Need help resolving a physics claim.

[Skeptic Ginger]

This is really an invitation to join the thread on the Dyson fan and weigh in on his physics claims. I know there are experts in this field in the forum tand I would love to find out the truth about the claims.

Watch the Youtube video on the second page of the thread where Dyson makes his claims that his fan "amplifies the air in 3 ways".

This is an interesting fan, looks nice, it's a conversation piece. But Dyson goes on to claim the fan's design "amplifies the air" and I think that claim is false and only a marketing gimmick. Other people in the thread believe his description of the physics involved is true.


I'm willing to reconsider if someone who knows more about his claims about this fan can explain them. My current opinion of the man is he uses these marketing flimflams to promote his products. I don't doubt his expertise and his designs are clever. But he markets himself and his products as advanced engineering with technological breakthroughs. And I find that description to be just a gimmick.

 

[Dr. Trintignant]

The problem is that "amplification" of air doesn't mean anything. Dyson's marketers are therefore free to use the phrase however they want. It appears that they use it to mean the conversion of a low-volume, high-velocity air stream into a low-velocity, high-volume stream (which is what you want in a fan). And the fan does in fact accomplish that.

I generally agree with the sentiment that this fan is largely marketing over advanced technology, but to say the claim that it "amplifies" the air is false is wrong, because the statement has no real truth value to begin with. If you want to show that Dyson is lying, you need to focus on the more physics-based claims, such as those about viscous shear.

- Dr. Trintignant

 

[Roboramma]

The problem is that "amplification" of air doesn't mean anything. Dyson's marketers are therefore free to use the phrase however they want. It appears that they use it to mean the conversion of a low-volume, high-velocity air stream into a low-velocity, high-volume stream (which is what you want in a fan). And the fan does in fact accomplish that.

I generally agree with the sentiment that this fan is largely marketing over advanced technology, but to say the claim that it "amplifies" the air is false is wrong, because the statement has no real truth value to begin with. If you want to show that Dyson is lying, you need to focus on the more physics-based claims, such as those about viscous shear.

- Dr. Trintignant

I disagree: he's using the term, so he obviously intends it to mean something. He intends the impart some sort of idea to the people who hear him say that his fan amplifies the air. The question is, what does he intend them to think? Whatever it is, that's his meaning.

 

[Professor Yaffle]

I'm no physicist, but I like Dyson - he seems to have a genuinely innovative way of looking at things. The air multiplier thing is probably just the best way he could describe what happens with the fan, but in layman's language.

It might already be posted in the other thread, but here is Dyson talking about the fan:

http://www.telegraph.co.uk/technology/news/6314107/Dyson-bladeless-fan-how-it-works.html

 

[Professor Yaffle]

BTW - after having read the thread now - I have to say that I have been using Dyson vacuum cleaners ever since I used my first one. They are so much better than the ones with bags. Interestingly, even though the best thing about them is that the suction power doesn't decrease so much as it gets full, it seems that the bagless format is what has become popular with the public - so that's what the advertising latched on to.

So have they not taken off in the US? Here, its getting to be so that the word "dyson" is being used generically, much as "hoover" was used in the previous era of vacuum cleaners.

 

[ParrotPirate]

-Slight derail- Yes, we have Dyson vacuums here in the States, and they seem to be gaining popularity. They are somewhat expensive, though. I hear they're well worth it, but I'm going to wait a bit yet, I think.

 

[steve s]

But Dyson goes on to claim the fan's design "amplifies the air" and I think that claim is false and only a marketing gimmick. Other people in the thread believe his description of the physics involved is true.

What Dyson means by "amplify" is that the amount of air passing through the circle is greater than the amount of air that is passing through the impeller. That's because the ambient air is drawn through the ring by the lower pressure air leaving the slit in the ring.

Steve S

 

[Dr. Trintignant]

The question is, what does he intend them to think? Whatever it is, that's his meaning.

Didn't I explain this? As far as I can tell, they use the phrase to mean the conversion of a high-velocity, low-volume air stream into a low-velocity, high-volume air stream. It "amplifies" the volume of air moved.

