January 18, 2018
Japanese Soryu Higher Power Snorkel (Intake and Exhaust) Study
"wispywood2344" has drawn and labelled this very useful diagram of the Japan's top of the line Soryu class submarine. The diagram (minus the Stirling AIP) could represent the Japanese entrant "SEA-1000 Japanese submarine (SEA-J)” in the Australia’s Future Submarine competition (which France won in April 2016). A larger version of the diagram is at http://blog.livedoor.jp/wispywood2344/others/Soryu_cutaway.svg.
Anonymous has kindly provided information for the following. One of the key factors in considering Soryu propulsive power (see January 16, 2018 article) comes through taking account of the efficiency of the snorkel (diesel intake and exhaust) system. If resistance against snorkel intake and exhaust is too high, the diesel generation system does not function well, resulting in poor output.
Though the effectiveness of intake and exhaust system has been proven for Japanese submarines equipped with generators of around 4MW (total), the effectiveness of intake and exhaust has not been published for 8MW generators (the power required by Australian Future Submarines).
In this current article there is some discussion of the Japanese entrant "SEA-J" (diagram above) a Soryu enlarged for Australian conditions.
SEA-J highly likely omitted the Stirling AIP (including LOx tanks, sections (9) and (10), 4th compartment) and was lengthened by 6m (from current 84m to 90m). This provided for:
- extra diesel fuel (to increase range from the current Soryu Mark I's limited 6,100nm
range to the 10,000-12,000nm Australia required
- extra batteries (for increased fully submerged range on battery) and
- larger bunks for the on average taller crew. The bunks are already individual for 65 crew
(ie. no uncomfortable "hot bunking").
Omitting the AIP (especially the large, weight shifting, LOx tank, of diminishing utility on Australia's long range missions) is easily understood. But the 6m increase in length is less understandable. SEA-J's extra length may be needed to handle an extra two diesel engines (four in all for the 8MW total power) instead of just two diesels in the existing Soryu Mark I.
MORE POWERFUL SNORKEL SYSTEM
Rearrangements in SEA-J may be new sections 5, 6 and 7 to accommodate the larger, more powerful, diesel driven snorkel sytem. Such a faster working snorkel system would be required for the extra pressure and faster operation of four diesels (totaling 8MW) in SEA-J.
A larger, more powerful snorkel system may also be required in the Soryu Mark II (see Table, for 27SS, laid down in 2015) which may be launced in 2018. Mark II will have more powerful diesels to more quickly charge and technically exploit the new Lithium-ion batteries (LIBs) to be introduced in Mark II.
Faster charging on Mark II will improve its indiscretion ratio (IR). Indiscretion being a submarine's fully surfaced or shallow submerged danger period, when it is snorting. SEA-J could have also benefitted from fast charge LIBs (if Australia had selected SEA-J).
Mainly by Anonymous
Posted by Pete