I learned with my solar thermal experiments that static pressure is as important as airflow when it comes to accomplishing work efficiently. Few channels do experimentation like this, not as many clicks as crushing things in a press or blowing it up I guess, but I appreciate the data. Very useful. Thanks!
Never claimed to be smart bud. Just pointing out that though most of the gen public would find this boring, I and likely most of Matthias's subs appreciate the extra effort to show exactly why one configuration is better than the other. Everyone owns a channel for different reasons: some informative, some entertainment, some for clicks and $, some just to goof around. I think (almost) everyone can be as smart as they choose - most people seem to be pretty clever when they want to be...
@@satibel Best cooling came from a Siemens i used to own. All the fans were oriented towards high static pressure. Temps never rose above 50C in any of the stages of use, regardless of how much number crunching i was giving it, but then again Siemens used to make some bitching portable server cases, with airflow in mind (haven't used on in many years, having gone to liquid cooling).
If anyone ever wanted a true definition of "Research and Development, they would only need to see this current video of yours. I for one find your videos extremely fascinating, and I have learned a lot. Thanks Matthias!
I'm just starting to design my new shop and my dust extraction system is a top priority. This test will actually help me make some piping and hose decisions. Thanks.
Mathias, thank you for doing my job for me! I was about to conduct a very similar test but this confirms my suspensions and will help my project get along faster. Thank you for your channel!
FANtastic. Oops, did I just write that? Your work with these systems is amazing, and I am sure we are all learning something new with each experiment you perform. I am so gonna try making one of these in the very near future. Keep up the good work.
perhaps add smooth hose versus flexible/concertina hose to your comparison chart... tho that then brings in a whole new discussion about surface/laminar flow :)
These hoses are actually quite smooth inside. Besides, wobbly surface could have better performance, especially for curved paths. Watch Mythbusters video about golf ball aerodynamics, they've explained it quite throughly.
This was a really informative video Matthias. Thanks for making it and other ones like these! It doesn't seem to matter what topic you chose (wood, shop, home, camp, random) I always enjoy your style and learn something. Please keep making them!
I have no dust collector because I ussually do woodworking outdoor. I have no skills on building this machines. I do not have those measurement instruments... but, I'm engineer, I do woodworking... and enjoy like a kid with this kind of videos. Thanks!
Thanks very much for this Matthias. I have worked on industrial dust collection/ air movement systems my whole career and i have seldom seen these sometimes counter intuitive engineering principles explained so clearly. Well done, you have a way with words (and video). Forget the pedantic types, I suspect most of your viewers, like myself, don't have any time for them either... aren't they first cousins to trolls on the evolutionary tree?
I love your vids, Matthias...mainly because you make me think about things in my workshop that I never knew I had to think about. Thanks for keeping me on my toes!
Since you keep mentioning noise I'd love to see you do an experiment with asymmetrically-spaced blades and an explanation of the effect on noise. (Awaiting classic Matthias response "Nah, too much trouble, just wear ear protection") Favorite channel on youtube - thanks for the great videos!
awe You forgot the statistics in the science department! You need a repetition of 4-5 (maybe 20) depending on the Power you want/reduction of non-systematic errors/outliers and to achieve some sort of normal distribution of the recordings. Then you may call this an experimental Science video, not just a Screwing Around demonstration video. ((but this calls for building a zillion blower houses -- I didn't count the configurations/designs/ie treatments he made so I'm guesstimating -- but then, Matthias isn't the pedantic type, unlike me))
Have you had a look at using small splitter vanes between the leading edges of the blades? It looks like a very easy thing to add in and apparently helps with static pressure of backward bladed fans. (see "Impeller Treatment for a Centrifugal Fan using Splitter Vanes - A CFD approach" for more info)
Matthius, Again a BIG THANK YOU. The ClearVue Cyclone uses a 16 inch impeller vs. the aveage 11 to 12 something impeller. From what I've read The CFM and I'm guessing the static pressure? is increased by impeller size. You changed the restriction of air flow in the impeller which increased or decreased noise and cfm ( Imperical units LOL!) The only thing you left out of your experiment , I believe, is reducing the space from the impeller to the shrowd/housing? I have used my own tests with an anemometer and confirmed loosing more than half the cfm that comes out of my Thein separator, which also reduces the cfm. I knew that from just listening and watching and checking suction. My DC is an older delta 1.5 hp. Checking it out I found the impeller to be fairly straight like the old washing machine agitators The spiral experiment you did confirmed my thoughts. I'm going to re-watch your video as it helps make Bill Pentz's information more concrete.. I'd already figured I have to increase the size of my main feed and decrease the resistance of air flow by eliminating the crrigated smaller 4 " hose . Size of my motor limiting pipe size to 6 inches. Another question or thought that came up as I examined the shroud or housing is the 6 inch connector reduces down to around 5 and a half inches. Is the venturi principle in effect and if so how?
