New Question About Axial Blower

What is your cfm requirement?

Not axial. (But then, I don't know why the fixation on axial.)

Not really. It will use less power.

Help for calculating the impeller diameter or speed for a new flow rate

Pump Affinity Laws - Engineering ToolBox

Dear Lyn- My concern isn't now about energy consumption.

Now I need to know if the design for an axial blower like I need is simple enough , so I may draw it by myself and then give it to a technician who will do the job ,without getting bankrupt!...

I'm asking this because I couldn't find anything like what I need on the shelf, I think that's because there is no commercial demand for such a blower.

It is difficult for me to imagine, "the lowest air volumetric flow rate that is possible" being anything other than zero.

Without some idea of the work that this, "lowest air volumetric flow rate that is possible" is required to do, an answer will be difficult to produce.

Are you lifting a feather? Inflating a balloon? Cooling something?

Well- I try to answer without disclosing anything important: I do not need pressure, I need mild vacuum, but since in my question the month ago, I was answered that the same blower that will create 1.5 atmosphere pressure, will create on the suction side 0.5 atm.[or I misunderstood?]. So I want to create a dynamic low vacuum, dynamic -means it is in constant interaction with the surrounding atmosphere.

If anybody makes a subminiature diaphragm pump, that might satisfy your needs. Still no inkling of flow required.

There are basically two types of air pumps, volume and pressure. Volume pumps generally have an impeller to push air, whereas pressure pumps have pistons and cylinders.

I have no idea what you are trying to do, but if you are trying to evacuate a sealed chamber, you should probably use a piston (pressure) pump. Once the desired vacuum is achieved, you can shut the pump off and it won't leak air back in.

Dear Rixter- I'm not sure, but there is a good chance that I'm much older than you [born 1938], so I allow myself to answer you little beat patronizing- do you really think that any person who has some innovative idea based on aerodynamic will not know the basic physical facts and the engineering devices that you suggested here?!

Not speaking about the 2 aerodynamic engineers that I wrote that they support me, but temporarily not available to me.

And few words for all the other people who spent lot of good will but...

I introduced here a question about physics and engineering, but most of the people preferred to "push" me some devices based on aerodynamic but that couldn't help me, because they didn't have the faintest idea what my idea is!

Maybe that it will be impossible to solve all the problems that involve my idea, but I've done my best to pick up as much relevant information and knowledge which is relevant.

I wish all you all the best.

"because they didn't have the faintest idea what my idea is!"

Whose problem is that?

Maybe stage a few of these?

They're cheap enough.

Can't see that hitting 1.5 atm..

Read on.

If you don't need much flow rate, a simple bicycle pump would work. There are electric ones available that automatically shut off at a pressure setting.

There are small aquarium (diaphragm) pumps to consider. With a little modification you can have it vacuum before 10am mon.

Unless there is a strong need for axial? Leave the aerodynamic guys out of the equation.

Sometimes "hire a pro" is overkill

"... I asked if it is possible to gain air pressure about 1.5 atm"

"... all I need is air to be pressed to 1.5 atm."

"... with air pressure about 1.5 atm."

but now you're saying

"I do not need pressure, I need mild vacuum, ..."

"So I want to create a dynamic low vacuum, ..."

???

I beginning to wonder if this guy is playing with a full deck.....

Given everything I have read in his other threads and what questions plus what bonehead level understandings of basic science, physics, and general practical engineering concepts he has show himself to have I have suspicion that 'not playing with a full deck' is way to polite of description.

'Plastic spork in a sword fight' or 'Tricycle in a Nascar race' would be my views.

It was my fault- I should tell you from the begining that I want 0.5 vacuum.

I thought that since a fan that can create 1.5 atmospheres pressure, may create from its suction side a 0.5 atm. vacuum.

Freudian. Wants vs needs.

There seems to be a plethora of battles going on in these forums pertaining to that. Seems to be why nothing is being accomplished, actually, in what is essentially a volatile think tank.

Make one of these and experiment.

Dear lyn- Am I not deserved to have a relevant answer for my question, or this is the way you tell me to stop to bother you with stupid questions...

Your questions are far more intelligent than many we get.

But blowers are not usually specified by inlet suction. The manufacturers would be the best source of technical data on blowers similar with designs.

The device pictured can be used to gauge the suction of any fans you may have. (or positive pressure too)

Without some idea of what you are trying to accomplish we're just guessing.

