Chapter 1581 Underwater Power

The person who had made an appointment to come to the Torch Laboratory was Du Lin, the director of the Navy Equipment Department, with whom he had collaborated several times before.

When he first received the call, Chang Haonan thought the other party wanted to ask about the strange data obtained from the Canglong.

But Du Lin said that he had some technical questions to ask, and the data were not urgent.

In this case, Chang Haonan naturally couldn't refuse.

After a brief greeting, the two quickly got down to business.

"Academician Chang, you have made a breakthrough in the new type of lithium battery, and our navy has been paying attention to it." Du Lin held the teacup in his hand and let the hot steam hit his face. "This time, I want to understand the safety of this type of battery in...underwater environment. How is the evaluation?"

This question involves too broad a scope. After a little thought, Chang Haonan had to give an answer based on the principle:

"From the perspective of electrochemical principles, this is feasible as long as the battery casing is sufficiently sealed to prevent water vapor from invading."

"The key to actual operation is sealing." He paused, his tone becoming more cautious. "Once water, especially seawater, penetrates into the battery, it can cause electrolyte contamination, active material failure, and a sharp decline in battery performance or even complete destruction. In severe cases, it can directly cause an internal short circuit, instantly releasing huge energy, leading to thermal runaway, fire, or even explosion."

Du Lin did not take any notes, but he obviously listened very carefully.

When he heard the word "sealed", his brows frowned slightly, and then he realized that Chang Haonan might have misunderstood.

So he immediately added: "Academician Chang, we are not going to soak the batteries directly in water, but to power underwater vehicles." He gestured with his hands, "The battery body is installed in the pressure-resistant cabin of the vehicle and works in an air environment. What needs to be paid attention to is the long-term reliability and safety redundancy in this closed cabin environment with large vibrations, temperature and humidity changes."

Chang Haonan suddenly realized: "On the submarine?"

Although the captured Soryu submarine had been sent back, it must have been thoroughly studied before that.

He vaguely remembered that some of the Canglong-class ships in the previous life used lithium batteries instead of Stirling engines. It is very likely that the relevant design was reserved from the beginning and was captured by technicians in the shipbuilding industry.

"Yes." Du Lin nodded, "But it's not a large submarine."

The Chinese Navy has built and equipped nearly ten 09III and 09IIIA attack nuclear submarines with decent technical standards. There is no need to demand the ultimate underwater performance of conventional submarines at the expense of safety.

"You mean... UUV?" Chang Haonan thought for a moment. "In short, the environmental requirements are much clearer. For the cabin environment, as long as the vehicle's sealing and temperature control systems pass the test, the safety of the battery is essentially no different from that used in ground equipment or aircraft."

Having said this, he changed the topic again:

“But UUVs can be charged by a mothership or a mothership, so it seems that there is no need to pursue battery capacity?”

"It's a little bigger than a UUV, but much smaller than a conventional submarine."

Du Lin leaned forward slightly and revealed more specific information:

"The newly formed Special Operations Command wants a small special operations submarine, which is mainly used to transport special operations personnel to perform covert infiltration missions near the coast or in specific waters. Ideally, it should be able to be stuffed into the cargo hold of a large transport aircraft for rapid deployment and delivery, so the most critical thing is that it needs to be small and lightweight."

Chang Haonan instantly understood what the other party meant.

The mini-submarine itself has no damage resistance. If it is hit by a torpedo or depth charge, battery safety will definitely be the least important issue.

However, for the sake of safety, he still reminded:

"The core positioning of our Torch Laboratory is cutting-edge basic research and key technological breakthroughs. We do not have any development plans for lithium battery products themselves, so more specific research and development work still needs to be demonstrated by downstream institutions or enterprises."

"We understand this." Du Lin nodded to show his understanding. "The Navy Equipment Department will coordinate with relevant departments to promote the implementation of the project. As long as Torch can ensure the reliability and supply of core materials and technical packages, we will solve the engineering problems."

