good chance of being unharmed going with the flow direction. Likely better than a modern Alden turbine, because there is not as much pressure variation, but worse in the aspect of turbulence and blade strike risk.
https://energy.gov/eere/success-stories/articles/eere-success-story-alden-fish-friendly-turbine-allows-safe-fish
This Alden developed design claims better than 98% success for fish going down through the turbine ONLY WHEN the fish are less than eight inches long (0.2m). Of course, any dam big enough for an Alden turbine would need to have a very expensive and complex fish-way for up-river migrating fish!
Why are we going to so much trouble on this subject now?
This is very important to understand that for safe fish passage in both upstream and downstream directions we must have:

1.   A subcritical flow through the rotation chamber (less turbulence)
2.   A maximum velocity that local fish can swim against successfully
3.   A large enough orifice & big enough blade gap for the largest local fish
4.   Low energy remaining so the local fish like to swim through (W/m3)
5.   The flow rate tightly controlled so design maximums are not exceeded
6.   A slow enough RPM so there is no blade strike risk for fish
7.   A resting pool underneath each rotation chamber

These 7 points will help the design procedure (to be posted soon) make more sense.
Please note: We don’t mean to belittle research work in developing countries where the emphasis is on energy production, that the quality of living may be improved. The chart should demonstrate anyway, that while small efficiency gains may be had with higher RPM, because less gearing is required; designed for electricity is not designed for fish.
One more important issue: Anything less than total transparency in a fish-way/pass, is not good enough. An example to make this clearer, is the Murray River in Australia, where some fish migrate upstream and some downstream. For either direction in the 2000km from the Hume Dam to the sea there are a lot of weirs and locks (about 26 major barriers), so let us now follow a migration path using an arbitrary figure of 5,000 fish at 90% success showing how many remain to face the next barrier: 1/4500 2/4050 3/3645 4/3281 5/2953 6/2658 7/2392 8/2153 9/1938 10/1744 11/1570 12/1413 13/1272 14/1145 15/1031 16/928 17/835 18/752 19/677 20/609 21/548 22/493 23/444 24/400 25/360 26/324 So 6.5% made it through 26 barriers at 90% passing rate, not taking any predation or other causes of mortality into the equation. If the pass rate was only 80% then only 0.3% would arrive or 15 fish out of 5000. Many waterways in Australia have more barriers (often for irrigation) per 100km than the Murray. What makes this situation worse is the fact that European Carp and Red-fin fish don’t need to migrate so their population can increase faster than most of our local endemic fish.
First stage of the design procedure next.
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #17 on: March 22, 2017, 11:38:54 PM »
Fish Way Hydro Design Procedure
1.   Site Survey with 3 measurements: Flow, Head and Fish. Flow measure from on-site measurement as well as historical records within operating flow parameters, namely Compact 400-500 l/s   Medium 255-700 l/s   Maximum 255-958 l/s   Head measure referring to surveyed height difference between tail water and head water (lip of weir full height minus slope of tail race and slope of input race).  Fish measure referring to fish length range targeted for safe passage and swimming capability including burst speed and stamina. Designing for slow fish but extra provision can be incorporated to bring flow velocity <0.5 m/s for species like freshwater crayfish and elvers (juvenile eels), but more detail on that slow traffic path later.
2.   Inlet to control flow volume and velocity tightly:
Using Open Flow Pro, but there are many calculators just as good
The following 3 charts use a Manning’s roughness of 0.013 for concrete. All for a rectangular structure, without adjustment for a slow traffic path

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The reasoning behind the preferred spec (+) in the chart above is, any slower velocity and we reduce the vortex strength too much and any narrower input channel will also decrease the vortex strength, because of the effect on the curve of the tank geometry. Please forget any thoughts of more efficient curves like, full involute scroll, Archimedes scroll, Phi or golden scroll, Bernoulli scroll because although they can be drawn easily enough (extension like Curve Maker to Sketchup), they all make the input critical to supercritical, or in other words too turbulent or having more energy in the water than the fish can swim comfortably. Let us keep the flow tame, ordered, with smooth stream-lines from which it is easier to extract a higher percentage of power.
Next is 3. Rotation Tank Design
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #18 on: March 25, 2017, 12:58:17 AM »
Sorry the following is a correction to the previous post. Note the vortex height at 480 l/s is 0.75m and anyone using the spreadsheet would have picked this up!