From what I've read so far: flexible tubing with its ridges introduces a lot of pressure drop especially in any bends. Ironically in HVAC systems all the bends ought to be done with rigid smooth walled piping if possible but you can use flexible tubing for the straight runs (and nothing else) if you want due to its ease of transport and installation!
Flex will always bring more disturbance than smooth wall. In ducting its key to run your main through the house and then use as little flex as possible to connect vents in odd areas. We do see a lot of flexi duct being used now but you as the consumer have a voice. It has to do with how much you are willing to pay and proper planning for a project. Shortcuts always cost you more money in the long run!
nice, really enjoyed the series. Was going to do something similar to continue building the dust collector, but don't have enough time. Thanks for doing the experiment for me :)
Very useful information and great detail! Thanks for taking the time to share this. I am making a localized fume fan for welding and had questions that your video answered quite well! Thank You!
I have couple of ideas. Test some variables: Distance from lid to impeller. Size of inlet of impeller. Impeller with and without top ring. Fix description: eirflow->airflow Moe->More
To find the most efficient shape for a fan, just look at fans? The blades are in a spiral but they're also curved diagonally. Airflow fans use +-12 smaller blades with gaps between the blades so air can more freely flow through it. Air pressure fans use +-6 bigger blades and are spaced closer to each other so the air builds more pressure before it is released. The designs aiming for a mixture of both use +-6 bigger blades with extra gaps between.
From what I've observed, forwards facing curves are more efficient at producing high outlet pressure while backwards facing curves are more efficient at producing high inlet vacuum levels. So, for a dust collector, backwards facing is better.
I was planning to make an heat exchanger, and doing some guestimate, I figured that the pressure was an huge factor, and caused an huge flow loss. I'm still looking for some inexpensive blowers for it, and I can't find anything with enought CFM and pressure. I might be forced to actually stack two, one on the intake and one on the outtake, just to get enought pressure... A royal PITA for sure.
A smooth flange on the inlet (or outlet) of pipes also reduces the airflow resistance quiet a bit. Especially like your cyclone inlet. It also reduces noise because there is less turbulence. edit: What's even a better idea, is using a tapered section from the full width of the cyclone to the width of the pipe.
Oh, and it's pretty much well known that these flexible pipes/hoses have a very high flow resistance because of their shape (curved) and the fact that they have such thin walls (move/vibrate easily). They need to be short as possible and connected to something like a smooth PVC pipe. (Are there any flexible pipes with smooth inside walls?)
the difference in the sharp edge in the spiral housing comes with pressure build up at the blowing side, as does most of the benefit of the housing itself. that being said, since you have made a rather robust blower, wouldn't it be better to blow trough the cyclone instead of sucking trough it? this would mean getting dust in the blower but it looks like it can handle that, plus the dust wouldn't pile up in the high flow areas. building pressure is easier than removing it, since the air needs something to push against to impart energy, building 0,3bar abs requires about as much energy as building removing another 0,1bar from that, given a closed volume. then again it might make 0 difference given the large restriction of the hose and this device working more on mass flow than pressure (though as you pointed out, pressure is still important)
you could try fewer or less fins on the fan changing the shape of the fins adding a dome or cone in the center trying sharp or dull edges, since most fans have a thick body but sharp fin edges. polished or rough / soft surface on the fins (a pc fan manufacturer used some sort of fleece on the fins to reduce noise.)
You should try to get your hands on a blower for a small bounce house. I have one left over for my sons bounce house from when he was a little boy... thinking about making a dust collector for my sanders with it.
Love the new data. I wish there was RPM data in this test too, but having the anemometer close to the inlet I agree is a much better spot. Maybe the next time you can pinch down the diffusing section axially, and have it diffusing to a bigger diameter before entering the volute.
great video ,,,, explains a lot , the length of flex hose will probably effect it as well ,,,, seeing that the hose had the biggest resistance ,,,,, would be nice to see the resistance from 90 deg elbows and 2- 45 deg and flex pipe like for a full shop dust collection set up
With a centrifugal compressor it probably is indeed most efficient to collect the air equally from every side of the impeller. This arrangement would be kind of like in early British and American jet engines which used centrifugal compressors - the air was pushed into ducts laid out around the compressor, and into the combustion chambers, and then through the axial turbine that powers the compressor. But, it would make for a rather complicated design with a lot of ducting, and the ducting itself could actually end up hinder the airflow more. Most centrifugal compressors used in turbochargers have the spiral or snail shell-like housing, so probably the simplicity from having one outlet outweighs the advantages of multiple outlets set equally around the impeller.
