Regarding the issue of nozzle material, it mainly focuses on the material supply link.
China is a country severely short of copper. More than 95% of domestically imported copper metal is supplied to major arsenals. There are very few copper coins and copper products on the market. The purity of these imported copper metal is about 99%, which cannot reach industrial grade purity. Copper standard.
Industrial-grade pure copper, commonly known as red copper, has a content standard of more than 99.95%, so it has the best thermal conductivity. This high-end copper raw material is one of the national strategic resources. China has no production capacity and relies entirely on foreign imports.
"It is unrealistic and not economically feasible to purchase copper with a purity of over 99.95%. It seems that we must be self-reliant and establish a complete copper production system in the base area, including mining, smelting, and finally electrolytic refining. In this way, we can obtain copper, which is not only oxygen Gun nozzles need to be used, generators, transformers, telephone lines, bullets and shells, etc., all require copper." Yu Hua thought silently and wrote down a solution for the supply of nozzle materials in his notebook.
Electrolysis method, which is currently the most suitable copper production process in the base area, uses blister copper as the anode, pure copper as the cathode, and copper sulfate solution as the electrolyte. The purity can reach 99.99% after electrolysis.
It is easier to solve the problem of material supply. Now we look back and start with the most difficult part.
How to design the nozzle structure to meet the requirements?
"To obtain supersonic airflow, increasing the pressure and speed is the key. The Laval nozzle structure of the rocket engine should be used here. Although a straight structure design similar to a turbofan engine can also obtain supersonic airflow, the technical requirements are very high."
Yu Hua rotated the pencil in his right hand, and memories emerged. His brain analyzed the oxygen blowing furnace technical video materials of Station B that he had browsed and studied. He combined the important knowledge he had learned in the mechanical engineering department and quickly determined the design of the nozzle structure.
Laval nozzle structure, the main structural design of future rocket engine nozzles. The nozzle is divided into two parts. The shape of the first half is from large to small, and shrinks to a narrow throat structure in the middle, similar to a funnel shape, while the second half is rapidly Expanded, also similar to a funnel shape.
From a fluid mechanics perspective, the Laval nozzle is an interesting design.
Generally speaking, the movement of high-pressure pure oxygen in the nozzle follows the principle of 'when the fluid moves in the tube, the flow velocity is large at small cross-sections and small at large cross-sections'. In the first half of the nozzle, the high-pressure pure oxygen continues to accelerate as the nozzle converges and shrinks. , reaching the critical point of airflow speed in the narrow throat area.
At this time, the subsonic airflow cannot continue to increase, and it no longer follows the principle of 'the flow speed is large in small sections and small in large sections'. The situation is exactly the opposite. The phenomenon of 'the larger the cross section, the faster the flow', so in the second half In part, the Laval nozzle will expand rapidly, increasing the airflow cross-sectional area.
This exquisite design caused the speed and pressure of the airflow to surge suddenly, increasing by an order of magnitude from 300 meters per second to 2-3 kilometers per second, which is about Mach 7-8.
The oxygen lance nozzle adopts the Laval nozzle design, which can easily obtain supersonic airflow, and the rocket engine adopts the Laval nozzle design, which obtains unprecedented huge thrust.
In addition, the familiar engine nozzles of ballistic missiles, anti-aircraft missiles, air-to-air missiles, etc. basically adopt the Laval nozzle structure.
Easy to use and practical.
However, since neither rockets nor missiles were born in this era, people have not yet truly realized the value of the Laval nozzle. Since it was patented by the Swede Laval, it has been left at home to gather dust.
Yu Hua had already conceived the shape and structure of the entire Laval nozzle in his mind. He held the pen in his right hand and drew the oxygen lance nozzle based on the Laval nozzle on the new design drawing.
The entire oxygen lance nozzle adopts a porous structure, with a total of three micro-Laval nozzle structures. Subsequently, Yu Hua established a real-time dynamic nozzle mathematical model for analysis, and the analysis results were obtained a few minutes later.
Under the condition that the pressure and flow rate of the high-pressure pure oxygen flow are constant, the supersonic air flow in the three-hole design has been diverted and the speed is just right, which will not damage the bottom lining of the 2t-level converter.
For a single-hole structure nozzle, under the same operating oxygen pressure parameters, the airflow speed can reach 2 kilometers per second, which will cause serious impact on the furnace bottom lining.