If we don't bother to finish the concrete, which is much cheaper. Manning's roughness 0.015 used in the following:


Now we should have a better shape of geometry for a strong and stable vortex.
The rotation tank stage is still around the next corner, just closer now!
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #19 on: March 29, 2017, 10:07:46 PM »
3.   Rotation Tank Geometry – with Sketchup but users of other CAD apps should be able to follow what’s happening.
Now to give an example of drawing the tank. With the constraint that having done steps 1 & 2, lined up the available volume of flow with the available head in the spreadsheet (most recent version 5 posted in reply #14 above), giving us the orifice diameter from the tank diameter. This is the Compact version mentioned in the last post, which we will use in this example. Now a summary of the dimensions we are designing for:
0.75m Height of vortex with turbine (Hvt)
5.88m average diameter of tank
0.88m diameter orifice
inlet having: 0.75m height of water, 0.7m wide, 0.0062 slope, Manning’s 0.015 unfinished concrete, resulting in the velocity 0.91m/s at Q of 480 l/s
Coarse inlet screen of vertical rods having 0.15m spaces
Sliding stop gate on inlet
Fail-safe counter-weighted bottom-hinged weir (flat with river-bed in flood events)
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Drawing in the correct order helps give an accurate sketch. The extra radiating lines in this picture are only lines showing the axis of symmetry, not lines we are using, as we are only drawing a 2-dimensional plan for now.
Draw a circle for the orifice 0.44m radius
Calculating tank inner wall radius plus half of the inlet width 2.94 + 0.35 = 3.29
Draw the inlet width: a straight line from 3.29m towards the centre for 0.7m on the left side of the orifice if you are in the southern hemisphere or on the right if you are in the north, or you can just draw for the opposite hemisphere then flip the whole object along the axis. Optionally you can draw a 2.94m radius circle to compare with the area but this tends to get in the way later.
Using the protractor draw guide lines radiating from the centre in 15 or 7.5 degree increments depending on the accuracy you wish for (24 or 48 pie slices). The first guide line should be on top of your inlet width line. With the protractor tool in Sketchup clicking on the marks inside the protractor gives 15 degrees so it was easier to do this completely, then go back and do it again using the mid-way point between to insert extra guidelines.
Divide the width of the inlet by the number of slices you are using: 0.7 / 48 = 0.01458333
Hit m+ on the calculator to store this in the memory. Working in the direction of the flow, the next guideline after the inlet width line use the tape measure from the centre to mark a guide point at 3.29 – mR (memory recall) = 3.2754 leaving this on the screen, so for the next guide point you can minus the mR again. Keep rounding to 2 decimal places, but leave the accurate number on the calculator so that by the time you get around the tank, you should be exactly at the other end-point of the inlet width line.
Join the guide points together with the line tool.
With the tape measure a guide point 0.05m extending outwards from the inlet width line.
From this new guide-point realign the wall with the draw-line tool, to the second guide-point in the direction of the flow.
Extend this new line straight at least one metre from the original inlet width line.
Draw a parallel line to this at the distance of the inlet width.
Draw the gate section and wall thickness offset from the water’s edge.
Including the stop-gate, a distance of at least 1m, at the prescribed width & slope is needed to control the flow of volume per second, at the prescribed velocity per second. You can now delete guides and unwanted lines from the design.
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #20 on: March 29, 2017, 10:24:10 PM »
With guide-lines, guide-points & unneeded lines deleted, with rough flow lines and colours added the two rotation tanks of Compact Fish-Way Hydro design will look something like this:

