MTL - The Science Fiction World of Xueba-Chapter 497 Where is the problem?

In the hall of the command and control center, Wang Yu, the chief launcher of the 921 rocket, Liu Xuesong, the chief designer of the 921 rocket, Liu Yong, the deputy director of the technical director of 11 institutes of the Sixth Academy of Aerospace, which mainly focuses on the 921 core and hydrogen-oxygen engines, developed the liquid oxygen kerosene engine. Wu Chunmin, director of 11 Xi'an Institutes of the Sixth Aerospace Research Institute, Li Yonghua, who is responsible for the ground test of the engine and the 101 aerospace companies that provide liquid hydrogen fuel, and Gao Junlong, the aerospace professional department of the 54 Institute of CEC, which is developing a ground safety remote control system, are discussing nervously.

Pang Xuelin and Tao Yongchang stood by and listened.

Under normal circumstances, if the engine pre-cooling fails, the arrow body is over-temperature. For this kind of low-temperature rocket using liquid oxygen kerosene and liquid hydrogen liquid oxygen engine as the power, it is not allowed to perform the launch mission at all.

However, the effective launch time of low-temperature rocket fuel is only 24 hours. After considering the launch window, the time left for everyone to discuss is very limited.

Wang Yudao, Commander of the launch: "The news has just been sent from the satellite. The launch window is from 17:30 to 19:00, and it can be postponed to 19:30 at the latest. Now it is 16:40, considering that one hour is reserved before launch. For the launch preparations, we still have about an hour to solve the problem. Old Wu, you have done the kerosene engine and the above circulating pre-cooling system. Tell us about the situation in front of you. "

Wu Chunmin nodded and said: "The data returned by the front sensor shows that after 2.5 hours of circulating pre-cooling, the total liquid consumption of circulating pre-cooling is 547.76kg, but the temperature of the pump casing is 15K higher than we expected. Normal. The temperature of the pump casing is an important parameter to measure the effect of pre-cooling. We usually take the temperature of the pump casing lower than a certain value as a sign of pre-cooling, and use it as the starting condition of the engine. This time we use the core-level engine The improved version of YF100K adopts the natural convection circulation pre-cooling mode. This mode is mainly to lead a section of pipeline in front of the engine main valve and connect it to the storage tank. We call this section of pipeline the return pipe. Pre-cooling starts, The propellant flows from the tank into the delivery pipeline, passes through the front valve of the pump, the pump cavity, enters the return pipe, and then flows through the return valve through the return pipe and returns to the tank. "

Wu Chunmin paused and continued: "In this system, we have no external driving device, and the flow is only driven by the density difference between the propellant in the return pipe and the conveying pipe, so this is called natural convection circulation pre-cooling. The reason is that due to the low temperature characteristics of the propellant, the ambient air forms a relatively high-temperature heat source. After the propellant enters the pipeline, it is heated and vaporized, and the density becomes smaller, resulting in backflow. In order to enhance the difference between the density of the propellant in the return pipe and the delivery pipeline, Make the circulation run smoothly and ensure the sufficient pre-cooling of the pump. Usually, a section of injection is added to the natural circulation pre-cooling. The injection pipe is connected from the return line, and helium is used as the injection gas source. Short-term helium gas injection enhances circulation. "

"Old Wu, is there any solution?"

Liu Xuesong said.

Wu Chunmin said: "I suggest organizing the first-level helium gas distribution table operator to return to the operation position, switch on the D7 blow-off, conduct helium injection for about half an hour, and enhance the circulation to see if the temperature of the pump casing can be lowered."

Wang Yu looked around: "Don't everyone have any opinions?"

Everyone shook their heads.

Wang Yudao: "Okay, first operate according to the old Wu's method, and order the rescue personnel to be in place. If the pre-cooling is still unsuccessful, the position begins to prepare for the termination of the launch process."

"Yes."

Wang Yu's order was quickly issued.

On the large screen directly in front of the command center, began to switch the screen to the scene in the front tower.

The entire command and control hall was quiet, and everyone waited patiently for the news ahead.

Wang Yu, Liu Xuesong, Liu Yong, Tao Yongchang whispered from time to time.

At this time, Pang Xuelin whispered to Wu Chunmin, "Professor Wu, is this sure to lower the temperature of the pump casing?"

Wu Chunmin looked at Pang Xuelin and shook his head with a bitter smile: "Uncertain, the cycle pre-cooling process is very complicated and involves many physical phenomena: the pre-cooling starts, the pipeline system at room temperature forms a high-temperature heat source relative to the low-temperature medium, and the medium enters the pipe After the road is rapidly vaporized, pure liquid, two-phase vapor-liquid two-phase, and pure gas flow will appear along the pipeline. At the same time, the inner wall of the pipe is cooled by the low-temperature fluid, which will release heat and reduce the temperature of the pipe wall. The temperature of the air does not change much, so that there is a temperature gradient between the tube wall and the outside air, and a heat flow is transferred from the outside to the inside. As the pre-cooling progresses, the temperature of the tube wall gradually decreases. The distribution of the fluid state in the pipe also changes continuously. Until a certain moment, the wall temperature no longer decreases, the heat flow introduced from the outside no longer changes, and the fluid state at various points on the pipeline no longer changes, and the pre-cooling will reach stability Here, our most concern is the distribution of various parameters after the system is stabilized, especially the temperature of the pump casing. In the previous experimental process, the circulating pre-cooling system had no problems, and I did not expect a situation before the launch. The key point is that the liquid consumption of circulating pre-cooling is equivalent to our theoretical calculation, but the temperature is higher than 15K. There must be a problem here. If the method of enhancing the circulation by helium injection is still not feasible, then this launch mission can only Cancellation, we can re-launch after we make further improvements to the circulating pre-cooling system ... "

Pang Xuelin thought for a while and said, "Do you have a design plan for a kerosene engine circulating pre-cooling system? Is it convenient for me to see it?"

"Of course convenient!"

Wu Chunmin said with a smile ~ www.novelbuddy.com ~ He beckoned to a staff member and asked him to bring the design manual of YF100K.

Wang Yu and Liu Xuesong also just glanced at them and didn't care too much.

Although Pang Xuelin has a great reputation, most of his achievements are in the fields of mathematics and natural sciences. The highly specialized application engineering fields such as rockets do not expect Pang Xuelin to help.

However, Pang Xuelin didn't care. Through the catalog page of the design manual, he directly found the theoretical calculation part of the circulating pre-cooling system.

The theoretical calculation of the circulating pre-cooling system is mainly divided into two aspects, the first is the calculation of liquid consumption, and the other is the calculation of circulation.

The manual analyzes the natural circulation pre-cooling theoretically through a series of calculations. The calculation content includes pre-cooling liquid consumption and steady-state numerical calculation. From the results of numerical calculations, the natural circulation pre-cooling of the oxygen system of the engine is good, and there is basically no major flaw in the design. Under normal circumstances, such a large leak should not occur near the launch stage.

Pang Xuelin frowned involuntarily.

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