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If the main objective is really zero emissions and not the all important cost, Why not consider the obvious solution which is nuclear propulsion and generation For Merchant ships?? The technology is there and well known, many nuclear powered aircraft carriers, ice breakers, submarines and even cargo ships (Savannah, Otto Han, ect..) have been operating at sea continuously for several decades without any radiologic pollution problems, even when catastrofically lost at sea (like the Thresher and Kursk). Designing, building and operating a nuclear powered container ship, tanker or bulk carrier has already been done long ago and should not be any problems in 2024, no new technology to figure out, its alredy there. Training officers and crew to operate a nuclear powered ship should not be more difficult (and probably easier) than training for navy officers and crews to operate their nuclear aircraft carriers and submarines or for Russian merchant marine officers and crews to operate their nuclear ice breakers, all of which have been no problems since the nineteen fifties and untill now. Of course, the price of a nuclear merchant vessel properly designed, built, manned, operated, certificated, insured, maintained, etc etc… will be very high and such a ship cannot be safely operated by an underqualified crew of 15 people….. However, contrary to the alternative fuels solutions which will anyway still continue to produce at best quite a lot of CO2 and other nasty emissions, a nuclear merchant ship will produce zero CO2, zero sulphur, zero NOX, zero particules, even zero water, in fact nothing at all and will not require any refueling for several years of continuous operation Furthermore, the global cost of nuclear fuel refill for a nuclear ship after several years of operation should be much cheaper than the cost of alternative and expensive fuels and other emission control chemicals and equipment used for the same operating time, no need for shore power while alongside, etc etc., after all, France has produced 70 to 80% of its total consumed power by nuclear plants and without using a drop of expensive fossil or green fuels during the last 40 years with a price almost 4 times lower than Germany In my humble opinion, if we are really serious about a quick and efficient route to zero carbon and emissions in general, nuclear is the only solution for the time being, on shore like on ships, which, contrary to planes and cars, can be easily built with nuclear propulsion and generation. This is the 2 cents of an old retired merchant marine captain and chief engineer
Instead of monitor the ships, simply monitor the petrol companies and force them not sale high sulphur petrol that's all you don't need to monitor the ships, don't let high sulphur petrol in the market that easier for the whole world, unless you just want to fuck our minds 😂
In my view, the onshore power supply for ships in the world's most important ports is paramount to reducing the GHG, mainly for the cruise industry, whose ships spend a considerable time in those ports.
Another as presentation for tanker isolating valve for main fire line is outside of poop deck. But my ship isolation valve located at upper deck inside of accommodation. Is that an NC also sir?
May i ask: as solas require capacity of emergency fire pump is not less than 40% of fire pump and not less than 25 cm3 with 2 hoses. Exp: my ship main fire pump is 140cm3. Emergency fire pump is 48 cm3. So is that an NC?
The e-fuels will most likely have a well-to-wake CO2 factor of close to zero. Given the energy that will be required to set up the infrastructure for these fuels, shouldn't the resultant CO2 emissions be included in these factors?
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Very nice video but to link the tip vortex ventilation to the actual foil ventilation is misleading. The tip vortex is ventilating because somewhere downstream it connects to the free surface allowing the core to ventilate. The ventilation creeps forward as the waterflow speeds up. As the flow speeds up further eventually the pressure drop on the upper surface of the foil is sufficient to trigger ventilation from the surface. It is important to note that the two ventilation mechanisms are separate and occurring at different speed.
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Oh wow, impressive how a ventilated vortex can cause the entire lifting surface to also ventilate. Does the water downstream fall downwards vertically to allow for this?
While giant, natural gas burning ULCVs are a good idea for the near future; I believe modern naval engineers must look to the past if they truly want a "Green" ship of the future. I believe we must utilize the power of the wind along with firm plastic or metal sails long/narrow hulls, auxiliary electric power plants, emergency high efficiency coal burning boilers, and remote control technology. (basically a modern twist on 19th century Clipper technology) From all that I have said up above, what career do you think I pursue? How old do you think I am? I am curious because I think you will guess I am far older than I truly am. Please respond, it would greatly "make my day" if you did. Also, please do not steal my ideas if you read this comment; it would be most inconsiderate if you were to do that for I take pride in my ideas.
From about 25s on you see a "string-like" structure developing from the right side (downstream) towards the tip of the foil. The tip vortex is present all the time, however, it is not visible as such. What you do see is the air which travels in its center from where the vortex hits the free surface (somewhere downstream of the measuring section) towards the tip, i.e. the ventilated tip vortex. As speed increases the ventilation gets closer to the tip.
Thanks for the reply. However, there is a part of your explanation which leaves me still perplexed, when I compare it to what is shown in the video. I hope you don't mind me getting a bit further into this, for the educational purpose? At 0:27-0:28 a tip trail is clearly visible, with the visible part of it starting at some distance behind the trailing edge. If the trail was made of air which ventilates down to the tip, then how do you explain the fact that it is not visibly connected to the foil tip? An air tube would be visible along the whole length of the trail, and it would require a vertical path along the foil as well. IMO, you have possibly mixed the terms "ventilation" and "cavitation" when it comes to the tip-vortex trail. The trail visible at 0:27 is the cavitation, which occures due to the low-pressure in the tip-vortex core. This cavitation tube propagates towards the foil as the speed (or AoA) increases and the pressure in tip area decreases. At some point, the ventilation from the water surface breaks in (0:56) and the cavitation gets substituted by the ventilation. If the foil was completely submerged, with no surface-piercing part, the tip-cavitation tube would still be there, with no ventilation breaking in.
I believe the original video description has it right. The tip vortex does require an air path, as you state, but that air path is coming from downstream. The tip vortex will often migrate toward the free surface (especially if tip vortex cavitation is initially present). If and when the vortex reaches the surface, air is drawn into the vortex core, causing that vortex to aerate/ventilate. That is also why you see the aerated vortex propagate from the downstream direction toward the hydrofoil. A cavitating vortex would begin just downstream of the hydrofoil and move downstream as the velocity - and thus tip vortex strength - increased. Prior to the ventilation formation even at 0:56, the aerated portion of the tip vortex does not reach the tip of the hydrofoil because it the vortex core pressures are not sufficiently depressed immediately downstream of the hydrofoil. It takes a finite distance for the circulation shed from the hydrofoil to coalesce into a single, strong vortex - this is also why the aerated vortex in the video appears larger and less structured as it approaches the hydrofoil. The disperse circulation immediately abaft the trailing edge is not sufficient to reduce local pressures to sub-atmospheric levels. There's a very nice description of this phenomenon in the seminal NASA report by Breslin and Skalak, ca. 1958.
Thanks Casey, your explanation sounds correct. The part which I had missed to notice was (cit.) "that air path is coming from downstream". Yes, an airtube starting to appear from the flow outlet can be observed at 0:23 and that fact explains it all, clearing up my doubts. Also thanks for the report you have cited. I will check it out.