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Southern Hemisphere version -–-Compact Fish-Way Hydro--- Northern Hemisphere version

Next Post, we will detail design aspects of the resting pool underneath the turbine & outlet design, before then progressing into turbine design and some interesting new research which has changed the blade shape.
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #21 on: April 15, 2017, 01:23:29 AM »
GWVPP Outlet and Weir with a path for slow fish / crustaceans.
The well oxygenated resting pool beneath the rotation chamber will calm any remaining turbulence before the water re-joins the water-course or enters the next chamber in the series. This resting pool needs to be the same depth as the maximum vortex height designed for above, but doesn’t need to be half the volume of the tank above, so might as well be at a good size for resting the fish as well as from a civil engineering perspective to best support the load of the tank and water above, thus saving concrete. The outlet must be at the designed width and depth for at least one metre to keep the velocity below the maximum specification.
The following plan is to scale for a compact Fish Way Hydro GWVPP showing a 3m wide canal with a lay-flat tilting weir.
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The vortex bypass pipe continuing under the rotation tank from the end of the recessed slow path, could be unnecessary, if a clear corrugated pipe was used extending back into the rotation tank's recessed slow path, for enough distance to control the velocity through it to less than 0.5 m/s. Clear pipe specified because some light filtering through is valuable in attracting slow movers to the passage way. This corrugated clear pipe would ideally be about 0.005% slope to control volume and velocity, with the sizing dependant on what species are targeted. A crawl ramp (if required) can lead up to the bypass outlet into the resting pool, but compensating width and/or depth would be required in the design, so the exiting volume and velocity are unchanged.

Hydro Concrete Structures Engineering Notes
While the above design is with the floor and walls of the rotation tank being 0.15m thick, this will vary less or more depending on the soil, QA of the concrete, the reinforcing design, dynamic loading of extreme floods and the design-years-expected-functionality. With modern best practice, concrete structures can now be designed to last 300 years, with first inspection not required for 80 years. Naturally being in a hydro application, these days we wouldn't use steel reinforcing in the concrete but rather FRP rods combined with Polymer Fibres in the mix, so there are no issues with corrosion.
https://www.vrodaustralia.com.au/designing-with-composite-rebar/
http://danbar.com.au/plastic_injection_products/concrete-reinforcement-fibres
How deep the piles need to go underneath to support all this, would depend on a civil engineers assessment of the situation. Some Vertical Slot Fish Ways in the Hume to Sea project on the Murray River here, had cost blow-outs due to engineers deciding they needed 0.4m thick concrete walls to compensate for unstable soil. Go figure!
Will do a cross-section diagram of that recessed slow-path, which should make it easier to visualise.
Rgds, Nat
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Re: Fish-way using low head hydro turbine
« Reply #22 on: April 22, 2017, 12:24:44 AM »
10410-0
Recessed Slow Path for Fingerlings, Elvers and Crustaceans Bypassing GWVPP Vortex
Having these essential characteristics:
1.   <0.5 m/s velocity
2.   <0.006 m/m sloping 1m length through 0.1 m diameter clear corrugated pipe
3.   <3.7 l/s flow rate for each pipe, add more pipes for larger tanks, or 0.075m diameter pipes for slower flow and more protection for smaller species.
4.   Bypassing the vortex as a continuation of the recessed path in the rotation tank floor, being surrounded either by plantings of endemic aquatic flora or PE/PP bristles to “naturalise” the passage, being preceded by a combination of bristles and flora to lower the velocity as prescribed in literature (see below links).
5.   Enough screening foliage / bristles to give security from predators for slow swimmers. Aquatic foliage planted in the recessed slow path would improve local bio-diversity and encourage more fish traffic. While it is understood that flora do establish in a GWVPP after some months (#3 below), how much better if it started with pre-aged concrete (surface lime pre-leached), and local endemic species which are in short supply planted out in the recessed path?
UK measures for eels / elvers passes:
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/297338/geho0411btqc-e-e.pdf
Which seems to stem from the following research:
http://www.ada.org.uk/downloads/other/downloads_page/Fish%20Pass%20design%20for%20Eel%20and%20Elver%20DJ%20Solomon%20MH%20Beach.pdf
Why should we focus on elvers (juvenile eels) passage for Australia and New Zealand?
Not only because the endemic elvers’ migration is important to the ecology, but because if they can manage to swim against the current, so too can slow swimming fingerlings and fresh water crustaceans (like yabbies). Vertical Slot Fish Ways have too high a velocity and not enough protective cover for fingerlings, elvers and small crustaceans.
Truly Environmentally Friendly
Only by making this facility completely transparent to aquatic life, in other words, no barrier in any way or either direction, can we then claim a total positive effect on the local ecology, including weighing up other benefits like water oxygenation and water homogenization. Due to these measures, local authorities should be more favourable towards this hydro installation being used as a fish-pass / fish-ladder / fish-way / elver-path / yabby-path.
Ref. #3
http://www.zotloeterer.com/welcome/gravitation-water-vortex-power-plants/ecology/
an example of aquatic flora growing on concrete.

