UVM Spout and fittings

[jrgagne99]

Engineer here with a background in fluid dynamics. I had the same thought... I would be surprised if Reynolds number there is greater than 2000, let alone if the sap is even flowing at full-pipe? I'm not disputing the experimental results, but I wonder if the turbulence/friction hypothesis is correct. Did the internal flow radius alone produce increased sap yields, or was it the barbs at the tip of the tap as well? Reducing turbulence and friction has a nice marketing ring to it, I'm just not sure that's the actual mechanism.

One way to test it might be to diagonally insert a thin metal tube into the tap-hole from above the fitting and measure the delta-P across the Arc-Flow fitting during sap-flow event. Compare this to a similar measurement on a standard right-angle tap. You would probably want to measure the sap flow during these tests as well to get dP-vs-Q for each.

Edit: I just saw the youtube videos of the 5 different configurations, and the qualitative differences are clear. I just wonder how much those differences affect the vacuum level in the tap-hole. Also if the flow rates shown are prototypical for sap flow.

[DrTimPerkins]

You use the word turbulence multiple times (I bolded). With my journal reviewer hat on, are you sure that turbulence is the correct word. I am not sure what the Reynolds number is for sap coming out of tree but I would be surprised if it was fully developed turbulent flow. Laminar vs turbulent is important for drag, any build up on the walls, etc. If you have published work on this, please point to the paper. I could be total off base also so please correct me if I am wrong.

I guess I was unaware that my post on MapleTrader was being peer-reviewed? Turbulence would seem to me to be the proper term...would you suggest another?

There were no papers published prior to the announcement at the NAMSC meeting in Wisconsin in October, although we've talked about (and lab and field tested as appropriate) and published several different concepts on sap flow/yield in tubing systems over the past 15 yrs (just not these particular things). In this case publishing would have been a bad idea given that these are (potentially) patentable. Now that those applications have been filed, we are starting to write about them.

The information we have on flow dynamics in trees and in lateral lines under vacuum conditions is not well known or available in the peer-review or grey literature. Typically we keep certain bits of information like this close to the vest until we have a really good understanding and have repeated measurements over several years and conditions. Several reasons for that approach that I won't go into unless folks are interested.

[DrTimPerkins]

Engineer here with a background in fluid dynamics. ...

Admittedly I am not an engineer with a background in fluid dynamics. Sap flow in a 5/16" tubing system under vacuum mixed with gases (leaks and tree-derived) is quite complex and highly dynamic. I have spend a good part of the past 20 yrs observing and measuring sap flow from trees and in tubing systems. I can't say for sure whether the turbulence/friction hypothesis is correct, but am happy to have the conversation. Doing it within this forum is rather kludgey however.

I think there is some confusion here regarding two of these things. The barb-spout is one, the arc-flow feature is another. There was no difference in the internal diameter (what you refer to as flow radius) between the control spout and the barb-spout. Testing of the barb-spout was done with straight-through spouts (both control and barb-spout). The only difference was the length of the spout barrel (reduced in the barb-spout) and the barbs themselves. Otherwise, these were as identical as possible and machined from the same polycarbonate stock. We tried a number of variants of different spout features for a few years before settling on the short barrel/barb features. Then we tested that for the past 3 yrs with good results.

The arc-flow feature is more of a theoretical concept based upon what we know about sap flow/air movement in these systems, modeling studies, and some lab-based simulations. We have not been able to do field trials as yet because nobody makes anything like this and the design isn't amenable to small-scale production (machining fittings). Rather, the parts have to be injection-molded (not cheap, not quick, not easy). We are in the process of getting that done now.

Bottom line is:
1. Yes, I understand that people have questions and are eager to hear answers.
2. I try to answer those questions during presentations I started in WI and will continue this spring.
3. Unfortunately, this forum is not really conducive to going through the entire thing well.
4. Publication of papers on this is in progress.
5. Large-scale field trials are (hopefully) going to happen in spring 2023.

So best I can say is to stay tuned.

