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Title: Propeller-thrust ratio Post by: Aravind298 on August 22, 2017, 08:44:26 PM Has anybody ever tried to map the thrust produced by each unit cm of the propeller? Like at which place of the prop. the most thrust is produced and at which place the least?
Also anybody with experience in propeller designing may PM me. Thanks :) Title: Re: Propeller-thrust ratio Post by: swapnilnimbalkar on August 23, 2017, 10:46:07 AM I think thrust produced by a propeller is even at all given points.
Since tip of a blade moves faster than the part near center, that is the reason why blades are more inclined towards the center. Title: Re: Propeller-thrust ratio Post by: pnkyjs on August 23, 2017, 01:57:20 PM very nice idea, there is a difficulty in mapping such a property w.r.t. the propeller because after cutting up a propeller into single unit , this single unit would not behave in same manner as when this unit works when attached to the entire propeller . so best way would be to set up an arrangement in a wind tunnel and rotate the propeller in streamlines of smoke and put many sensors radially outward at varying distance from centre to measure the pressure differences. Then a clear picture would emerge at which position that particular propeller is most efficient. Also the efficiency points would change for varying RPM . It would be interesting to also find the pressure variation in moving airflow as opposed to a standstill airflow in front of the propellor.
Title: Re: Propeller-thrust ratio Post by: pnkyjs on August 23, 2017, 01:58:37 PM my 10cents of gyaan !
Thanks. Title: Re: Propeller-thrust ratio Post by: Aravind298 on August 23, 2017, 07:53:51 PM @ Swapnilnimbalkar, I don't think it's same throughout the propeller. Since you can see the surface of propeller is not the same throughout.
Anyways, I'll be conducting some tests :) Title: Re: Propeller-thrust ratio Post by: Aravind298 on August 23, 2017, 07:55:09 PM @pnkyjs, that was really informative! Well I can't afford to test it in a wind tunnel, I'll try my best to create a similar environment to test the propeller.
Title: Re: Propeller-thrust ratio Post by: madaquif on August 24, 2017, 02:04:24 AM http://www.instructables.com/id/DIY-Wind-Tunnel-20-Project-Paperclip/
follow this to know the exact results... kindly share your experience if you happen to build a tunnel.... gud luck. Title: Re: Propeller-thrust ratio Post by: swapnilnimbalkar on August 24, 2017, 11:52:22 AM @Arvind298
just googled it, found this, it may be relevant http://www.explainthatstuff.com/how-propellers-work.html Read this "Why a propeller has twisted blades" Title: Re: Propeller-thrust ratio Post by: Aravind298 on August 25, 2017, 12:28:18 PM Thanks to Swapnilnimbalkar & mada! What I thought of, was to measure the thrust produced by every cm. of the propeller. Each centimeter of thrust will be measured through a separate precision weighing system.
But here's the downside: 1)I'm not sure how much efficient would it be, but I just wanted a ratio b/w each part of the propeller. 2)Lots of weighing machines would be needed (like at least 5-6 pieces). 3)The configuration has to be changed at will for each size of propeller. 4) Have to spend a lot of time in it :P |