I was going to suggest that maybe you try curving the inner wall of your spiral but that would just create more surface area and likely increase static pressure. After seeing you put stuff into your cyclone and air flow increasing, I now think maybe you should try channeling your spiral chamber by puting a divider through all or part of your spiral chamber to see if that increases air flow.
Wonder if a larger diameter cyclone can would greatly benefit the system? I'm now going to look at changing my hose system to use a few short pieces of flex interspersed with solid sections of pipe. My shop layout can support this, YMMV.
Restricting the size of the hose would also improve air pressure, maybe you could experiment with that, I thought also something similar to a beater bar to break up the path of sawdust/chips like an upright vacuum uses would help with air flow without increasing motor size and/or suction either, also would agitating the air flow by interrupting suction possibly by using an elliptical blower or one way valve make a difference? but as a last resort wouldn't just increasing the brute force of the hp/amps of the motor help with atmospheric pressure?
You should look at air handler blowers. They use squirrel cages with the curves in the direction of rotation. Opposite of a water pump. It comes down to if you want high CFM or high Static
I made some experiments with cyclones and airflows myself and came to an interesting conclusion: The diameter of the cyclone is surprisingly irrelevant. I thought a smaller cyclone would make for faster rotation and thus for more resistance but I tested three variants from 400mm to 590mm diameter and they were pretty much equal. Also there wasn't much difference in their ability to catch the dust. So I went ahead and ordered one of the totally overpriced dust deputies (125mm inlet version) and was really surprised: With that cyclone the air flow almost doubled. I don't know why the air in there rotates so much more "efficient" but it has a lot less resistance and I don't see a difference in it's performance yet. Still most of the dust goes into the bin. So it seems to be a good product, but the price... nah. But if someone here reads this and is thinking whether the effort of building one on your own is worth it: Yes, it is. Marius Hornberger has some videos about it. Hope this helps. Took me several days to build all those cyclones. For separation it doesn't matter what design you chose, but for airflow: Use the cone shape. Wish I could explain why.
Rainer Zufall, Marius, and Matthias have explained this in older videos to some degree. Also Phill Thien's website explains why the baffle has less air flow, but keeps the dust rising out of the collection bin when it gets almost full. Basically, the baffle creates a positive pressure lobe at the center, causing a lot of resistance. Well, that's the best way I can explain it.
I only know all the videos from the first two :) At least I cannot recall any comparison but they have a lot of videos and I have a bad memory so I may be missing something. But today I want to add: Just in case someone wonders how good the dust deputy is at separating fine dust from 120 grit sanding: It is pretty much 60-70%, which I think is really good. Did a lot of sanding today with my drumsander. 30% goes to the filter but considering we are talking about really fine stuff I think that is good performance. I wonder if you can get more performance with another setup. With the good airflow a two stage cyclone would be possible but will it really help... hmmmm.
I realize I am late to commenting on this video but was wondering if the shape of the cyclone matters? A lot of the commercially available cyclones are cone shaped with the exhaust at the top, where as yours is just a cylinder? Would the cone shape help push the air up towards the top and therefor decrease restrictions?
have you tried making a stater? also, this should work differently when on the exhaust port vs on the intake for a pressure reading. considering your readings i would make a wheel that more closely matches your system, thinner and larger diameter. should give the benefit of having more differential pressure and less noise. but you wont have the mass flow when you disconnect the hose ect.
Have you ever compared the static pressure at the inlet to the pressure you could obtain from a venturi? I've always wanted to experiment with making a venturi-style dust collector, that way the blower doesn't suck up any dust and debris, it simply blows the air across a venturi tube which does the real suction.
Another awesome video from Matthias! The take away for me, since I want to build a leaf vac attached to my ride on mower, is just build it. for that purpose it seems like all you care about is flow and not pressure. the push lawn mower that I'll sacrifice will have enough flow for even wet leaves since I'll have the ride on mower helping. no need for special housing, just mount it on the trailer and cover with a bed sheet(like the video Matthias already made but without the housing). any thoughts?
I'm sure it's been said but I would love to see a comparison of differing lengths of solid pipe and flex pipe with the same length run. I'll be honest most of this video was over my head but I'm sure once I'm working on a comparable project I can refer back to this and get more necessary information.
Matthias, If placing obstructions in the cyclone path increases airflow, then would you do a video on different shapes mounted in the cyclone bay in an attempt to optimize pressure. Please Possibly a cone shape or perhaps a polygon. I'm very interested in this because my shop is a literal garden shed measuring 10' X 14' and I have absolutely no spare room, so I need my Home Depot Bucket head vacuum to work better than it does currently.
Thank you for the great demo. However I wished you also showed the change in static pressure at the outlet. For all the applications when you need to pressurise a space. Can you please show that in a future video. Only you can do it 😊
Hello Matthias, First of all, I want to thank you for your extensive and educational videos! They are truly amazing! Very useful, especially now that I'm planning to make my own fan. Secondly, I have a question: Have you ever considered making a double suction blower? And if not, why not? Greetings from Holland!