"Just use a three-hole nozzle, which is very suitable for a 2t-level experimental converter." After receiving the analysis results, Yu Hua immediately decided to use a three-hole nozzle, and then started the next step of designing the gun body.
Since the oxygen lance needs to work in a converter with extremely high temperatures and heat radiation, in order to prevent the oxygen lance from being damaged by heat, in addition to an oxygen supply pipeline, a cooling and heat dissipation pipeline should also be added.
Air cooling will definitely not work, liquid cooling must be used.
For the design of the gun body, Yu Hua used a three-pronged plan. The central pipe is the main oxygen supply pipe, the second pipe is for the cooling water inlet, and the third outermost pipe is for the cooling water outlet. The gun body and the tail The connection uses flange and sealing rubber ring.
On the design drawings, a three-hole nozzle oxygen lance composed of standard lines and symbols gradually took shape. Yu Hua established a mathematical model while designing, performed calculations and simulations, obtained data, and then made modifications based on these calculated data.
This is Yuhua’s unique scientific research advantage.
Time passed by, and when all the students in Tsinghua Academy finished their morning examination subjects, Yu Hua withdrew from the high-energy-consuming research and development state, put down his pencil, rubbed his slightly swollen temples, and ended today's oxygen gun research and development. Work.
At present, about 50% of the oxygen lance design work has been completed, and the current efficiency is expected to be completed in three days.
"Computational simulation is good, but it consumes too much. I have more than eight hours of efficient study time every day. Using my mind, the computer can only maintain full load for 50 minutes. If there is any magic pill that can make me run 24/7, And as long as it doesn't hurt my body." The golden mathematical symbols in the center of his mind continued to release a cold meaning. The swelling and discomfort in Yu Hua's brain gradually receded. He felt his own condition with his heart and sighed softly.
Unfortunately, this 'magic elixir' does not exist.
"Tomorrow is July 1st, and there are still seven days left before the Marco Polo Bridge Incident. I don't know where those German machine tools are already. I hope they can be transported to Tianjin Guard before Peiping and Tianjin fall. Time is getting tighter."
Yu Hua did not focus on finding any magic elixir, but silently thought about the upcoming Marco Polo Bridge Incident: "Also, I wonder if the prototype unit of Yu's Seven Towers has arrived at the base."
On July 7, the Marco Polo Bridge Incident broke out.
On July 29, Peiping fell.
On July 30, Tianjin fell.
The window period left for Yu Hua in the northern region is only the last thirty days. If the German machine tools and equipment traded have not been shipped before the fall of Ping and Tianjin, then the entire technology replacement plan is likely to abort.
This batch of German machine tools determines the machinery manufacturing industry in the base area, and Yu's seven-tower prototype unit determines the sulfuric acid industry and explosives industry in the base area.
As the Marco Polo Bridge Incident got closer and closer, a sense of oppression from major historical events followed and enveloped Yu Hua's heart.
Yu Hua took a deep breath, suppressed the emotions in his heart, kept a calm mind and a calm mind, put away the oxygen gun drawings on the table, got up and went to the canteen to eat.
When he is stressed, Yu Hua, who is a foodie, likes to relieve stress by eating.
Turn stress into food intake.
The cafeteria was overcrowded, and the students taking the final exams were talking a lot, complaining about how difficult the subject test questions were this morning. Yu Hua came out of the crowd with a full meal and found a seat to sit down.
Today's lunch was very sumptuous, consisting of white flour steamed buns, pickled mustard, porridge, plus a hard-earned oily dish - potato stew. The school specially added a dish to reward students taking final exams.
There were two whole pieces of fat meat as big as thumb caps placed on the dinner plate, trembling slightly, exuding a mind-blowing allure.
To be honest, it is not unreasonable that Yu Hua only eats lean meat before but now only eats fat meat.
The living conditions are really difficult.
The key point is that this is still the standard of food at National Tsinghua University. In many places, you can’t even get food.
When Yu Hua sat down and was about to start cooking, suddenly, a faint fragrance came, and he saw a young girl sitting in front of him.
"Hello, are you Yu Hua's classmate?" the young girl asked Yu Hua.
Yu Hua, who was disturbed, frowned slightly, raised his head and looked at the girl, and suddenly felt familiar: "I am, what can I do for you?"
Isn't this the girl who asked him for directions to the editorial office of the journal last time?
"Hello, my name is Ye Qingyue, and I am the preliminary editor of the Tsinghua Journal editorial department." Ye Qingyue explained with a gentle smile.