Next to look at how recent research will have effect on GWVPP blade design.
Regards, Nat
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Re: Fish-way using low head hydro turbine
« Reply #23 on: April 22, 2017, 12:45:34 AM »
I forgot to mention in the previous post:
Note how the outlet water level is just above the level of the floor of the rotation tank. This means at the lower levels of design flow the slow path for fingerlings, elvers and crustaceans will still work. Please remember though, this design will only work effectively between 400 l/s and 515 l/s flow rate, for example in an irrigation channel that always has this rate or higher with a bypass. Any greater variation in flow rate required, would need to go to the medium size for small rivers, which would give 255 l/s to 700 l/s, giving 1.1m vortex head height using a 6.6m average diameter rotation tank.
Regards, Nat
« Last Edit: April 22, 2017, 03:43:59 AM by Natreely »
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Re: Fish-way using low head hydro turbine
« Reply #24 on: April 28, 2017, 10:55:31 PM »
Apologies again for my being so “almost right” in reply #18, so here are the tables again corrected by spreadsheet and verified with two different formula procedures. This now means that the previously posted drawings of the geometry are now out of proportion by nearly 1m, so will repost when some other factors are decided on. The ios app Open Flow Pro is useful with large amounts of flow but is obviously not accurate enough for our project. Will resubmit the spreadsheet when a few upgrades are finalised, then use cell R3 & V3 in the spreadsheet if experimenting, or:
https://www.eng.auburn.edu/~xzf0001/Handbook/Channels.html
A reliable open channel flow calculator like this is valuable if installing any hydro penstock or irrigation supply channel. A big “oops” if all that concrete is put in so nicely and it doesn’t deliver the required flow, or is so slow it silts up and needs cleaning frequently!





