nixit Posted February 26, 2011 Report Share Posted February 26, 2011 Hi. I am a noob. I love Mr Whisperers stuff. I watch his podcasts religiously and repeatedly. As an Aerospace Engineer, I thought it'd be fun to over think things. So, I'm seeking comments on this: I chose the wood craft trash can design, as it was the simplest by far. http://www.woodcraft.com/Articles/Articles.aspx?ArticleId=408 (used with out permission) So far, I've spent 29.99 on a 32 Gallon Trash Can. I plan to mount it above the blower motor on a shelf. That way, I'm using as little footprint as possible in my little two car garage (that still holds two cars). For my cubic feet per minute (CF/M) variable, I used 500CF/M based on Bill Pentz data. I chose 500CF/M, because that's worst case (hopefully). (used with out permission) http://billpentz.com/woodworking/cyclone/DCBasics.cfm So I entered in a few models into Catia and generated some fluid dynamics to determine the best port setup... First up, is based completely on the WoodCraft design. I like how it tumbles out and water falls all the way down the walls, before being sucked into the vacuum. Second on deck, is based on the woodcraft design, but I added a 90* elbow. Tons of swirl. The longer the dust/dirt/chafe is in the can, the better the chance I have that it will drop out of the airflow and settle in the bottom. What I do notice about this one that I do not like is the teal blue lines that cross over and around the top... Straight from the inlet, right into the outlet. Not idea... BUT, it sure has lots of cyclonic action going on otherwise. Maybe a diverter can assist me. More modeling and analysis may be needed. So what would happen if I have one port pointed one way, and just a straight pipe about 270 degrees out around the can... I'm not sure what to thing of this one. Lots of tumble. And Generally just a mess. Is this a GOOD thing? I couldn't find many short/direct runs when analyzing the results in 3D. It tumbles out of the inlet port (dirty air enters the straight pipe) hits the bottom, and then gets sucked up through the 90. What I don't like is that there is no cyclonic action going on. Now THIS is a cyclone! Wow. Tons and TONS of swirl. But does this mean it will perform better then the second one? I don't know, but I like this one. I may do some more research and move one of the pipes 45 degrees closer... more research. I spent one evening of my time (about 3 hours), making all the models. Then it took me another evening to perform the Computational Fluid Dynamics on all four models, and generate the pictures. (4 Hours). As always, comments are always welcome here. Total Cost to date: $29.oo Trash Can plus $129.oo for the Dust Collector (Harbor Freight Model, on Sale + Coupon) (copied and pasted from my private blog) ((SORRY for the MASSIVE size pictures... the blog does thumbnails then you click to make em MASSIVE)). Quote Link to comment Share on other sites More sharing options...
Vic Posted February 26, 2011 Report Share Posted February 26, 2011 VERY cool! Thanks for taking the time to do this. I have a cyclone, but love the science behind your prsentation. Quote Link to comment Share on other sites More sharing options...
rmac Posted February 26, 2011 Report Share Posted February 26, 2011 Cool stuff! Are you are aware of Phil Thien's work? It would be interesting to see how a model of one of his separators compares with the ones you have done already. -- Russ Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted February 26, 2011 Report Share Posted February 26, 2011 I was thinking about this sort of model with the Thien. If I understand, in the Thien separator the air just travels in the upper section and never gets down into the bucket (where it can pick up dust). The dust bumps up against the walls of the upper section, slows down, and drops out of suspension. Then the dust falls down into the bottom section. So, the airflow model should just show the air going around in the top. Quote Link to comment Share on other sites More sharing options...
nixit Posted February 27, 2011 Author Report Share Posted February 27, 2011 Thiens. Not exactly the same, but close enough. Considering it's just a board with some long all-thread and fender washers, it doesn't complicate things too much. Annnnndddd.... Discuss. Quote Link to comment Share on other sites More sharing options...
rmac Posted February 27, 2011 Report Share Posted February 27, 2011 Am I correct in guessing that the colors in your pictures indicate the air velocity? And that green is faster than teal is faster than blue? -- Russ Quote Link to comment Share on other sites More sharing options...
Sac Posted February 27, 2011 Report Share Posted February 27, 2011 Wow.. do you like to do this, or do you have too much time on your hands? This is really great stuff. I dont suppose you know how to measure air flow in a system do you? I am really curious how much air I am moving through mine.. Quote Link to comment Share on other sites More sharing options...
jlawyer Posted February 28, 2011 Report Share Posted February 28, 2011 I've run similar simulations in CFDesign, but what I've never managed to figure out how to simulate in computation flow sims is the particle presence and velocity in the air. Does Catia use the same flow sim as Solidworks? Quote Link to comment Share on other sites More sharing options...
joebecquets Posted February 28, 2011 Report Share Posted February 28, 2011 Many thanks Nixit for this fascinating piece of information. I have a question. I don't remember having seen the cyclonic lid attached to any other dust collection machine than a ShopVac (or its equivalent). Is it possible to attach it to a more significant dust collector without losing too much CFM? Many thanks! Quote Link to comment Share on other sites More sharing options...
ChetlovesMer Posted February 28, 2011 Report Share Posted February 28, 2011 Many thanks Nixit for this fascinating piece of information. I have a question. I don't remember having seen the cyclonic lid attached to any other dust collection machine than a ShopVac (or its equivalent). Is it possible to attach it to a more significant dust collector without losing too much CFM? Many thanks! I've seen that done many times. I don't have a picture for you, but there's no reason why you can't do it. Quote Link to comment Share on other sites More sharing options...