All I want to know is if the design for an axial blower that supplies n qubic meter per minute of air at 1.5 atm will be much more complex when compared to an axial blower that supplies only 1% of this air amount at the same pressure.

They will differ only in scale and minor details like motor type, etc.

By using the term "axial blower" you have defined the device that must be used, so the answer is that you can change the blade size, pitch, number, etc, but you still have an axial blower at the end of the day.

The question is about the design for each blower's blade: pushing a big amount of air at high speed requires a more sophisticated profile than by pushing a small amount slower.

Not axial.

Alternative fact.

ok- but this is a centrifugal fan, I preffer an axial.

I don't think you can get where you want to go with an axial fan, at least not easily. Moreover, none of your responses have been cogent.

Can't, but good luck.

Probably my poor english, and the lack of high education, prevented me to introduce correctly my question. I try again.[ one more challenge to overcome...] Most blowers are designed to supply a big amount of air for different purposes. If the goal is just ventilating some space, they'll need an axial fan, it will do a sufficiant job. If the goal is to supply air for a turbine, the volume of air per minute will be calculating for a certain amount of fuel to be combusted with increased pressure. Now comes my speculation: I think that it might be possible to get mild pressure [1.5 atm.] through using a fan that its blades will be posed with a low pitch. The low pitch will help to overcome the [mild] pressure that we need. The blades will be overlaped, to prevent leakage of the compressed air. For the same reason the blades must be short relative to the fan's hub, otherwise according to the perimetric velocity gap,between the blades tips and the hub, there will be big air pressure differences and air will leak. Attention must be given to the blades tips-it must be placed in a tight cylinder to prevent air leakage . But it is impossible to get high volumetric air flow on the same design! Because if we increase the r.p.m on the same design we'll get nothing more than turbulences! In summery:I.M.O- a fan with low pitch overlaped blades ,mounted on a big radius hub is the sufficient base for a low volumetric flow of air at mild pressure.

What of asking "I need to move <X cubic metres> of air per <T time interval> through a chamber whilst holding the chamber pressure at 0.5 bar. What sort of device would best fulfill these conditions?" and let the forum consider what may work best?

By placing irrelevant constraints on the solution - such as specifying that it must be an axial blower - you are more likely to end up with no solution at all.

Identify the actual problem you're trying to solve, put some numerical parameters on it, and frame the question. Avoid comparative terms like "mild," "small," "large," etc., because they tell us nothing about what these vague terms are in comparison to. Nothing whatsoever.

If the goal is to supply air for a turbine, I'm at a complete loss to help you. Turbines move a LOT of air.

Maybe a ducted propeller or fan will help, but positive air flow in not possible with either.

Ducted propeller - Wikipedia

Ducted Fan - Wikipedia

I really do not understand, why no one is answering to my first question, or to the latest. Now I'm not asking you to solve any problem for me, rather to answer me if my assumptions are correct or wrong.

If my assumptions are wrong- then please let me know it directly.

Have a nice day.

az.native

Based on what you have said, I believe that your assumptions are incorrect.

I don't give up and I'll try another argument: This time it is the ground effect. I think that the kind of axial fan that I was asking about, may be compared to the ground effect! Both phenomena take advantage of the low pitch of the wing [blade], where in a relative low velocity gain high pressure. I dare to compare in this case the lift to pressure, because I think that in the case of ground effect, it is relevant. So it seems to me that in this case, there is no difference between a rotating wing like a fan, and a straight moving wing like an aircraft! Both cases-mild pitch and low air velocity gain increased pressure!

Good thought. Would a fan with the diameter of an aircraft spinning at a low speed provide provide the pressure you need with low volume of air? It seems to me that diameter and surface area of the blades would have to be substantial.

Ground effect only occurs when the wing/fan blade is closer to the ground (or other stationary surface) than the length of the wing/fan blade.

So, if you have a one foot wing/blade it must be within one foot of the stationary surface.

I believe that we are failing to communicate.

Surprise- this time your explination convinced me.

Thank you!

Would it not be more the 'width' of the wing, than the length?

I think it has to do with the air flow coming off the back of the wing, so I guess we could say the wing is wide relative to the direction of travel.

Ground Effect - W5GW

As the airplane gets closer to the ground, this downwash is modified such that it contributes less of a vertical opposition to lift

It is important to note that downwash is along the entire trailing edge of the wing and the wing tip, it is just easier to see the wingtip vortices and use these to explain ground effect.