Try using a smooth bore inlet pipe so there is no turbulence created by the corrugation in the pipe. also aircraft reduce friction/turbulence by the outside being polished so coating the inside of the components with a low drag coating may help?
I had a similar issue trying to lengthen a AC venting hose in my bedroom. It came with like a 10ft hose, and I tried to add another 8 feet or so, and it just couldnt evac the hot exhaust worth jack all. Go back to the factory length and it was cold, add my extra 8ft, the room barely got cool.
if you wanted a LOT of static pressure it seems you would need a really big blower. but noise and power consumption would obviously increase, and its less efficient for the same motor size. Im wondering if there is a series or parallel configuration where you could run two smaller blowers, and generate the same static pressure of a single large blower. But both motors draw less watts combined than a single motor.
okay here's my scenario it doesn't really involve joyner's planers or table saws or any of the wood dust collection that you're dealing with my situation is dealing specifically with dust collection from a four and a half inch Grindr using 36 Grit sandpaper and it produces an enormous amount of dust so much it covers everything in the shop and I guess I was just trying to find something that had an enormous amount of suction that could deal with the situation.
So the conclusion is, looking from above; a larger inlet(?) with a smaller outlet but A third/half the radius from the west side compared to the south east to let the air spin to aid the Propeller and reduce wattage. Yet build up a better static pressure. This means, you compress the air at the inlet and therefore create a better pressure of air which increases static pressure, no? Bit like taking a hose of water and squeezing the entrance, which doesn't make any difference in how much water leaves the hose but it increases the pressure so you can water a larger distance.
I built a dust colle Collector from a Blower out of a dryer and it didn't have alot of pressure because the blades are backward curved but if I reverse it then I also have to reverse the housing but that's easy to do.
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I learned with my solar thermal experiments that static pressure is as important as airflow when it comes to accomplishing work efficiently. Few channels do experimentation like this, not as many clicks as crushing things in a press or blowing it up I guess, but I appreciate the data. Very useful. Thanks!
Static (back) pressure is one of the most valuable data points even for PC coolers but is the most overlooked as well.
Most channels can't analyze data, and don't want anything but money.
Never claimed to be smart bud. Just pointing out that though most of the gen public would find this boring, I and likely most of Matthias's subs appreciate the extra effort to show exactly why one configuration is better than the other. Everyone owns a channel for different reasons: some informative, some entertainment, some for clicks and $, some just to goof around. I think (almost) everyone can be as smart as they choose - most people seem to be pretty clever when they want to be...
high cfm fans are good for cases, high static pressure fans are good for heatsinks.
@@satibel Best cooling came from a Siemens i used to own. All the fans were oriented towards high static pressure. Temps never rose above 50C in any of the stages of use, regardless of how much number crunching i was giving it, but then again Siemens used to make some bitching portable server cases, with airflow in mind (haven't used on in many years, having gone to liquid cooling).
I love these kinds of videos. Such a great way to get intuition - just do a bunch of tests.
"To the pedantic types"! 😁 Thanks for sharing this experiments, Matthias. This kind of videos are one of the reasons why I like your channel
Dittos :)
Javier Castro I felt strangely pedantic after I watched
If anyone ever wanted a true definition of "Research and Development, they would only need to see this current video of yours. I for one find your videos extremely fascinating, and I have learned a lot. Thanks Matthias!
I'm not a woodworker myself, but for some reason I just love your videos and can't stop watching them!
Awesome explanation. I love these blower/dust collection videos, it gives so much insight for when I build my own from scratch ...some day.
I'm just starting to design my new shop and my dust extraction system is a top priority. This test will actually help me make some piping and hose decisions. Thanks.
As someone who worked in the heating and ventilation industry for years, this was cool to see, good job!
Mathias, thank you for doing my job for me! I was about to conduct a very similar test but this confirms my suspensions and will help my project get along faster. Thank you for your channel!
FANtastic. Oops, did I just write that?
Your work with these systems is amazing, and I am sure we are all learning something new with each experiment you perform.
I am so gonna try making one of these in the very near future.
Keep up the good work.
These last two vids have been so informative and helpful (repeating myself?). Once and engineer, always an engineer.
perhaps add smooth hose versus flexible/concertina hose to your comparison chart... tho that then brings in a whole new discussion about surface/laminar flow :)
These hoses are actually quite smooth inside. Besides, wobbly surface could have better performance, especially for curved paths. Watch Mythbusters video about golf ball aerodynamics, they've explained it quite throughly.
Even if that's the case, that may change when you add dust and other debris to the airflow.
thinking that too
Woo, that would be neat. IIRC you can get laminar flow by just putting in a whole bunch of straws in a lattice.
