electric boat propeller

[rbaffigo]

Good morning to all and thank you for the resources you make available on this site!
My name is roberto, I studied physics, I am an artisan/entrepreneur in the areas of jewellery and furniture, I am beginning to use
rhinoceros for drawing prototypes for microfusions.. . .

but the real reason why I joined the forum and I am opening this discussion is my boundless passion for the sea:
I am riding an electric motor on a cruise sailboat, the engine will serve for propulsion and especially for regeneration. .
better explain: the engine is a three-phase permanent magnet synchronous with 4 quadrant drive, the idea is to have the propeller always in motion and always connected to the motor, depending on the wind conditions (but also of the current when you are at anchor) the motor will consume or produce energy taking it or entering it in a pack of lithium-ferrous-phosphate batteries.
would serve a propeller with a higher yield possible in the two conditions of use: the propeller must have a sort of symmetry of performance compared to the pressure conditions nothing.
I did not find any product or design that meets these characteristics and I decided to draw and produce the propeller I need... .
I don't have any problems with production, but I don't know where to start. . . .

thanks, roberto

 

[PaoloColombani]

Welcome to the forum, and the Benvenevoli look a little 'you get from another physicist who has put himself to make the craftsman/entrepreneur and who uses rhino by default (I don't think we are in many!). compliments also for your idea that for now I don't have time to commute but that I think it might be lucky for several reasons.

I would advise you to protect your idea with a patent.

 

[rbaffigo]

thanks for the welcome,
the idea of charging in navigation is not mine but already exists in several systems of electric propulsion (almost all north European and American); What I would like to patent is the propeller that optimizes this use of electric propulsion. . .
but first I have to design it, and I don't know what software to use, I think I need a specific software for propellers to draw the idea I have in mind, and also a simulation to do the first tests before constructing the propeller.

soon

roberto

 

[MBT]

I press that the only thing I know about boats is floating, but...
Why not do it with the variable incidence of the blades?
so you could optimize the angle according to your speed

 

[PaoloColombani]

one of the reasons why I have seen this idea well is that the fluid dynamic resistance (motor briefly drag) of the propeller in turbine operation could possibly be studied to correct the drought of the hull, but for this would serve a housing in mobile gondola.

as you will know better than me (since you are studying there) the operation of the propeller as a propeller differs substantially from the operation as a turbine for the fact that in the first case the speed of the fluid entering the profile of the shovel will be less than the outgoing speed, the situation will be reversed in operation as a turbine where the triangle of speed will give rise to a profile like that of the caplan turbines.
in support of what mtb says I would observe that almost utte the caplan type turbines are equipped with pitch control.

to overcome the problem of the diversity of the profile between propeller and turbine propeller I would look for a neutral and symmetrical profile (like that of a fin or like that of a drift to understand us) and not to lose too much on the performance I would reduce the profile by recovering the portance on the extension of the shovel. something that might look like the propellers of modern submarines.

on this topic it would be nice to see a user of this forum called drag (the nick says everything!) that is a naive who deals with propulsion propellers.

 

[Fulvio Romano]

I press that the only thing I know about boats is floating, but...
Why not do it with the variable incidence of the blades?
so you could optimize the angle according to your speed

variable step propellers already exist. it is necessary to optimize the yields because the motor can turn at constant speed and on the changes the step can vary the thrust. The idea of using the propeller as a turbine doesn't seem stupid. Perhaps you can think of using the principle of counter-rotating propellers: two propellers, a left and a right-handed mounted on the same axis. the principle is to avoid rotating water, but the results could have the required symmetry.

we wait for comment of dragon...

 

[KLA#27]

Good morning to all, very nice this discussion! !

I would like to ask for 2 clarifications:

- What does mobile gondola mean? ?

- an operation of the propeller as a generator in the phase of a crucible implies (as rightly has already been said) a slowdown of the flows under the hull, which involves an increase of the resistance to progress; This effect is considered negligible compared to the regenerative one proposed here? ?

thanks for the clarifications!

 

[PaoloColombani]

- What does mobile gondola mean? ?

the gondola (in English "pod") is simply a housing for external devices to the hull, an example are the motors of the dirigibles that are housed in a famine called gondola, as well as the motors placed externally to the hull in a ship, see the azipod of abb.

