That's for gas pumps (compressors). Liquid pumps have all stages the same size because liquids are not compressible. Adding new stages makes no difference in flow rate, but increases the hydraulic head and pump efficiency.
@@stinkywater007I'm no expert in water impellers but I think it may work a little bit better because some of the power gets lost when the stream of water gets some spin. If the second stage rotates in the opposite direction, that will counteract the spin of the water and add some efficiency. But I don't think it is worth the effort because some stationary vanes in-between the stages and after the second stage can do basically the same but the curvature of the vanes need to be optimized for a specific rpm and flow rate to get maximum efficiency.
I'm inclined to say that the cavitation you see is actually just air being sucked in from the loose fit of the shaft. And one more thing, you actually CAN use heat-inserts with resin. Not as good iirc, but doable.
You can see the cavitation forming on the back of the first set of stator blades when he tries to run it in that lake. It gets significantly worse when it hits the nozzle. At this point, it'd probably be far more efficient and have much more thrust if he just removed everything right up to the first impellor and ran it like that.
i find it interesting how software developers make a crap ton of their stuff free. it's very rare that solo devs try to sell their code. but 3d modelers usually sell their plans instead of benefiting the community. i am both a dev and a 3d modeler. i make all my stuff free and accessible.
Most likely because us developers are more often paid well enough, and are enough in demand to not feel the same level of financial insecurities most other people do. The whole open-source ecosystem is a glimpse into what society could look like without financial insecurities.
I'm a programmer, and I think that the distinction is that 3d models are a work of art, where code is human knowledge in computer readable form. I feel it is immoral to restrict any knowledge by requiring payment for it.
@@sycration a functional 3d model that provides a utility (plans for a house, plans for a drone frame, etc etc) are not art. they are the "code" of the end product.
Unbelievable use of 3D printing and commonly available hardware paired with maximum of 5 randomly placed expletives throughout the video to describe mundane phenomena is a recipe for success that I'll always be excited to watch. Bravo!
If you used counter-rotating impellers separated by a larger-diameter shaft to keep the pressure up, along with another larger diameter cone following the second impeller, such that the system maintains higher than ambient pressure until the nozzle, you wouldn't get cavitation.
Hell yeah, yet again another amazing project. I absolutely love seeing your videos and content, and I am inspired by some of your videos to keep up the hard work.
I think this is the first RU-vid video I've watched where I didn't skip the sponsor product. Infact, it's an integral part of the video itself. Very interesting 🤔
You should compare that to the same design with a single stage, one without the second stage, and one with a single impeller thats as long as the two stages together
Buyer be warned, HeyGears printers will ONLY work with their proprietary and expensive resin refills. You cannot use your own resin. I wish sponsors would disclose this.
@@jackass123455 Other than their website actually explicitly says that these cannot use any resin other than their own brand? The fact that it uses their proprietary resin containers, and the machine constantly measures how much it dispenses means it knows how much resin should be in the tray. There's no way they didn't add all that functionality without being able to stop people from using their own resin.
@@jackass123455Most 3D printing resins harden at a specific wavelength of UV light. Their resins are SPECIFICALLY FORMULATED to be unafected at these wavelengths and the printer filters out those same wavelengths. This means your parts won't adhere correctly without extensive print time tuning, you will lose accuracy and precision, and your end product will be garbage. That has no reason beyond trapping an end user in their hostile ecosystem.
You basically built a mini jetski impeller pump. Would recommend getting a small horizontal shaft gas engine, and use a chain or gear drive to get the RPMs up, and you could slap it on a small boat for a homemade jet boat.
You could put a hole on the side wall beside the first propellor so centrifugal force can push water through a tube connected to a heatsink on the motor so the motor doesn’t overheat.
You've really come along way from your frist diy water impeller designs! Its amazing to see how much more powerful these new ones are getting! Love it!
