Posted on 12/18/2023 7:42:23 PM PST by texas booster
You raise a good point.
It was irresponsible then, and similar transactions with Communist China are irresponsible now.
yup, that was just wrong on a couple levels...
don’t remember now if they ever got their peepee wacked or not
From the photo it looks like an unshrouded, eight-bladed prop.
WWG1WGA
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Sadly Capitalists and Free Market players (American or not) don't recognize the power of the Free Market:
"NO! We won't sell that to you until your Nation's Market resembles the Capitalist Free Market System."
That was Reagan's secret weapon that achieved peace without killing, the Economy that could supply ALL the needs of every part of America including the Military.
Communists couldn't match it ever, because they didn't have two ingredients: Freedom and Free Market.
Yup. As was said on the propeller page, the problem with that wasn’t that it enabled the Russians to make quieter props period - they already had the science behind it - but to make them in volume with the required quality control.
Toshiba got pretty roughly handled as a result of that. They lost a *lot* of ground in Japan and are still feeling repercussions today:
https://en.wikipedia.org/wiki/Toshiba%E2%80%93Kongsberg_scandal
Assuming the same power input and equivalent levels of development/manufacture, yes. At higher RPM an open screw is more power efficient than a pumpjet as there’s a sort of “stall” effect in flow at the area between the blade tips and the shroud. It’s why you don’t see the airborne version of the concept on anything bigger than a small drone.
That’s generally not a thing on ships...
It’s worth noting that as commercial computer fluid flow modeling has gotten better and more accessible, there’s also been a huge demand to make quieter props/screws/fans from an area that isn’t so traditional.
Turns out that as electronics have proliferated, people have gotten more and more annoyed by cooling fan noise. Billions of dollars have gone into designing fans that are as close to silent as possible while still moving huge amounts of air. The experience and science behind that is readily available and can directly contribute to quieter in-water screws.
Here’s one example of a silent cooling fan, readily available on the market. Obviously moving air is a little different than moving water, but note the details of the fan - I selected a translucent unit so you could better see the blades. The strakes are not there for style.
https://www.amazon.com/Cougar-CFD12HBG-120mm-Cooling-Green/dp/B00DP5ZCS2?th=1
I was mostly unaware of the fallout of Toshiba's actions.
It appears that, after investigation, the serious punishment was administered by Japan, while the US properly administered trade and financial sanctions.
On noise: I'm certain some noise unnecessarily uses energy, thus an irritating inefficiency. Design of a quieter fan shape should save energy.
Ideally changing air molecule vibration to uni directional pulses and smoothing pulses toward a steady flow. Less noise, more airflow.
From 1980 to 1990 I was working with Automotive Radial Outflow Superchargers, and the impeller designs for them. I see some similar shapes in these cooling fans, even though they are axial.
It's true they are not designed for style, however they are things of beauty.
“That’s generally not a thing on ships...”
Except that it is.
thx, that was my question
laminar flow off the blade hitting the shroud?
lotta vanes on the blades
i guess a Dyson fan is out of the question... 8^)
it was a real mess, Toshiba plant here took sh!t about it and they made vacuum interrupters...
The Dyson fans actually do have a hidden fan in the base.
See “generally” - also, the variable pitch prop has only really been a successful product on extremely large freighters and tankers. But even those have started going to azipods instead.
Other than a few prototypes, the variable pitch screw has never been used on any production class of warship.
It’s related to that, but there’s also massive drag induced.
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