- an operation of the propeller as a generator in the phase of a crucible implies (as rightly has already been said) a slowdown of the flows under the hull, which involves an increase of the resistance to progress; This effect is considered negligible compared to the regenerative one proposed here? ?

no, it is not negligible because there passes the efficiency of the propeller both in generation and in thrust, so they are two transformations in which you lose a beautiful slice of energy. everything is played on the efficiency of the propeller because the efficiency of the electric machine that would like to use roberto is really very high, in the order of 97%.

 

[Exatem]

welcome to rbaffigo and compliments for his passion.
I would like to point out that I am out of place (I am in vacation, at the sea ) and I have no data with which to prove my claims.
I am not an expert in propellers, indeed, even when he had need, I turned to the friend dragon always available and punctual
but I make two considerations "from the beach".
1- all famine apses affect heavily and negatively on the efficiency of a hull. more reason on "lent" hulls like sailing boats. It is known as often used propellers whose blades fold on the hub significantly reducing the resistance to progress.
2- what mbt suggests on the use of variable step propellers, has two negative aspects. the greater mechanical complexity and the worst performance.

I do not want to demolish expectations but I see different difficulties.
We wait for the drag intervention that will enlighten us on these aspects.
Greetings to everyone.

 

[Drag]

I do not want to demolish expectations but I see different difficulties.

:frown:
what is said by exatem is unexceptionable, as well as enviable (beach to the sea)

excluding the most expensive and complicated solution, i.e. a variable step propeller, remains very little to optimize.

the space under the hull is limited, this limits the diameter of the propeller, said this according to the engine power, n° spins, speed hull (except for ski yields etc) we calculate the excellent propeller at fixed point (I mean that the max output is obtained only at those given conditions).

now we analyze the operation of wind turbine.

1) the ranges are different depending on the wind and the current, then the axial vel. varies, but we suppose it is similar to that of motor calculation.

2) the speed of rotation propeller, to the sail will always be presumed considerably lower than the motor one.

at this point the sail speed triangles highlight a vel.reultant in the profile input with a much greater inclination, in poor words the propeller should have much more step, than the motor one.

the only efficient solution -> variable step propeller

As for the palare section, I would use a symmetrical elliptical profile (type bow truster), probably seen the modest speeds, without curvature.

greetings to all

 

[KLA#27]

welcome to rbaffigo and compliments for his passion.
1- all famine apses affect heavily and negatively on the efficiency of a hull. more reason on "lent" hulls like sailing boats. It is known as often used propellers whose blades fold on the hub significantly reducing the resistance to progress.
2- what mbt suggests on the use of variable step propellers, has two negative aspects. the greater mechanical complexity and the worst performance.

what is said in point 1 is the same doubt that it had come to me, expressed more professionally...:finger: but I disagree on point 2, in particular on the worst performance that you would get using variable step propellers. . I think it's the opposite... as I always have a project condition with maximum performance and in off-design conditions I have the possibility to reduce losses.. .

Hello everyone

 

[Drag]

in particular on the worst performance you would get using variable step propellers

in the project point is so, better propeller to fixed blades

in off-design conditions I can reduce losses

This is true

greetings

 

[Exatem]

:frown:
what is said by exatem is unexceptionable, as well as enviable (beach to the sea)

excluding the most expensive and complicated solution, i.e. a variable step propeller, remains very little to optimize.

the space under the hull is limited, this limits the diameter of the propeller, said this according to the engine power, n° spins, speed hull (except for ski yields etc) we calculate the excellent propeller at fixed point (I mean that the max output is obtained only at those given conditions).

now we analyze the operation of wind turbine.

1) the ranges are different depending on the wind and the current, then the axial vel. varies, but we suppose it is similar to that of motor calculation.

2) the speed of rotation propeller, to the sail will always be presumed considerably lower than the motor one.

at this point the sail speed triangles highlight a vel.reultant in the profile input with a much greater inclination, in poor words the propeller should have much more step, than the motor one.

the only efficient solution -> variable step propeller

As for the palare section, I would use a symmetrical elliptical profile (type bow truster), probably seen the modest speeds, without curvature.

greetings to all

See? It takes "the ones in the profession."
However, in my opinion, you must also consider that a sailboat necessarily has a drift that destroys and slows down the flow that invests the propeller.
and, I throw there a cacchiata consequent to the barrel of today's sun (beach in chief comin - siniscola), try a pump-jet solution? with a proravia stator that optimizes the incoming threads (as said very disturbed), propeller and, outgoing stator? a fluid dynamic analysis would be needed to optimize and evaluate.