3D printing allows the amateur designer to test concepts and build workable prototypes in plastic and metal in a home garage or small factory before deciding on a patent or full scale production. Opens up a new world of mechanical design and manufacturing. I have a new design for submarine propulsion that uses a similar principle but with some interesting twists. 😎🇦🇺
To mirror polish your pieces you should definitely use GOI paste, which is made of paraffin/wax, an oil (non silicon based) to soften wax and make it more like a paste and finally the polishing agent which is green chrome oxide (is used like a pigment for paint). Historical curiosity, this was invented in soviet union to polish telescope lenses, top quality result assured!👌😉
You want the second impeller spinning either in the opposite direction (more efficiency), or faster than the first impeller (more thrust). Otherwise there is no benefit over a single propeller, and actually a net loss on performance. You need to use a hollow shaft to connect one of the impellors, and an inner shaft running thru the hollow shift, separated by a high speed bearing, that way you can run at two different speeds. You add gear teeth to the hollow shaft, and either connect the inner shaft directly to the motor or its own gear.
If the second impeller is turning at the same rate and same volume as the first impeller, the most you can hope for is that the flow rate stays the same. It’s possible the flow rate is even reduced. Look at the stages of a turbine engine compressor: each subsequent stage is smaller in diameter with more fan blades and the blades themselves are at a greater pitch than the stage before.
I noticed that you have a stator between the two rotors. The stator is good as it helps to straighten the flow for the 2nd stage, but it looks like as if the shape of the stator is reversed. The blunt end of the stator aerofoil should be facing into the water flow, not away.
Usually, the second turbine is smaller and have a steeper pitch than the first, or is the same pitch but spins faster. Then, there is the possibility of injecting air between the turbines to further increase the velocity of the water, and thus, the thrust.
7:30 You could use a screw here. When you will mount a plastic on this metal part, if you have screw it will guarantee your plastic wont break it. We do it on small robot wheels, you snug them in into motor, but to make sure they are tight we screw trough plastic to reach metal part.
6k rpms is plenty for a jet pump. You should consider optimizing the pump with those rpms. Add a wear ring to tighten up those tolerances of the impellers get rid of the air leaks tweak the impeller pitches and intake duct if needed. Thing should rip with some minor improvements.
Volumetric efficiency. It's massive in water jets of this kind. So the leaks around shafts and joints need to be sealed to a high degree of reliability. We see bubbling around the back flange and the shaft will need a positive seal also. Against even an air leak. You produced a really sweet working model, component series here though.
Second impeller could be larger if the cavity before the constriction was larger too. The water would want to slow down due to the increase of volume, but the fan would keep pushing it into the constriction
Water jets are not as efficient as regular propellers. A jet's advantage is that it can run in shallow water. But in deep water, the boat is slower than the same engine/motor and boat with a propeller geared correctly. That is why propellers are predominant.
Hey my guy. To get your parts to be clearer, just hit em with a quick coat of spray lacquer. Gloss is best. Sanding nearly never improves results that much.
7:06 That´s why you´ll aways need some simple metal machining. Like a lathe. With a lathe, you´d have cut threads on an otherwise smooth rod, cause that´s the way such machines are built. One doesn´t use an end-to-end-threaded-rod, when the threads need to be just on a short part of it.
Again, you've got the stator blades in the middle and now in the nozzle at a completely reversed angle. This isn't a pump, it's now trying to be a compressor, which doesn't work with water. You have water leaving the first impeller and slamming into the side of the stator blades, which creates a huge pressure difference on one side and significantly less on the other. This is the source of all the cavitation you can see. This cavitating mix is then hitting the second impeller at an oblique angle, which leaves by slamming again into the stator blades in the nozzle. The water needs to enter and exit as smoothly as possible, any cavitation inside the pump drastically reduces efficiency, in this case it will badly damage the pump over time.
I think you should rethink your design a little. The jet is really just a pump that creates a pressure difference. There are pump designs that create high pressure zones towards the center of the pump I believe. If you use a multi staged pump where each stage is designed to create a targeted increase in pressure perhaps you could create great pressure at sufficient volumes to make it work at lower rpm's. Another idea, what about implementing an outer bypass that goes through a sort of ducted fan and interacts with the high pressure water coming out of the pump, The way the big aircraft jet engines operate. Have you ever heard of Viktor Schauberger? He had some interesting idea's about how water flows in nature. One of his ideas was how to use a fast moving stream of water in the center of rivers to pull river water around bends and minimize erosion on the river banks. Perhaps this concept could be used in a water jet design some how.