ChetlovesMer Posted February 28, 2011 Report Share Posted February 28, 2011 Wow, that's cool information. It's good to have you in the forum, Nixit. Thanks for posting. Quote Link to comment Share on other sites More sharing options...
nixit Posted February 28, 2011 Author Report Share Posted February 28, 2011 Am I correct in guessing that the colors in your pictures indicate the air velocity? And that green is faster than teal is faster than blue? rmac, Correct, I figured Velocity was a greater interest to me then pressure. I did measure and analyze pressure too, however there wasn't anything remarkable that it revealed. Wow.. do you like to do this, or do you have too much time on your hands? This is really great stuff. I dont suppose you know how to measure air flow in a system do you? I am really curious how much air I am moving through mine.. Sac, Yes, I enjoy CFD a lot. Each calculation took about 3 minutes to run. The hardest part of the entire project was creating the picture collages. No sarcasm. Modeling the trash cans and elbows/union/etc was only mildly time consuming. I've run similar simulations in CFDesign, but what I've never managed to figure out how to simulate in jlawyer, computation flow sims is the particle presence and velocity in the air. If I were to use CD-Adapcos software, I'd be able to run full particle analysis. It takes specially written algorithms, however, it's available on their end-user forums. Modifying the code and running the analysis maybe be more time consuming than it's worth. I have a question. I don't remember having seen the cyclonic lid attached to any other dust collection machine than a ShopVac (or its equivalent). Is it possible to attach it to a more significant dust collector without losing too much CFM? PaulR I don't know. I've seen so many variations of dust seperationc/colleciton in my research, that very few are attached to a shop vac (except the Onieda one). I figured the trash can is sized correctly for the single Harbor Freight 2hp dust collector. I know I will be taking a 4" air feed and neck it down to about 3.5" (PVC Piping), but I *think* i'm willing to take that hit. If your unit is really as big as what you linked to (3hp vs 2hp), then I'd just get a larger trash can. The 44 Gallon one was $39.99, but far too large for my intentions. It's good to have you in the forum, Nixit. Chet, Thanks. I figured I'd post my 'exclusive' cr4p here. I respect the Whisperer Fella's stuff a lot, and thought I'd give back a little, and maybe learn something from peoples comments/criticisms of this post. I think so far, from what I've seen, doing a variation on the Thiel is in my best interest. I think what I want to do next is just have a simple round disk hanging down, with about a 2"-3" gap between the trash can wall and the disk all the way around. I'm going to do some more analysis along those lines in the coming weeks, but one of the keys will be 'simplicity'. I don't want to go nuts with fixed diverters, motorized gates and flashing LEDs. Quote Link to comment Share on other sites More sharing options...
rmac Posted February 28, 2011 Report Share Posted February 28, 2011 I think so far, from what I've seen, doing a variation on the Thien is in my best interest. I think what I want to do next is just have a simple round disk hanging down, with about a 2"-3" gap between the trash can wall and the disk all the way around. I'm going to do some more analysis along those lines in the coming weeks, but one of the keys will be 'simplicity'. I don't want to go nuts with fixed diverters, motorized gates and flashing LEDs. Nixit, Thanks for the update! I have a Thein setup in a 30-gallon trash can with a shop vac for suction, and it works far better than I ever imagined it would. Virtually nothing makes it into the shop vac. I made the disk itself exactly according to Phil's instructions, with a 1-1/8" wide gap that extends 240 degrees around the perimeter. Instead of hanging the disk from the lid, I mounted it directly to the walls of the can. Somehow that just seemed simpler to me. The other thing I did differently was to bring the inlet in tangentially through the side of the can, rather than through an elbow hanging down from the lid. I figured that one less elbow would be good no matter what, and that it would be good remove that obstruction (the elbow) from the cavity above the disk. I also had the vague notion that the airstream would be "better behaved" (whatever that means) on entry to the can if it hadn't just gone through an elbow. Anyway, it will be interesting to see the results with your proposed disk configuration. If you're so inclined, I would also be interested to see how the tangential inlet compares with the elbow. -- Russ Quote Link to comment Share on other sites More sharing options...
jHop Posted March 1, 2011 Report Share Posted March 1, 2011 [...] but one of the keys will be 'simplicity'. I don't want to go nuts with fixed diverters, motorized gates and flashing LEDs. But LEDs make everything cooler! ( ) Personally, I'd be interested in a rough approximation of what moving the inlet line to the side would do to these fluid dynamic projections... I'm in the process of relocating the dust collection units now. (the current one is clogged, which I did not discover until last month. Right after I discovered the furnace was taking over the dust filtration duties...) Quick question: has anybody seen the basic collector plan out on the web? It's basically a box, about three feet wide, with two angled portions for intake and outtake (approx 25 degree), with a baffle in the middle so the air flow has to drop below it (thereby releasing the dust, in theory) before going back out the next line. I'm thinking of this for a downdraft table, instead of trying to add 30 feet of ducting to the other side of the room for just one function. Quote Link to comment Share on other sites More sharing options...
Beechwood Chip Posted March 1, 2011 Report Share Posted March 1, 2011 I've seen that plan, but I forget where. I think I'd add a furnace filter, and just use the baffle to extend the life of the filter. Quote Link to comment Share on other sites More sharing options...
DoctorDan Posted March 6, 2011 Report Share Posted March 6, 2011 Very impressive models. I haven't seen that elsewhere. Good work. Quote Link to comment Share on other sites More sharing options...
nixit Posted March 6, 2011 Author Report Share Posted March 6, 2011 All, I've been pretty busy with work, but I plan to revisit most of the models with a side entry instead of the 90* fitting. Stay tuned. Quote Link to comment Share on other sites More sharing options...
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