This was a really informative video Matthias. Thanks for making it and other ones like these! It doesn't seem to matter what topic you chose (wood, shop, home, camp, random) I always enjoy your style and learn something. Please keep making them!
You inspired me in my "this is NOT a propeller video" and this one is great as well
I have no dust collector because I ussually do woodworking outdoor. I have no skills on building this machines. I do not have those measurement instruments... but, I'm engineer, I do woodworking... and enjoy like a kid with this kind of videos. Thanks!
I remember asking for this video on a comment you left on the applied science channel. This was very interesting and surprisingly educational.
Thank you for the best explanation of how much air loss happens with dust collection systems.
I love Matthias' dust collector videos the best! They changed my life.
Thanks very much for this Matthias. I have worked on industrial dust collection/ air movement systems my whole career and i have seldom seen these sometimes counter intuitive engineering principles explained so clearly. Well done, you have a way with words (and video). Forget the pedantic types, I suspect most of your viewers, like myself, don't have any time for them either... aren't they first cousins to trolls on the evolutionary tree?
I think that these experiments you do are way more interesting than your standard (but still immensely interesting) videos.
I love your vids, Matthias...mainly because you make me think about things in my workshop that I never knew I had to think about. Thanks for keeping me on my toes!
7:53 Places "junk" inside the cyclone, aka 'Black & Decker' ;)
Ave would approve.
Actually those are both some garbage Canadian Tire house brand.
The Black & Decker pecker wrecker...
I like black and decker I am happy with my b&d impact,drill,vacuum, and circular saw
Black & Decker air flow wrecker.
Hi Mathias. Thanks for the great videos on blowers. Your timing, for my shop, was right on the money. Rod Vancouver Island
Thank you for doing these tests. It definitely helps in making decisions on things to purchase and how big of a motor to include. Fascinating....
Very useful information, and much appreciated demonstrations of things that, as you mentioned, are counter-intuitive. Thanks!
Since you keep mentioning noise I'd love to see you do an experiment with asymmetrically-spaced blades and an explanation of the effect on noise. (Awaiting classic Matthias response "Nah, too much trouble, just wear ear protection")
Favorite channel on youtube - thanks for the great videos!
Remember kids, the only difference between Science and Screwing Around... is writing it all down!
I love this comment! :D
awe
You forgot the statistics in the science department! You need a repetition of 4-5 (maybe 20) depending on the Power you want/reduction of non-systematic errors/outliers and to achieve some sort of normal distribution of the recordings. Then you may call this an experimental Science video, not just a Screwing Around demonstration video.
((but this calls for building a zillion blower houses -- I didn't count the configurations/designs/ie treatments he made so I'm guesstimating -- but then, Matthias isn't the pedantic type, unlike me))
so true
i was about to say that XD
...quoting Adam Savage without giving credit, I see...
Thank you Matthias. Another very informative video.
Matthias, excellent explanation of CFM vs. Static Pressure!
Have you had a look at using small splitter vanes between the leading edges of the blades? It looks like a very easy thing to add in and apparently helps with static pressure of backward bladed fans. (see "Impeller Treatment for a Centrifugal Fan using Splitter Vanes - A CFD approach" for more info)
hey man im thirteen and love and watch these types of channels and you are by Farr one of the best keep up the good work👌
Hi,good tutorial,I just have a shop vac on every machine,never have a problem.thanks again.from Australia.
Matthius, Again a BIG THANK YOU.
The ClearVue Cyclone uses a 16 inch impeller vs. the aveage 11 to 12 something impeller. From what I've read The CFM and I'm guessing the static pressure? is increased by impeller size. You changed the restriction of air flow in the impeller which increased or decreased noise and cfm ( Imperical units LOL!) The only thing you left out of your experiment , I believe, is reducing the space from the impeller to the shrowd/housing?
I have used my own tests with an anemometer and confirmed loosing more than half the cfm that comes out of my Thein separator, which also reduces the cfm. I knew that from just listening and watching and checking suction.
My DC is an older delta 1.5 hp. Checking it out I found the impeller to be fairly straight like the old washing machine agitators The spiral experiment you did confirmed my thoughts. I'm going to re-watch your video as it helps make Bill Pentz's information more concrete.. I'd already figured I have to increase the size of my main feed and decrease the resistance of air flow by eliminating the crrigated smaller 4 " hose . Size of my motor limiting pipe size to 6 inches.
Another question or thought that came up as I examined the shroud or housing is the 6 inch connector reduces down to around 5 and a half inches. Is the venturi principle in effect and if so how?
Since static pressure is the main limiting factor, it would be interesting to see how two impellers in series perform.
this is how most vacuum cleaners work, 3 to 6 platters stacked up in series.