 

[Er Presidente]

if the energy of the propeller must be accumulated and used "disjoined", in port, in period of bonaccia or other, ok.
but if the energy must be used directly to push the boat we are not there.
by pure physical law the energy you would get would be only a fraction of that taken away from the boat itself.
It would be like putting a recovery brake, but on a sailboat there is little to recover in "frenated".

 

[Onda]

There are power generators mounted on the boat's stern, with a propeller designed specifically to generate power.
In this way you have the option to choose to use them or not.
their performance is certainly higher than that of a propeller that must be a compromise with propulsion.
this one's website.http://wattandsea.com/I personally prefer a propeller with the folding blades and in case, if I need to pull the hand brake and produce energy.
We do not forget that the sailing power is extremely limited and you risk to brake the boat abundantly to produce some watts of power.
wave

 

[Exatem]

if the energy of the propeller must be accumulated and used "disjoined", in port, in period of bonaccia or other, ok.
but if the energy must be used directly to push the boat we are not there.
by pure physical law the energy you would get would be only a fraction of that taken away from the boat itself.
It would be like putting a recovery brake, but on a sailboat there is little to recover in "frenated".

like kers?:biggrin:
the energy produced must be stored for subsequent uses. but there are wind generators (besides the solar panels with which to cover tugades and tugades) that on a sailboat are very relevant.

There are power generators mounted on the boat's stern, with a propeller designed specifically to generate power.
In this way you have the option to choose to use them or not.
their performance is certainly higher than that of a propeller that must be a compromise with propulsion.
this one's website.http://wattandsea.com/I personally prefer a propeller with the folding blades and in case, if I need to pull the hand brake and produce energy.
We do not forget that the sailing power is extremely limited and you risk to brake the boat abundantly to produce some watts of power.
wave

I quote what is said by wave. In fact, as I said above, a sailboat already has limited speeds for itself and every further famine appendage just makes the situation worse. I remember that in the calculation of the speed of project the item " appendixes" has a not negligible weight.

 

[rbaffigo]

Good morning to all, thank you for the intrvents.
Let's start with the end:
-I would like to thank dragon for the precious advice and ask him, hoping he will forgive my ignorance, what characteristic of the propeller is the curvature?
- can you estimate, how and with what approximation the number of turns that will make the propeller used as turbine according to the applied couple?
- in fact I was thinking of using a symmetrical profile propeller, the only problem is that the commercially symmetrical propellers are typically propellers for regatta boats with swivellable and twist-free blades, I think, therefore, with poor performance.
-I consider the hypothesis to extend the axis line to be able to mount a larger propeller.
- Definitely a propeller that works as a turbine reduces the speed of the boat, but from the documentation I studied online and from some simple physical considerations I think I can say that:
friction increases with the number of turns and with the applied torque up to the stalling conditions of the propeller, then decreases a lot.
a brake applied to a boat near the critical speed works in a field where already a lot of energy is dissipated in a +/- exponential way compared to the speed, therefore it will be enough to slow the boat of a few tenths of kn to "recover" the necessary energy.
made these considerations the "plan" is:
We hope not!
with little wind I will use the low-powered motor to create a little "appearing" (real wind vector symbol and boat speed) to achieve a decent speed.
with medium wind I will start regeneration or block the propeller according to the needs.
with strong wind charged batteries, hot water, ice cream wine, induction stoves.. etc.

 

[rbaffigo]

...and music of course. ...

I hope you are all at the sea, soon

♪

 

[Fulvio Romano]

with little wind I will use the low-powered motor to create a little "appearing"

Are you sure it works? so tighten the boline until it reaches the wind. you have the impression of pushing with the sails, but actually the engine works almost alone.. .
if you do not have an apparent at least 30 degrees the sails refuse more than they push. . .

 

[rbaffigo]

It's obvious that if you're already in bolina and the engine you need to rest. . . .
but with a little motor go to the cross with the sails adjusted of bolina.... .
already widely experienced with endothermic engines and I look forward to doing it with the electric motor (the electric motor consumes according to the couple and not the number of turns... :