I suppose I should have said that the phrase as used has no inherent scientific or technical meaning. If he were selling electronics parts or stereo components, we would expect certain things if he called them amplifiers, and it would indeed be false advertising if the products did not have certain behaviors. But in the context of fans, amplification has no expected meaning.

- Dr. Trintignant

 

[Ziggurat]

Didn't I explain this? As far as I can tell, they use the phrase to mean the conversion of a high-velocity, low-volume air stream into a low-velocity, high-volume air stream.

Actually, what you said is not necessarily the same thing. The problem is that for flow, what you want to characterize it is not volume, but either flux (volume per unit time) or cross-section (flux divided by velocity), making your statement ambiguous. The flux can be calculated as the product of flow velocity times a cross-sectional area, and so for a given flux, a low velocity will have a large corresponding cross-section, and a high velocity will have a small cross-section. It's easy to convert from high-velocity, low cross-section flow to low-velocity, high cross-section flow, without changing the flux. This might count as cross-section amplification, but it's not flux amplification. The trick with the dyson fan is that the total output flux (not just cross-section) is actually significantly larger than the flux through the impeller. That does take some fancy design work, and I think it's justifiable to call that "amplification" (though the marketing doesn't make it very clear that it's the flux which is getting amplified). Whether or not that really produces a better fan (or if the improvement is sufficient to justify the price) is a separate matter.

 

[Ziggurat]

BTW - after having read the thread now - I have to say that I have been using Dyson vacuum cleaners ever since I used my first one. They are so much better than the ones with bags. Interestingly, even though the best thing about them is that the suction power doesn't decrease so much as it gets full, it seems that the bagless format is what has become popular with the public - so that's what the advertising latched on to.

So have they not taken off in the US? Here, its getting to be so that the word "dyson" is being used generically, much as "hoover" was used in the previous era of vacuum cleaners.

They're popular in the US, but they're significantly more expensive than most other vacuum cleaners, so they're sort of a luxury brand. And "never loses suction" has been one of the key selling points in their advertisements here.

But nobody really uses "dyson" or "hoover" as a verb, and least not around here. But a lot of people would probably understand what you meant if you said "hoover" as a verb.

 

[Ernie M]

This is really an invitation to join the thread on the Dyson fan and weigh in on his physics claims. I know there are experts in this field in the forum tand I would love to find out the truth about the claims.

Watch the Youtube video on the second page of the thread where Dyson makes his claims that his fan "amplifies the air in 3 ways".

This is an interesting fan, looks nice, it's a conversation piece. But Dyson goes on to claim the fan's design "amplifies the air" and I think that claim is false and only a marketing gimmick. Other people in the thread believe his description of the physics involved is true.


I'm willing to reconsider if someone who knows more about his claims about this fan can explain them. My current opinion of the man is he uses these marketing flimflams to promote his products. I don't doubt his expertise and his designs are clever. But he markets himself and his products as advanced engineering with technological breakthroughs. And I find that description to be just a gimmick.

If flimflam is meant as a nonsensical or insincere talk, I disagree with your comment.

James Dyson has done extensive research, development and testing to bring the Dyson Air Multiplier™ to market. It seems you have a disagreement with the words used to describe issues surrounding the airflow/rate of his fan, and how this is achieved. It is my opinion that the semantic, syntactic, and pragmatic meanings used by James Dyson make sense, and are sincere. Look at the amount of work that he put into making this product.

The man works in a creative field. In some respects, the word choice, such as multiplies the airflow, used to describe the Dyson Air Multiplier™ is simplified and tries to convey the gist of what it does/how it works. I don't see that James Dyson is trying to purposely mislead consumers. He's trying to convey in simple terms, what/how his fan works.

PLEASE EXPLAIN
If you want to nitpick word choice, look at the following examples of products and see how much truth and accuracy there really is, please explain some of the following advertising slogans:

Tastes great, less filling. (Miller Lite beer)
How can Miller Lite be "less filling" if it is a liquid, and has the same volume as a beer that isn't a "lite" beer? Won't a person drinking Miller Lite beer be filled (by liquid volume) the same amount as any other liquid of the same volume?

Good to the last drop (Maxwell House coffee)
What if someone doesn't like coffee because of the taste? If their first sip didn't taste good, how could the last drop taste good? And what does good to the last drop mean- does it lubricate your automobile engine good to the last drop?