If the size of tank seems very large cost-wise, consider only using concrete for the inlet control race and the rotation tank directly above the rest pool and the outlet. This would halve the volume of concrete needed. Use polymer liner and riprap rocks instead, being much cheaper material and faster to install than concrete, although care needs to be taken that rocks are tightly wedged together if there are any local burrowing creatures like crayfish or platypus. Will give more detail of liner and riprap combinations later.
Hope this makes more sense now. Rgds, Nat
« Last Edit: April 28, 2017, 11:05:58 PM by Natreely »
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Re: Fish-way using low head hydro turbine
« Reply #25 on: April 28, 2017, 11:39:14 PM »
Have a look at the difference between a weak vortex and a strong vortex as posted on 3rd March 2017. From the same research paper quoted there, comes the conclusion of some different flow directions within the vortex, which we illustrate with a simple diagram below.
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Three flow directions are shown. For convenience in this discussion we will name them, VF for the Vertically falling Flow beside the air core, BF for the Base Flow along the base of the rotation tank converging on the orifice centre, and RF for the Rotating Flow which is rotating around the centre axis of the orifice. There is also a minor flow which goes up the walls of the rotation tank, but that will have no effect on blade design so there's no need to discuss that flow.
Please consider how these flow directions have effect on an efficiently designed turbine blade. Helpful to consider the air flow over a wind turbine blade creating lift, keeping mindful that the fluid we are using for that lift is basically non-compressible, much more dense, much slower velocity. Therefore much the same numbers as a glider plane foil, so maybe the same ratio could be used? Instead of lift force against gravity, we will use the lift force against electro-mechanical resistance.
Rgds, Nat
« Last Edit: April 28, 2017, 11:52:37 PM by Natreely »
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Re: Fish-way using low head hydro turbine
« Reply #26 on: May 05, 2017, 04:54:34 PM »
Using Foil Shapes For Hydro Power In GWVPP
From the 3 directions of water flow in the rotation tank (VF BF RF), in each flow we can generate lift on a foil adding momentum in the right direction, if we select an appropriate shaped foil design with a suitable angle of attack.
With KV 1.1692E-6 (Kinematic Viscosity of water at 14 degrees Celsius so use the KV for your local average water temperature), using the Reynolds number calculator on the following page:
http://airfoiltools.com/calculator/reynoldsnumber
Depending on the water temperature and flow rate induced velocity, the Reynolds number will vary between Re 60041 @ 0.3m/s and Re 200137 @ 1m/s with a foil chord of 0.234m. An over-specification flood flow would start filling up the vortex air-core and may increase the VF velocity to 1.35m/s which would be Re 270231, so keep this in mind when looking at charts of foil test results. Otherwise to keep within design spec you may do an overflow bypass channel, or fine control with a sliding gate. Good designing for local conditions should mean there is no need for flow control.

Saving confusion & space we refer to Angle of Attack in Degrees from level flow as Alpha, and the lift Coefficient as Cl.
To save some time researching through hundreds of foil designs, we are only interested in high lift and low Reynolds numbers, which then narrows down to the choice of these:
S1210-il Alpha8 @0.3m/s Cl=1.5 @1m/s Cl=1.9
S1223-il Alpha5 @0.3m/s Cl=1.25 Alpha14 @0.5m/s Cl=1.4 @1m/s Cl=2.25
S1223 with Gurney flap h/c=3.12% Alpha14 @1m/s Cl=2.4
As noted from the research in Low-Speed-Airfoil-Data-V5.pdf the Gurney flap (Gf) hasn’t had much research yet but it does increase lift without a severe drag penalty. For those who are mildly interested but don’t want to investigate, the Gf is a downward protrusion at right angles to the lower surface line at the trailing edge, in this case it would be made of compressible rubber to act as a soft bumper for fish protection.
The S1223 doesn’t perform as well at Reynolds numbers due to less than 0.6m/s water flow, but outperforms everything else at that and above. Don’t know how the S1210 would perform with Gf’s added, it’s a pity that research wasn’t done at the same time.
A practical plan would be, use the S1210 Alpha8 in the slower velocity area for BF and use the S1223 Gf h/c=3.12% Alpha14 for the VF area, which would always be at least 0.6m/s. A twin skin buoyant blade vertically inclined slightly outwards from above the orifice edge can be the solid attachment for the foils. This blade will follow the boundary line between VF and RF water directions, most likely in a 3 blade configuration. At least 2 and maybe 3 foils would connect from the shaft to the buoyant blade, with a tensioning stay.
Use the Text Search box on the following page to find the foil you are looking for:
http://airfoiltools.com/search/index
Some diagrams next, to hopefully make the concept easier to visualise.
Rgds, Nat
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King Solomon