Most car fans have a double inlet and a double wide impeller, mounted on a plate in the center. More parallel than series tho
Now you have me curious about piping. Is rigid piping with smooth walls going to make a big difference over the ridges of flexible tubing?
From what I've read so far: flexible tubing with its ridges introduces a lot of pressure drop especially in any bends. Ironically in HVAC systems all the bends ought to be done with rigid smooth walled piping if possible but you can use flexible tubing for the straight runs (and nothing else) if you want due to its ease of transport and installation!
I think so.
It seems to me HVAC guys just run the flex stuff cause its easy and efficiency be dammed cause its not their money running the system.
Precisely. Not to mention leaky ducts leading to loss of heat/cool, and over- or undersizing equipment resulting in a host of other problems...
Flex will always bring more disturbance than smooth wall. In ducting its key to run your main through the house and then use as little flex as possible to connect vents in odd areas. We do see a lot of flexi duct being used now but you as the consumer have a voice. It has to do with how much you are willing to pay and proper planning for a project. Shortcuts always cost you more money in the long run!
nice, really enjoyed the series. Was going to do something similar to continue building the dust collector, but don't have enough time. Thanks for doing the experiment for me :)
Very useful information and great detail! Thanks for taking the time to share this. I am making a localized fume fan for welding and had questions that your video answered quite well! Thank You!
دائما ما تبهرنا انت مبدع جدا وانسان خلوق اتمنى لك التوفيق ❤
I have couple of ideas.
Test some variables:
Distance from lid to impeller.
Size of inlet of impeller.
Impeller with and without top ring.
Fix description:
eirflow->airflow
Moe->More
I will leave those up to you. To me, the answers to these are too obvious to warrant experiments.
We don't want answers, we want experiments.
The mob have spoken!
Thanks for the video. Extremely interesting. Can't wait see what you test next with this setup.
Amazing work Matthias, excellent video.
Thanks for performing the experiments.
The results are very interesting.
To find the most efficient shape for a fan, just look at fans? The blades are in a spiral but they're also curved diagonally.
Airflow fans use +-12 smaller blades with gaps between the blades so air can more freely flow through it. Air pressure fans use +-6 bigger blades and are spaced closer to each other so the air builds more pressure before it is released. The designs aiming for a mixture of both use +-6 bigger blades with extra gaps between.
From what I've observed, forwards facing curves are more efficient at producing high outlet pressure while backwards facing curves are more efficient at producing high inlet vacuum levels. So, for a dust collector, backwards facing is better.
These are my favorite kinds of videos from you!
Brilliantly illustrated!
I'm a pedant, so I looked up centrifugal force before making this comment.
Great video Matthias!
Queensland, Australia has an interestingly shaped blower at the moment.
sucks to be there.
Haha... :(
Godfrey Poon I don't understand
Severe tropical cyclone Debbie...
Joel Pekkanen oh, jeez, okay
I was planning to make an heat exchanger, and doing some guestimate, I figured that the pressure was an huge factor, and caused an huge flow loss. I'm still looking for some inexpensive blowers for it, and I can't find anything with enought CFM and pressure. I might be forced to actually stack two, one on the intake and one on the outtake, just to get enought pressure... A royal PITA for sure.
One of your best videos!
Fantastic tests, Matthias. Thank you.
Nice! Good example for Engineering student's final projects.
A smooth flange on the inlet (or outlet) of pipes also reduces the airflow resistance quiet a bit. Especially like your cyclone inlet. It also reduces noise because there is less turbulence.
edit:
What's even a better idea, is using a tapered section from the full width of the cyclone to the width of the pipe.
Oh, and it's pretty much well known that these flexible pipes/hoses have a very high flow resistance because of their shape (curved) and the fact that they have such thin walls (move/vibrate easily).
They need to be short as possible and connected to something like a smooth PVC pipe.
(Are there any flexible pipes with smooth inside walls?)
Great experiments. Really enjoyed watching this.
the difference in the sharp edge in the spiral housing comes with pressure build up at the blowing side, as does most of the benefit of the housing itself.
that being said, since you have made a rather robust blower, wouldn't it be better to blow trough the cyclone instead of sucking trough it? this would mean getting dust in the blower but it looks like it can handle that, plus the dust wouldn't pile up in the high flow areas. building pressure is easier than removing it, since the air needs something to push against to impart energy, building 0,3bar abs requires about as much energy as building removing another 0,1bar from that, given a closed volume. then again it might make 0 difference given the large restriction of the hose and this device working more on mass flow than pressure (though as you pointed out, pressure is still important)
you could try fewer or less fins on the fan
changing the shape of the fins
adding a dome or cone in the center
trying sharp or dull edges, since most fans have a thick body but sharp fin edges.
polished or rough / soft surface on the fins (a pc fan manufacturer used some sort of fleece on the fins to reduce noise.)