The pressures involved in ground effect are much lower than you require. Typically the gauge pressure in a hovercraft skirt would be 0.05psi. Increased pressure under a ground effect wing would be about double that value.

'm thinking, philologically that some languages lend themselves more to the technical side of things and others to the emotional or descriptive sides of things.

Who knows? The OP could have invented a leaf blower that might spur great innovation and help us colonize Mars.

If only the Helpful Honda people were nearby...

It's hard to tell that it was a yes/no question. You should have stated that instead of being incredibly vague and unappreciative.

no

Let the leaves fall where they may....

How much air do you need to move? "Small" amount as compared to what? This one moves a "small" amount of air

compared to this one:

If you were a little forthcoming with your needs, you might have your answer sooner. You can tell us this info without divulging anything about your project. For we know you're building a wind tunnel for gnats and that's just fine, but without some hard numbers there's really not much we could do for you.

Incorrect.

No; less complex for the larger one.

Whatever you can do with axial, you can probably do with 1/3rd the number of centrifugals - or something like that number -

Get one of these and adapt to your needs. $21.

SEKO type BLO12 single impeller two stage side channel blower draws 500mb of vacuum at delivery rate of 28cubic meters/hour. 3kW motor. Overall size fits into a 0.45x0.45x0.37m cube.

First one I looked at on the web, no recommendation implied.

Single impeller, two-stage?

Axial?

I agree that it is not what he is asking for, but if what he wants is not going to achieve his goal, I thought it might be a good idea to offer a solution that will. ½bar vacuum at ½m³/minute has an energy cost of 3kW in a proven engineered product optimized for efficiency. What he is suggesting botching together may deliver ½psi. but no way will it deliver ½bar, fans of any description are not designed for that duty and fiddling about with the blade shape and spacing is not going to change that.

My real question is, how is what you described as a single impeller, two stage blower considered two stage?

More importantly, we have no idea of the end requirement.

It's like saying I want a good cup of coffee. I know how it should taste, but I may not know how to brew it.

why didn't you relate to my post [39]?

In a single stage side channel blower the impeller sweeps air into a single channel where it is compressed and then discharged. A standard two stage compressor would feed the air already compressed in the first stage into a second channel with its own impeller which compresses it further. A two stage single impeller design still has two channels but a single impeller is shaped to sweep both channels simultaneously. The benefit is in reducing the number of parts used, so reducing the price and weight. Reduced rotating weight also increases the efficiency. The operating principle of a side channel blower is complex, relying on centrifugal force, vortex generation and narrowing of the channel between intake and exhaust to compress the working fluid (in this case air). Because the air is forced outwards by the impeller blades the inner (nearer to the axis) parts of the channels can be connected without significant leakage between channels. Think in terms of a circular housing with the inside profile shaped like a digit 3 swept by an impeller with the end of each blade shaped to match the inside of the 3. I have never heard of it being done but in theory the circumference of a single impeller could be shaped to sweep more than 2 channels so increasing compression further. Jet engines work on a similar basis, using multiple sets of turbine blades to create high compression.

Forget using an axial blower. The axial blower uses aerodynamic lift to generate the flow. At very low flow rates, the air flow stagnates over the fan blades, which stall, and your pressure drops to zero.

For low flow rates and high pressure, you are much better off using a centrifugal blower which maintains high pressure even at zero flow rate. The pressure is the result of the centrifugal force of the air as it spins in the housing.

Then you are talking about a positive displacement type of pump.

I assume you are not trying to move air into and out of a room, or other large volume cavity.

Edwards make axial vacuum pumps starting around 10K$ Talk to them

And don't forget the backing pump to keep the turbo's outlet pressure below 0.1 mBar!

Indeed.. It sure does sound like a project begging for money to be thrown. Success is measured in bankruptcy filings.

If you would be less sincere [there must be a beter word for it...] I would waste some time to tell you about some ideas of mine which were successfull [though others practiced them] Since if you would read what I wrote ,you would see that I have no many to spend, and hardly I have for my living. But that would require you to read carefully.

But I can console you - you are not alone...

So basically, you can't even answer three basic generalized questions that would have taken less time and effort to answer than what your reply to me took to write then?

Maybe he and Heidi can get together and build a levitating sand castle.

... heeeey buddy buddy.. there's a market for levitating sond castles.

Merci beaucoup...

