What is the main content of Xue Baochai s entry into Beijing? How many times did Xue Baochai enter J

The Xue family entered Beijing, one was to send his sister to be selected, the second was to visit relatives, and the third was to personally enter the department to write off the old accounts and calculate the new expenses.

Discharge cooling is another type of convection cooling. Unlike regenerative cooling, the coolant used for exhaust cooling absorbs heat to the thrust chamber and is discharged out of the combustion chamber instead of entering the combustion chamber to participate in combustion. Direct drain coolant reduces the thrust chamber specific impulse, so the coolant flow for drain cooling needs to be minimized while only using drain cooling at the outlet section of the nozzle that is relatively less heated.

There is also radiative cooling, in which the heat flow is transferred from the combustion products to the thrust chamber, and then the heat is radiated by the thrust chamber wall to the surrounding space. Radiative cooling is characterized by simplicity and small structural mass. It is mainly used in the extension section of large nozzles and the thrust chamber of small thrust engines using high-temperature resistant materials.

When cooling in the thrust chamber of the tissue, a relatively low temperature liquid or gas protective layer is established on the surface of the thrust chamber wall to reduce the heat flow to the thrust chamber wall, reduce the wall temperature, and achieve cooling. Internal cooling is mainly divided into three methods: internal cooling (shield cooling), membrane cooling and diaphoretic cooling of head tissues. After the internal cooling measures are adopted in the thrust chamber, the mixing ratio near the wall of the combustion chamber is different from the optimal mixing ratio in the central area (in most cases, the near-wall layer rich in fuel is used) due to the need to reduce the temperature of the protective layer, resulting in the uneven distribution of the mixing ratio along the cross-section of the combustion chamber, so that the combustion efficiency is reduced to a certain extent.

Membrane cooling is similar to shield cooling in that it cools the thrust chamber wall by establishing a uniform and stable coolant film or air film protective layer near the inner wall surface, except that the coolant used to establish the protective layer is not injected by the injector, but is supplied through a special cooling belt. The cooling band is generally arranged in a cross-section of the combustion chamber or the convergence section of the nozzle. There can be several cooling bands along the length of the combustion chamber.

In order to improve the stability of the membrane, the coolant often flows through the gaps or small holes in the cooling belts, and when sweating is used, the thrust chamber wall or part of the inner wall is made of porous material with a pore diameter of tens of microns. Porous materials are usually sintered with metal powders or pressed with metal mesh. In this case, the number of pores per unit area is increased by making the micropores in the material as evenly distributed as possible.

The liquid coolant penetrates into the inner wall, creating a protective film that reduces the density of the heat transferred to the wall. When the flow rate of liquid coolant used for sweat cooling is above a certain threshold, a liquid film is formed near the wall of the thrust chamber. When the coolant flow rate is below the critical flow, the inner wall temperature will be higher than the coolant boiling point at the current pressure, and some or all of the coolant will evaporate, forming an air film.

In addition to the above thermal protection, there are other thermal protection methods such as: ablation cooling, thermal insulation cooling, hot melt cooling and composite protection of chamber walls. 3. Thermal protection scheme of high enthalpy gas generator Based on the above methods and the actual situation, the thermal protection method of high enthalpy gas generator is obtained.

The combustion chamber of a high-enthalpy gas generator differs from that of a liquid rocket engine, eliminating the front thrust chamber part, making its structure simpler and more effective. Then, the thermal protection involved is the thermal protection part of the combustion chamber wall. As the fuel enters the combustion chamber, it quickly decomposes and releases large quantities.

Baoyu went to visit Baochai, and the two looked at each other's golden locks and psychic Baoyu. Then Daiyu also came, and as soon as she entered the door, she mocked Baoyu, Baoyu coaxed Daiyu, saying that she would eat at Aunt Xue's place tonight, and during the meal, Daiyu used the snow goose to send a hand stove to sarcastically mock Baoyu.

After the meal, the two of them went back together, Qingwen just pasted Baoyu's three words on the door, Daiyu said: Why are they all so good. Baoyu, who was a little drunk, was angered by Mama Li's successive actions, and the attacker, who pretended to be asleep, quickly got up to calm down the matter.

The next day, Baoyu and Qin Zhong went to school together, bidding farewell to Jia's mother and father, and then to say goodbye to Daiyu's blindness. On Jia Jing's birthday, a banquet was held in Ningguofu, and Rongguofu Xing, Mrs. Wang, Sister Feng, Baoyu, Jia Lian, Jia Qiang, Jia Rui and others all went to pay their respects.

Sister Feng and Yankong Baoyu went to visit the sick Qin family, and on the way back, Sister Feng met Jia Rui, who was deliberately waiting halfway up the mountain.

From the description of Xue Baochai in "Dream of Red Mansions", it can be seen that the image of Xue Baochai created by Cao Xueqin is a typical standard lady in feudal society. The basic characteristics of this image are that she is a loyal believer in feudal etiquette, a conscious executor, and a pathetic martyr. However, this image of a feudal lady with a beard and a branch is complex and colorful.

Xue Baochai's family lived in Jia Mansion for the following reasons:

1, Xue Baochai entered Beijing to be selected as the admission attendant of the princess and county lord;

2, Xue Pan killed someone in order to rob Xiangling and avoid the limelight;

3, the guy in the store in Beijing bullied Xue Pan when he was young, and he didn't do business well, so he went to Beijing to check the accounts by the way;

4. Aunt Xue and Mrs. Wang are sisters, and Mrs. Wang has long written to them to visit their relatives;

Xue Baochai's family lived in Jia Mansion for the following reasons:

1, Xue Baochai entered Beijing to be selected as the admission attendant of the princess and county lord;

2, Xue Pan killed someone in order to rob Xiangling and avoid the limelight;

3, the guy in the store in Beijing bullied Xue Pan when he was young, and he didn't do business well, so he went to Beijing to check the accounts by the way;

4. Aunt Xue and Mrs. Wang are sisters, and Mrs. Wang has long written to them to visit their relatives;

Mainly because he is going to go to the Beijing draft, but if he can't be selected in the draft, he can marry Baoyu.