You should try to get your hands on a blower for a small bounce house. I have one left over for my sons bounce house from when he was a little boy... thinking about making a dust collector for my sanders with it.
Love the new data. I wish there was RPM data in this test too, but having the anemometer close to the inlet I agree is a much better spot. Maybe the next time you can pinch down the diffusing section axially, and have it diffusing to a bigger diameter before entering the volute.
great video ,,,, explains a lot , the length of flex hose will probably effect it as well ,,,, seeing that the hose had the biggest resistance ,,,,, would be nice to see the resistance from 90 deg elbows and 2- 45 deg and flex pipe like for a full shop dust collection set up
Matthias thank you I learned a ton from this video. Thanks a mill
Wow, this was intense. Very educational.
I really appreciate your scientific method!!
With a centrifugal compressor it probably is indeed most efficient to collect the air equally from every side of the impeller. This arrangement would be kind of like in early British and American jet engines which used centrifugal compressors - the air was pushed into ducts laid out around the compressor, and into the combustion chambers, and then through the axial turbine that powers the compressor. But, it would make for a rather complicated design with a lot of ducting, and the ducting itself could actually end up hinder the airflow more. Most centrifugal compressors used in turbochargers have the spiral or snail shell-like housing, so probably the simplicity from having one outlet outweighs the advantages of multiple outlets set equally around the impeller.
The most efficient housing would be round in shape of impeller.
And gap between housing and impeller should be just the right distance.
Good luck
It would be interesting to see similar experiments where you vary the height of the impeller blades, to see how that effects pressure and power usage.
David Smith, I can definitely tell you it will increase power consumption.
Brilliant! - Very illustrative and informative.
This is why I love your videos so much!!! The day you stop learning is the day you stop breathing!! #NeverTooOld ;-)
I was going to suggest that maybe you try curving the inner wall of your spiral but that would just create more surface area and likely increase static pressure. After seeing you put stuff into your cyclone and air flow increasing, I now think maybe you should try channeling your spiral chamber by puting a divider through all or part of your spiral chamber to see if that increases air flow.
Nice and very useful experiments. Thank you for sharing!
You saved me a lot of work
Very nice explanation, good work!
Wonder if a larger diameter cyclone can would greatly benefit the system? I'm now going to look at changing my hose system to use a few short pieces of flex interspersed with solid sections of pipe. My shop layout can support this, YMMV.
Restricting the size of the hose would also improve air pressure, maybe you could experiment with that, I thought also something similar to a beater bar to break up the path of sawdust/chips like an upright vacuum uses would help with air flow without increasing motor size and/or suction either, also would agitating the air flow by interrupting suction possibly by using an elliptical blower or one way valve make a difference? but as a last resort wouldn't just increasing the brute force of the hp/amps of the motor help with atmospheric pressure?
You should look at air handler blowers. They use squirrel cages with the curves in the direction of rotation. Opposite of a water pump. It comes down to if you want high CFM or high Static
I made some experiments with cyclones and airflows myself and came to an interesting conclusion:
The diameter of the cyclone is surprisingly irrelevant. I thought a smaller cyclone would make for faster rotation and thus for more resistance but I tested three variants from 400mm to 590mm diameter and they were pretty much equal. Also there wasn't much difference in their ability to catch the dust. So I went ahead and ordered one of the totally overpriced dust deputies (125mm inlet version) and was really surprised: With that cyclone the air flow almost doubled. I don't know why the air in there rotates so much more "efficient" but it has a lot less resistance and I don't see a difference in it's performance yet. Still most of the dust goes into the bin. So it seems to be a good product, but the price... nah. But if someone here reads this and is thinking whether the effort of building one on your own is worth it: Yes, it is. Marius Hornberger has some videos about it. Hope this helps. Took me several days to build all those cyclones. For separation it doesn't matter what design you chose, but for airflow: Use the cone shape. Wish I could explain why.
Rainer Zufall, Marius, and Matthias have explained this in older videos to some degree. Also Phill Thien's website explains why the baffle has less air flow, but keeps the dust rising out of the collection bin when it gets almost full. Basically, the baffle creates a positive pressure lobe at the center, causing a lot of resistance. Well, that's the best way I can explain it.
I only know all the videos from the first two :) At least I cannot recall any comparison but they have a lot of videos and I have a bad memory so I may be missing something. But today I want to add: Just in case someone wonders how good the dust deputy is at separating fine dust from 120 grit sanding: It is pretty much 60-70%, which I think is really good. Did a lot of sanding today with my drumsander. 30% goes to the filter but considering we are talking about really fine stuff I think that is good performance. I wonder if you can get more performance with another setup. With the good airflow a two stage cyclone would be possible but will it really help... hmmmm.