You would waste some time? You've wasted plenty! ...and it sounds like you're ready to waste more. tcm is merely pointing out that so many here have been trying to work out your issue. You seem to be unwilling to accept that.

You've been around here long enough to know that your information is as lacking as your replies.

You won't even explain why the ef an axial fan is the only option you will consider!? It makes zero sense based on the limited information you provide. WHY!?

HERE IS THE COPY OF MY QUESTION:

Am I right that the design and manufacturing of an axial blower for low air volumetric flow rate, with air pressure about 1.5 atm. is much more simple in comparison for the same air pressure with high air volumetric flow rate?

I expected that you'll answer me 1 of the following answers:

1[ You are wrong- because...

2] You are right.

3]You are right,but...

Already been answered several places.

I know, but I wonder why educated people waste time and mental energy on irrelevant answers!

But I don't wonder why uneducated people waste time and mental energy on irrelevant questions.

Dear gurus and responders I hope in that in one of the coming days I'll meet [for the first time] an expert for fans and blowers, from the technion in Haifa. , I hope that he will help me with the problem of the axial blower. In case that it will happen, and if I succeed to get a fan like I want , I don't know yet how much it will cost. Any way- IF I'll succeeed to prove my idea, I'll let you know about it. Let me tell you that I concluded that as I introduced my question, I should emphasize that it is yet only in the stage of trying to consruct a prove of concept, and hence it doesn't matter about finite quantities of air. For this was the dominant question of the responders. I hope to get the permission of the 2 professors of the Technion in Haifa who support me, to disclose their names, but since for some reason they aren't avialable for me this week, I hope It will be done the next week If I'll get this "desired" fan, and I'll succeed to prove my idea- of course you know about it-But even I'll fail- I'll share with you al the details. Because in this case you'll be able to understand why 2 aerodynamic professors supported my idea!. So the forum of cr4 enabled me to be acquainted to some people that know a lot about physics and engineering, but...

Leave it up to those aerodynamic professors in their fancy wingsuits, jumping from their lofty towers, then.

No you are not right. You are very very wrong and apparently too stubborn, senile or just too simple to follow why you are wrong despite what multiple intelligent educated and experienced people have already told you multiple times over.

You ran a thread not too long ago asking the same axial fan related question and I gave you a very well defined example of what axial fans are capable of in their highest pressure producing form which was a jet turbine engine and if I'm recalling my numbers correctly the most powerful highest thrust capacity jet turbine engines ever produced can barely make 1 ATM of pressure.

So given that, NO, ANY AXIAL FAN YOU COULD POSSIBLY AFFORD CAN NOT MAKE 1.5 ATM OF PRESSURE NOR CAN ONE MAKE .5 ATM OF VACUUM. PERIOD.

Respected tcmtech- Is it my ignorance that made me to belief that the compressor of turbojets is a multistage axial fan?!

I wrote before that an engineer of the BSEL[which manufactures small jet engines] told me [ in hebrew!] that it is possible to design even a 1.6 atm single stage axial compressor. But it is a complex design.

I emphasized that he talked to me Hebrew, to prevent any attempt of you that I didn't understand him...

Your humble disciple

az.native

Yes they are a axial turbo fan and as far as anything that has ever been produced the only ones that can achieve your stated 1.5 ATM pressure output are massive passenger and cargo jet or very high end military engines with price tags in the tens of millions of dollars that consume incredible amounts of fuel while moving literally millions of CFM volumes of air.

So once again, until you define the actual air volumes you need to move and the space said fan system has to fit in you will not get a single answer to any of your questions.

So far all you have said is this,

" But I do not need a big mass of air, all I need is air to be pressed to 1.5 atm. at the lowest air volumetric flow rate that is possible."

Which to all of us says you obviously don't need a 50,000+ horsepower military aircraft engine that can pump 10's of millions of cubic feet of air per minute by any stretch of the imagination.

For all we know all you want to do is blow air bubbles in a large fish tank that is about 3 feet deep but have some sort of fixation the term 'axial fan' for whatever reason.

So there we go right back to the #1. question you have to answer for us. How much air do you need to move?

.1 CFM?

1 CFM?

10 CFM?

It's not a hard question to understand.

Let's also consider the amount of time the expertise in this forum is wasted trying to figure out what OP's who provide limited information about the parameters of their projects, are actually trying to accomplished and why. Most just want Cliff notes, so to speak.

But....who's fault is that? The poser's or the one's who romance the stone?