Think of a 2 stage pump that you have essentially built, only use jet engine technology or torque converter for an automatic transmission, and the principal of running compound turbocharger system to force air into an engine, jet engines use counter flow to compress the air, heat it up and increase velocity and pressure.
I may not be an engineer but I think you should move the propellers apart so that water can get sucked properly by the second propeller like I'll make a space between them filled with water and maybe it'll boost the maybe I'll increase the performance a bit, idk maybe it works
AWESOME work! I suggest using a mechanical seal like the ones on home bilge pumps / hot tub pumps. Very simple carbon-on-carbon with a spring! That will reduce most of your air leaks & cavitation
You should do geared impellers from bigger impeller to a smaller impeller like turbine jet have. water doesnt compress but the compression will shoot the water faster thats why the end impeller should spin faster. At least thats my theory
It is definitely a nice build but you should do a second one fixing the issues and tuning it to better performance(stuff like leaks and clearances can be fixed in a second print). Most of your viewers would be interested in a 2.0 with a test using maybe a stand up board... If you will do it, try to find a calibrated rod for the shaft to reduce vibrations... Nice work!
Here's an idea for a video why don't you take that water jet and take the part at the very end of the nozzle the little blades coming out not the ones spinning but the little blades that are direction with the very end take the blades on the inside and make them variable pitch kind of like having ailerons and or flaps or rudders or whatever they call them you can make the vertical ones go left and right, That way you could turn not only the physical water jet housing but The actual watter jet itself? That id like to see!
cavitation is a huge energy loss, you might try reducing pipe size each stage to keep water channeled toward impeller. also gears are trying to crush water, thats why they are failing, lubrication is important.
Great build! You need counter rotating props w/ two motors (gears would be weak, noisy, vibration inducing and steal power). Add a pressure sensor in front of the props, a sensor in between the props and a sensor after the props for discharge pressure. You can then tune the maximum output by adjusting the two motors. Perhaps inlet guide vanes (small and thin) to direct the flow for more bite on the prop - Just like in a turbo jet engine. However the exiting vanes are not needed and are detrimental... Great vid!
I suggest making a test stand, water propulsion is famously unstable, and getting a kick at the wrong time could cost you your prototype in the best case scenario.
you have little leak on side it would be good make a gasket and stick in there seal it up from grey housing to clear plastic give it more pressure output i think of one thing that wasnt tested was amp and watt and how many draw to sent it full power if it too much amp there going need be bigger mower to handle it ( was hoping for weekeater engine 47cc have top out 16k rpm )
So I might be stupid for asking this but why don't jetskis use that gear box just scaled up a bit instead of an engine? Is it because that gearbox does produce the torque to move the ski just asking?
You just proved, that contrary to popular belief, water does not lead electricity as your power leads were soaking in the water, but nothing happened. Next time it's maybe wise to lift them out with the rope or something (assuming you do not have third hand).
Jet drives are not faster than propeller drives nor are they more efficient. They are used in rescue boats for safety reasons and to be able to operate in shallow water. In all other aspects, a propeller is much better. Jet drives are used in jet skis again for safety reasons not because they are faster or more efficient. Race boats use propellers. The fastest boat is propeller drive. Propellers also get better fuel efficiency. Jet drives were originally designed for river rescue. as they can operate in shallow water and maneuver better in currents.
but total energy/power of the flow does not change with narrowing the pipe, that comes from by the motor impeller, so finally the screw drive worked, can you change the resin color on the fly, per pixel.
nice project you have there. Thanks to your transparent jet housing, you can clearly see that there is air in the propeller housing. This is very bad for your efficiency of your jet output. make sure your entire water inlet until your exit is water/air closed !!
Have you ever used a transmission with electric motor to change output force of water parameter balance 3d transmission printed gear and housing baring and shafts Rockwell hardness for the application gold mining pump 🤔 for just a example of pump
Oring is rather for static sealing. You need simmerring seal. That's a basic knowledge for 50Hz water pump. Maybe it is better to start with basic projects and do it properly.