Great info for dust collector projects.
I realize I am late to commenting on this video but was wondering if the shape of the cyclone matters? A lot of the commercially available cyclones are cone shaped with the exhaust at the top, where as yours is just a cylinder? Would the cone shape help push the air up towards the top and therefor decrease restrictions?
Very interesting, this has been very helpful thanks for a great video.
have you tried making a stater? also, this should work differently when on the exhaust port vs on the intake for a pressure reading. considering your readings i would make a wheel that more closely matches your system, thinner and larger diameter. should give the benefit of having more differential pressure and less noise. but you wont have the mass flow when you disconnect the hose ect.
Great, now my lungs are cleaner... but my ears are dead...
You should look at making a muffler for that loud dust-collector! It'd be neat
Have you ever compared the static pressure at the inlet to the pressure you could obtain from a venturi? I've always wanted to experiment with making a venturi-style dust collector, that way the blower doesn't suck up any dust and debris, it simply blows the air across a venturi tube which does the real suction.
You need a compressor for this to work. A really big compressor, because the venturi is very inefficient.
Another awesome video from Matthias! The take away for me, since I want to build a leaf vac attached to my ride on mower, is just build it. for that purpose it seems like all you care about is flow and not pressure. the push lawn mower that I'll sacrifice will have enough flow for even wet leaves since I'll have the ride on mower helping. no need for special housing, just mount it on the trailer and cover with a bed sheet(like the video Matthias already made but without the housing).
any thoughts?
I'm sure it's been said but I would love to see a comparison of differing lengths of solid pipe and flex pipe with the same length run. I'll be honest most of this video was over my head but I'm sure once I'm working on a comparable project I can refer back to this and get more necessary information.
Matthias, If placing obstructions in the cyclone path increases airflow, then would you do a video on different shapes mounted in the cyclone bay in an attempt to optimize pressure. Please
Possibly a cone shape or perhaps a polygon. I'm very interested in this because my shop is a literal garden shed measuring 10' X 14' and I have absolutely no spare room, so I need my Home Depot Bucket head vacuum to work better than it does currently.
Adding obstructions to the cyclone renders it useless. So you might as well remove the cyclone then.
Awesome video! every day is a school day!
I really like experiments. Thanks for sharing yours!
Thank you for the great demo. However I wished you also showed the change in static pressure at the outlet. For all the applications when you need to pressurise a space. Can you please show that in a future video. Only you can do it 😊
Hello Matthias,
First of all, I want to thank you for your extensive and educational videos! They are truly amazing! Very useful, especially now that I'm planning to make my own fan. Secondly, I have a question: Have you ever considered making a double suction blower? And if not, why not?
Greetings from Holland!
Try using a smooth bore inlet pipe so there is no turbulence created by the corrugation in the pipe. also aircraft reduce friction/turbulence by the outside being polished so coating the inside of the components with a low drag coating may help?
That is a lot of good info! Thanks. I will have to watch this again to make sure I got it all. 😁
I had a similar issue trying to lengthen a AC venting hose in my bedroom. It came with like a 10ft hose, and I tried to add another 8 feet or so, and it just couldnt evac the hot exhaust worth jack all. Go back to the factory length and it was cold, add my extra 8ft, the room barely got cool.
if you wanted a LOT of static pressure it seems you would need a really big blower. but noise and power consumption would obviously increase, and its less efficient for the same motor size. Im wondering if there is a series or parallel configuration where you could run two smaller blowers, and generate the same static pressure of a single large blower. But both motors draw less watts combined than a single motor.
okay here's my scenario it doesn't really involve joyner's planers or table saws or any of the wood dust collection that you're dealing with my situation is dealing specifically with dust collection from a four and a half inch Grindr using 36 Grit sandpaper and it produces an enormous amount of dust so much it covers everything in the shop and I guess I was just trying to find something that had an enormous amount of suction that could deal with the situation.
fantastic experiment and implementation
The two elbows that attach the cyclone to the blower add quite a bit of restriction. A stacked cyclone would perform better.
So the conclusion is, looking from above;
a larger inlet(?) with a smaller outlet but A third/half the radius from the west side compared to the south east to let the air spin to aid the Propeller and reduce wattage. Yet build up a better static pressure.
This means, you compress the air at the inlet and therefore create a better pressure of air which increases static pressure, no?
Bit like taking a hose of water and squeezing the entrance, which doesn't make any difference in how much water leaves the hose but it increases the pressure so you can water a larger distance.
Another experiment... inlet to outlet size difference.
thanks for taking the time to come up with this data.
I built a dust colle Collector from a Blower out of a dryer and it didn't have alot of pressure because the blades are backward curved but if I reverse it then I also have to reverse the housing but that's easy to do.
Fascinating, as usual.