[ebliese]

Am I correct in presuming the large scale field trials will include people on buckets? It was very interesting to read of the 10-23% increase in sap yield but wondered if that was primarily on vacuum or would apply to buckets.

[DrTimPerkins]

Am I correct in presuming the large scale field trials will include people on buckets?

We will be testing on vacuum only in 2023. Once we get that nailed down, we (or someone) will likely test it on gravity.

[jrgagne99]

Agree that the forum is a klugey vehicle for technical discussion. I for one will definitely stay tuned for continued results presentation, good, bad or otherwise! Sounds like the barbs it could be nearly as big as CVs were a decade or more ago!

[Maples Maple]

I am looking forward to the results also. Video 4 does look like it might be turbulent.
Adding gasses and vacuum definitely complicates things. I am an engineer but not a turbulent fluids expert.

I understand keeping things initially as a trade secret or patent. I think that it is an interesting engineering problem and was (am) hoping someone was (is) diving in deeper.

Good luck!

[220 maple]

Dr. Tim
Just talked with Dr. Rechlin, glad to hear that you got some sent down are way, they need tested in the Walnut trees that are being tapped, Dr. Rechlin and my friend that has the 1000 walnut tap operation keep real good records! You will get valuable data from them!
Mark 220 Maple

[DrTimPerkins]

Just talked with Dr. Rechlin, glad to hear that you got some sent down are way, they need tested in the Walnut trees that are being tapped, Dr. Rechlin and my friend that has the 1000 walnut tap operation keep real good records! You will get valuable data from them!
Mark 220 Maple

They're being tested in Ohio, WV, NY, VT, and Qbc this spring. Just sent out to all the test sites yesterday. Polycarbonate version of Barb-Spout and regular spout (control) are being tested, but they can be made in nylon as well.

polyspouts.jpg spouts-arc-tee.jpg

[DrTimPerkins]

One way to test it might be to diagonally insert a thin metal tube into the tap-hole from above the fitting and measure the delta-P across the Arc-Flow fitting during sap-flow event. Compare this to a similar measurement on a standard right-angle tap. You would probably want to measure the sap flow during these tests as well to get dP-vs-Q for each.

Yes, that would work well in a controlled situation where flows were relatively constant. Doing that under varying sap flow conditions in the field is considerably more problematic, especially since the influence of any one spout or fitting is likely to be small. That approach would also require repeated measurements under a variety of different sap flow conditions and then extrapolating that over a season.

Alternatively, what we ARE planning to do is to measure and record the vacuum level at both the mainline entrance and at the end of the same lateral line for lines that incorporate the Arc-Tees and Barb-Spouts for other lines without Arc-fittings. So we're looking at the differential vacuum levels across the lateral line. Since there will be several fittings in the line, and the effect of each fitting is additive, we should (theoretically) get a higher signal. We will do multiple, season-long measurements and recordings of these data on several lines of each type (standard fittings and arc-flow fittings), and also measure sap yields from (multiple) systems incorporating each of these fitting types. There will be a total of 4 lateral lines of each type (standard vs arc-tee) with sensors at the start and end of each lateral line that are measured over the season to determine if there are any vacuum differences and under what flow conditions. We will also be measuring sap yield from 6 mainlines of each type (standard vs arc-tee) measured over the season. All these 12 mainlines are located in the same area with the same population of trees. Mainlines were randomly assigned to the treatments (Arc-Spouts/Arc-Tees) or standard (90 deg spouts and 90 deg Tees).

Each of the lateral lines will have 3 taps/lateral to keep that constant. Lateral line lengths will be similar for each system. All 12 mainlines will be operating off the same vacuum pump, but each mainline goes to a different custom mini-releaser equipped with a counter. These are calibrated so we know precisely how much sap if collected for each dump.

In short...this type of work isn't as easy as doing one measurement across a fitting once or twice. We're looking at vacuum and sap yield across an entire section of the sugarbush over an entire season. Not cheap, not easy...but the results are more meaningful and more representative of what maple producers are interested in.

That is....if we can get the systems set up in time. We just got the fittings a couple of days ago.