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Leaf Blower power?

Old 05-06-2010, 07:03 AM
  #51  
kyleservicetech
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Originally Posted by HX3D014 View Post
But, being centrifugal fan. that would be quite a bit of force pressure around such a small radius. that's about 6267G's
Wow, 6267 G's? That's far higher than what we see on our typical model airplane propellers. And they are not made from cheap plastic.
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Old 05-06-2010, 07:55 AM
  #52  
Larry3215
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Originally Posted by HX3D014 View Post
are you saying that because the first delta V is /2 ?

if so. it is not a worry. it is still a cumulative figure.

lets say it was 100kph for the first example

so 100/2 = 50
50*100 = 5000

now lets raise the 100kmh by 10% to 110kmh

so 110/2 = 55
55x110 = 6050

6050-5000=1050
and 5000/1050=4.76190
100/4.76190=21

Bryce

Lets plug some real numbers into the actual formula.

Lets choose a prop diameter such that the pie/4 x diameter x air density = 1 to keep things simple.

Lets also say the inlet velocity is 1000 and the delta = 100

(1000 + 100/2) x 100 = 105,000

Now increase the delta by 10%, remember the inlet velocity stays the same.

(1000 + 110/2) x 110 = 116,050 or roughly 10.5% more.
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Old 05-06-2010, 08:15 AM
  #53  
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You guys are both right, just different scenarios.

Bryce, you calculated static % thrust increase.

Larry, you calculated thrust % increase at a forward speed of '1000' (whatever the units are).. So the answeres are obviously different.

Fact is if you can increase velocity AND keep flowrate the same then yes thrust will increase. In the real world as larry pointed out there is no free lunch; when you restrict the outlet nozzle you increase back pressure on the fan and the mass flowrate decreases. If power and efficiency are the same then due to the V^2 relationship between velocity and energy a small increase in velocity will cause a larger (V^2) drop in mass flow, so restricting the outlet causes thrust to decrease, at least in the static case.

Larry was quite correct in that maximum static thrust, all other factors being the same, is found when the outlet is largest.. that's why big props make more static thrust than small ones watt for watt and also why EDF's tend to make less static thrust than props watt for watt.

Centrifugal fans operate much more efficiently at lower flows so some outlet restriction will be optimum but i would suspect that the nozzle size on the leaf blower is already close to the best size it can be. They are after all designed to optimise thrust in order for that thrust to move leaves.

Steve

Last edited by JetPlaneFlyer; 05-06-2010 at 08:54 AM.
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Old 05-06-2010, 09:03 AM
  #54  
HX3D014
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Originally Posted by kyleservicetech View Post
Wow, 6267 G's? That's far higher than what we see on our typical model airplane propellers. And they are not made from cheap plastic.
thats G's like in Gravitational.

Curious, Why dose the inlet velocity stay the same?
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Old 05-06-2010, 09:18 AM
  #55  
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Originally Posted by JetPlaneFlyer View Post
Centrifugal fans operate much more efficiently at lower flows so some outlet restriction will be optimum but i would suspect that the nozzle size on the leaf blower is already close to the best size it can be. They are after all designed to optimise thrust in order for that thrust to move leaves.

Steve
Makes me want to rip one apart and do some testing.
I have a feeling that they are not quite like an Axial flow system. The pressure variations warrant further enquiries.
Putting that on my list of to do's. Just for personal Education
Bryce.
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Old 05-06-2010, 09:35 AM
  #56  
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Thanks Steve. We can always rely on you to keep the science and math accurate

I should know better than to argue anything more than simple addition anyway. Its been way too long since I was in school
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Old 01-10-2015, 05:55 AM
  #57  
Witiontis
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Makita BBX7600N 75.6 CC 4-Stroke Backpack Blower is the latest best leaf blower brand known to me so far.. It has padded shoulder straps and ventilated back panel with lumbar support for improved operator comfort. I am having this from past 6 months .. It is easy to start, not as loud as I thought it would be and very powerful too
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Old 01-10-2015, 06:40 AM
  #58  
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Originally Posted by Witiontis View Post
Makita BBX7600N 75.6 CC 4-Stroke Backpack Blower is the latest best leaf blower brand known to me so far.. It has padded shoulder straps and ventilated back panel with lumbar support for improved operator comfort. I am having this from past 6 months .. It is easy to start, not as loud as I thought it would be and very powerful too
You sir, have astounding clarity on what this website is all about! Thank you for your contribution!
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Old 01-10-2015, 07:07 AM
  #59  
pizzano
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Originally Posted by Witiontis View Post
Makita BBX7600N 75.6 CC 4-Stroke Backpack Blower is the latest best leaf blower brand known to me so far.. It has padded shoulder straps and ventilated back panel with lumbar support for improved operator comfort. I am having this from past 6 months .. It is easy to start, not as loud as I thought it would be and very powerful too
Yaa......and the use of them has been prohibited by many municipalities in and around public property for several years now in So. Cal.....wonder why....?

Disruption of air quality
Violation of Noise Ordinances
Polluting storm drain systems

The list goes on.....and the post is really off topic......
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Old 01-11-2015, 04:55 AM
  #60  
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Originally Posted by BroncoSquid View Post
You sir, have astounding clarity on what this website is all about! Thank you for your contribution!
He probably didn't even look. They just google the name of the product they're trying to peddle, and then spam wherever they can.
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Old 08-01-2017, 11:21 AM
  #61  
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How you Do that! I mean leaf blower engine use for the plane?
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Old 08-01-2017, 12:56 PM
  #62  
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Originally Posted by Daniel_Vigil View Post
How you Do that! I mean leaf blower engine use for the plane?
This is a very very old thread and died more than 2 years ago ....

Nigel
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Old 05-07-2019, 08:19 PM
  #63  
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Among the products mentioned on the list, which one is the best?
https://bestairpurifiers.website/best-backpack-leaf-blower/
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Old 05-07-2019, 08:27 PM
  #64  
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Who can tell the best product among those listed on this site?
https://bestairpurifiers.website/bes...k-leaf-blower/
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