His tone was much more relaxed, it seemed that the most important part had been said.

Since the topic has turned to submarines, Chang Haonan couldn't hold back his curiosity and asked:

"Minister Du, did you find anything interesting during the subsequent dismantling and research of the submarine we captured earlier?"

For nearly a year, he has been busy tinkering with the TEM-APT combined equipment and has no extra energy to pay attention to subsequent developments.

"That Stirling engine is basically the same model as ours. At least when it's cold, there's no sign of any subversive difference."

Du Lin showed a hint of "I expected you to ask this" on his face, and replied:

"On the contrary, the design concept and integration of its automated command and control system have provided a lot of inspiration for the design of the command and control system of our new generation of submarines."

He changed the subject and said meaningfully, "Of course, the most valuable thing is that many of its subsystems directly refer to or even copy the original American design... Through the Soryu, we have a more intuitive understanding of the performance boundaries of some non-core but critical subsystems of the Virginia-class."

"This is an unexpected gain." Chang Haonan smiled, "It's a pity that the Canglong still uses a single-axis propeller and does not use a pump-jet propulsion system."

"Who said it wasn't?" Du Lin looked like he was reminiscing. "I have personally talked to Captain Sato Kenji about this several times."

"Ok?"

Chang Haonan became even more curious.

"He said that at the beginning of the design of the Soryu class, there was actually a strong desire to use pump-jet propulsion, and this was also tacitly approved to a certain extent by the US side."

Du Lin replied:

"But at the last minute, the United States was still worried about the leakage of core propulsion technology, so it blocked the transfer, forcing the Japanese to switch back to the traditional single-shaft seven-blade large side-slant propeller... As for the pump-jet technology, they can only turn around and develop it themselves, and it is said that it will not be used until the next generation of submarines."

Chang Haonan smiled even more broadly upon hearing this, and said with a hint of ridicule, "It must be said that the Americans' concerns are very correct..."

The two looked at each other and laughed knowingly.

What leak could be more thorough than sending an almost complete submarine to the opponent for dismantling and research?

From this perspective, they actually hit the mark by accident and reduced the risk of a major technology leak.

The laughter died down, and Du Lin quickly returned to the previous topic: "In fact, when it comes to pump-jet propulsion, our own shipbuilding industry has also been working on it."

Chang Haonan nodded: "I heard something about it during the previous meeting. It was said that users have some concerns?"

"The test results of the current test boats show that the pump-jet has obvious advantages in terms of quietness in the low- and medium-speed cruising section, which is much quieter than the best seven-blade propeller. However," he changed the subject and frowned slightly, "once entering the high-speed sprint section, the efficiency of the pump-jet drops rapidly, and the noise increases sharply, even exceeding that of advanced propellers with the same power."

Chang Haonan was not surprised by this.

This is where the complexity of fluid mechanics and acoustics lies. Pump jets can effectively suppress tip vortex cavitation and thrust pulsation at medium and low speeds through duct rectification and the coordination of rotor/stator blades, significantly reducing noise.

However, at high speeds, the duct itself will generate resistance, the flow field will become more complex, and excessive speed at the tip of the rotor blades will easily induce new cavitation noise.

He nodded: "This is indeed a question that the Navy Equipment Department needs to weigh."

But Du Lin has deeper thoughts.

He leaned forward slightly, looked at Chang Haonan sharply, and asked a more forward-looking question: "Academician Chang, I heard that... Torch Laboratory, or the project you lead, involves research on magnetohydrodynamic propulsion?"

"There are indeed related basic researches being carried out. However, our main directions are plasma magnetohydrodynamics, Hall thruster upgrades serving space relay bases, and energy conversion for future space nuclear reactors, among other aerospace projects."

Chang Haonan was slightly surprised but did not hide it:

"If all goes well, we should be able to see some phased engineering application results within three to five years."