Breakfast of champions (Wheaties cereal)
Does every "champion" in the world eat Wheaties for breakfast? Does eating Wheaties make you a champion? I've eaten Wheaties and I haven't defeated or surpassed all rivals in a (sports) competition all the time.

I think James Dyson produces exceptional, good-looking, and innovative products. You might not like the price, but look at what it takes to bring his products to market.

 

[The Central Scrutinizer]

I think it is safe to say this thread isn't going as Skeptigirl had hoped.

 

[Dilb]

I keep hearing multiplication, rather than amplification (except for a line on the website). That sounds fine to me, as his fan is designed to multiply the volume of air moved, relative to the volume of air actually going through the impeller. I have no doubt that it actually does that, as avoiding mulitplication would first be hard to avoid, and second kinda silly to lie about.

There is such a thing as a fluid amplifier, but a Dyson fan is not such a thing.

 

[CNY_Dave]

-Slight derail- Yes, we have Dyson vacuums here in the States, and they seem to be gaining popularity. They are somewhat expensive, though. I hear they're well worth it, but I'm going to wait a bit yet, I think.

I would never have bought one at full price- but the refurbished one I bought was a great deal, and just as 'new'.

Dave

 

[Soapy Sam]

Slight side issue- I have a Dyson vacuum myself. Works well- but I would not buy another bagless vacuum.

I live in an apartment. To empty the dyson, I have to tip the accumulated dust into a bag and tie the bag. Not the Augean stables- but a lot of dust is unavoidably scattered around in the process. A disposable paper bag is actually less messy .

Also, Dyson's motors run hot and have a thermal cutout which prevents restarting until it cools. Fine idea. But it would have been nice to know about before I tried rewiring the damn thing!

 

[Professor Yaffle]

Put dust compartment inside bin liner, partially close neck of bag (just open enough for your hands to be inside tip out and give a good shake/tap to the dust compartment, remove compartment, tie up bin liner. I really have never found this a problem. If I want to give the compartment a really good clean, I will go outside with it, but just for emptying its not messy at all.

 

[quadraginta]

Put dust compartment inside bin liner, partially close neck of bag (just open enough for your hands to be inside tip out and give a good shake/tap to the dust compartment, remove compartment, tie up bin liner. I really have never found this a problem. If I want to give the compartment a really good clean, I will go outside with it, but just for emptying its not messy at all.

Funny thing. I mentioned the exact same procedure, maybe with a little less detail, to the Defenders of the Bag (both of them) in the thread that inspired this one and was met with total disbelief.

I guess it sounds much more difficult than it actually is.

 

[GlennB]

Office cleaners in the UK use the Henry vacuum cleaner - or a very similar style - almost exclusively. Without bags too, although they're designed to take a bag. Emptying them (sans bag) is a pretty foul job as the filter will have a wad of dusty hair an' all stuck to it that needs shaking off, so you'd need a decent sized garden for that job and not do it while the neighbours are having a bbq just downwind of you.

Thought I'd share

 

[patchbunny]

So have they not taken off in the US? Here, its getting to be so that the word "dyson" is being used generically, much as "hoover" was used in the previous era of vacuum cleaners.

They're much more expensive than other brands, and from reviews, don't necessarily clean as well as other brands. A few years ago I bought a vacuum cleaner (can't recall brand, and I'm not at home) for much less than half what Dyson would cost, and it was rated much higher. I've not seen why I should pay that much for a Dyson yet.

 

[Ernie M]

Slight side issue- I have a Dyson vacuum myself. Works well- but I would not buy another bagless vacuum.
[...]
Also, Dyson's motors run hot and have a thermal cutout which prevents restarting until it cools. Fine idea. But it would have been nice to know about before I tried rewiring the damn thing!

Soapy Sam, I know you are an intelligent man, so don't take this the wrong way, but have you cleaned the motor prefilter or post-filter?

Clean or new filters may not fix your situation, so take a look at this Web page regarding a Dyson DC07 and scroll down to the post titled, "Best Solution" posted on 30 Sep 2008 by "gualo" for other suggestions to try to remedy the thermal cut-out problem.

Or, did your rewiring already fix the thermal cut-out problem?