Need assistance with my vertical axis turbine
Hi there there, Getting proper into it I am at present attempting to manufacture and assemble a really small scale vertical axis turbine as a part of a small mission. To provide you an concept, your entire diameter of the setup of blades have to be round 12cm. The central shaft is 1.7cm in dia(have added a picture as reference- https://imgur.com/a/2n2fFMf ) Might you please assist me with just a few issues. At present I’m simply planning on attaching this shaft to a easy DC motor and inserting a voltmeter on the two ends for a studying. I additionally plan on testing the output with compressed air throughout the blade, so increased rpms within the take a look at.
1) Will this give me a end result? Or would the voltmeter right here provide no knowledge? Is so is there one other strategy to measure the values. Mainly i simply want a studying to go off, might be present voltage, or energy. I assumed the voltmeter can be the best.
2) Would a traditional DC motor because the motor within the software be appropriate? Im simply seeking to purchase the primary dc motor w good opinions on Amazon. Is there a specific specification i ought to search for? Or moderately is there a greater kind of motor i ought to search for? Ideally one thing simply obtainable. My instructor instructed me given the small scale of the mission, it would not actually matter, however would like to know your ideas.
3) I am sorry if this can be a very fundamental doubt, however the motors i see on the web to purchase, their enter shafts, are solely 3-5mm in dia. How do I am going about connecting this to my turbine’s Central shaft which is 1.7cm(17mm) in dia? Will a easy shaft coupler work or are there higher choices obtainable?
4) Lastly, I’ve shared the design of the turbine i intend to manufacture. Is three-D printing of such a mannequin tough? Is there higher possibility?
Would actually recognize all the assistance. Thanks guys a lot prematurely.
Comments ( 6 )
You need to attach a load. A voltmeter here will read whatever, as there’s power but no current.
Power = Volts x Amps.
There are no amps, as a voltmeter is a very high resistance, millions of ohms:
Amps = Volts / Resistance
Plug ’em both together and you get
Power = Volts x (Volts/Resistance) = V^(2)/R
Rearrange that in terms of volts and…
V^(2) = P x R
R is massive, so even a little power will get lots and lots of volts. This would cause arcing in the motor and wear it down prematurely. A little resistor is plenty enough to sink that and pull the voltage down.
A normal brushed DC motor will give you a rectified sine wave, so you also need to attach an electrolytic capacitor so you can get reasonable results from simple multimeters. A 16V 47 uF capacitor will be plenty, assuming you attached a little load.
You should also put a little disc capacitor across the motor terminals for reasons I won’t go into here fully, but related to how the motor can cause really high instantaneous voltage spikes by its coils behaving as inductors. This is bad for almost anything nearby.
As long as your CAD drawing is parametric just use a good free slicer app like lychee, or chitubox and 3D printing it shouldn’t be hard. Look into what kind of printing resin or filament you’ll need to use depending on how tough or durable you want the final piece to be.
I think that you’ll want a gear motor. Small motors are made to run at thousands of RPMs, so you’ll want whatever gear ratio can take your estimated turbine speed to ~1000 RPM
You might get more informed answers asking somewhere like r/motors
The one area I feel comfortable answering is how to connect your motor to the shaft of your turbine. I would just use something simple like a rubber band as a belt/pulley. This will save you from having to worry about getting things perfectly centered.
Edit: it looks like there are plenty of videos and how-tos for using LEGO motors as generators. I’m guessing what’s true for them is pretty much the same for other DC motors of comparable specs.
Since you are designing the turbine from scratch, you’ll need to generate a performance map at different turbine tip speed ratios to find your optimum operating point. This Means, you’ll need to test the turbine either at a constant rotational speed while changing the air speed, or keep the air speed constant and change the rotational speed by using a variable load.
You can use a DC motor as a generator along with a variable resistor as your turbine load. You may change the load (resistor value) as your mean of turbine speed/torque control. However, DC motors are usually optimized at much higher speeds than wind turbines, so if you dont use a gearbox, the DC will have lower efficiency, which could reduce the accuracy of the reading.
Since you’ll use air from a compressor, set it far from the turbine so that the airflow is more uniform across the turbine, measure the air speed right in front of the turbine with an anemometer, and use it to calculate you upstream wind power. Change the resistor load to measure the turbine power output at different speeds, ideally, you need a variable resistor sized to accommodate the operating range between no load, to a load high enough to fully brake or slow your turbine down.
> Will this give me a result? Or would the voltmeter here offer no data?
> Would a normal DC motor as the motor in the application be suitable?
You will probably be able to measure a voltage, but it will probably be very small. Small DC motors typically run at roughly 6 volts and around 10,000 RPM, Their free-wheeling voltage is roughly proportional to the RPM, whether they’re operating as motors or generators. So unless you can get that motor spinning *really* fast, you’ll only generate a tiny fraction of a volt.
You are likely to need a gear or pulley system to get the motor spinning fast enough to generate measurable power, but that will add extra friction to your system…
Also I’m not sure your turbine is well designed, this type of turbine relies on a large difference in drag between the downwind and upwind sides, but yours is almost symmetrical. You might need a stronger “cup” shape.
Anyway, good luck!