Zhang Heng s literary achievements, what are Zhang Heng s achievements?

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.

In 132 A.D. (the first year of Yangjia), Zhang Heng invented the earliest geodynamic instrument during the appointment of Taishi Ling, which was called the Houfeng geokinetic instrument. According to the "Book of the Later Han Dynasty, the Biography of Zhang Heng" records: the geodynamic instrument is cast with fine copper, with a circular diameter of eight feet, the top cover is protruding, the shape is like a wine bottle, and it is decorated with the image of turtles, birds and beasts in the Seal Wen Mountain.

There are big pillars, and there are eight roads to close, and the machine is closed.

It has eight directions, each with a dragon with a copper bead in its mouth, and a toad corresponding to each dragon. If there is a ** occurrence on either side, the copper beads contained in the dragon's mouth in this direction will fall into the mouth of the toad, so that the direction of the occurrence of ** can be measured. And it has been tested and fitted with what was designed, as God has been, as has not been done since the books have written.

Once a dragon machine, the ground did not move, the scholars of Luoyang blamed the lack of faith, a few days later, the messenger came, and sure enough, it happened in Longxi**, and everyone obeyed its wonder. Since then, the imperial court has ordered historians to record the place where the earth movement took place.

There are two popular versions of the structure of the geodynamic instrument: Wang Zhenduo's model, that is, the "Du Zhu" is a cylinder similar to an inverted wine bottle, and the mechanism that controls the dragon's mouth is around the "Du Zhu". This model has been largely rejected.

Another model was proposed by Feng Rui of the ** Bureau, that is, the "Du Zhu" is a hanging pendulum (see Yuan Hong's "Later Han Dynasty"), there is a small ball below the pendulum, and the ball is located at the intersection of the "m" shaped slideway (that is, the "Jue Pao Guan" mentioned in the "Later Han Shu Zhang Heng Biography"), **, the "Du Zhu" dials the small ball, and the small ball shoots the mechanism that controls the dragon's mouth, so that the dragon's mouth opens.

The world's **frequent, but really able to be observed with instruments**, in foreign countries, is after the 19th century. The wind and ground motion instrument is the ancestor of the world's most advanced instruments. Although its function is limited to the approximate location of the epicenter, it surpasses the development of world science and technology about 1800 years.

In terms of scientific invention and creation, Zhang Heng has made great contributions to Chinese and world culture. The armillary sphere in China, from the middle of the first century B.C., began to develop rapidly. Geng Shouchang of the Western Han Dynasty invented the earliest armillary sphere.

Around 125 AD, Zhang Heng made a complete armillary sphere on the basis of Geng Shouchang, Fu An and Jia Kui, plus the horizon ring and the meridian ring.

Joseph Needham spoke highly of it: "Zhang Heng was the pioneer of the demonstration armillary sphere, and at the same time he successfully used hydraulic power to operate the ring on the armillary sphere (including for observation), and he used a method to combine the utility of demonstration and observation." Since then, the method of making these two armillary spheres has not changed much for hundreds of years."

He also succeeded in creating the world's first water-powered armillary sphere (also known as an armillary sphere). According to the records of the Book of Song and the Astronomical Chronicles, the armillary sphere still existed in the Eastern Jin Dynasty. In 132 A.D., Zhang Heng made a fuss to determine the ** wind and ground motion instrument, which is very scientific and accurate, and is known as "testing things and fitting like a god".

In addition, Zhang Heng also manufactured three-wheeled rotary cars, guide cars, self-flying wood carvings, etc.

Seismograph. The geodynamic instrument is another masterpiece of the Han Dynasty scientist Zhang Heng. In the Eastern Han Dynasty in which Zhang Heng lived, ** was more frequent.

According to the records of the Five Elements of the Book of the Later Han Dynasty, from the fourth year of Emperor He Yongyuan (92 AD) to the fourth year of Emperor Yanguang (125 AD), a total of 26 major ** occurred. ** Districts are sometimes as large as dozens of counties, causing land fissures, landslides, flooding of rivers, and collapse of houses, causing huge losses. Zhang Heng has a lot of personal experience with **.

In order to grasp the national dynamics, after years of research, he finally invented the geodynamic instrument in the first year of Yangjia (132 AD) - the world's first ** instrument.

According to the "Biography of Zhang Heng in the Book of the Later Han Dynasty", the geodynamic instrument is "made of fine copper, with a diameter of eight feet", "shaped like a wine bottle", with a raised round cover, and the appearance of the instrument is engraved with seal inscriptions and figures such as mountains, turtles, birds, and beasts. Inside the instrument, there is a copper "capital column", and there are eight passages next to the column, which become "eight paths". There is a "tooth machine" in the road.

There are eight dragons cast around the outside of the body of the empty Hongkai, with their heads facing down and their tails facing upwards, arranged in eight directions: east, south, west, north, southeast, northeast, southwest and northwest. The faucet is connected to the engine in the internal tunnel, and each faucet has a copper ball in its mouth. Facing the dragon's head, eight toads squatted on the ground, each with their heads raised and their mouths open, ready to take on the copper ball.

When ** occurs in a certain place, the "capital column" inside the geodynamic instrument is tilted, touching the dental machine, making the faucet in the direction of ** open its mouth, spit out the copper ball, and fall into the mouth of the copper toad, causing a loud sound. So people can know the direction in which ** is happening.

On the third day of the second month of the third year of Emperor Yonghe of Hanshun (138 AD), a dragon machine of the geodynamic instrument suddenly started and spit out a copper ball. At that time, the people in the capital did not feel the slightest sign of **, so some people began to talk about it, blaming the ground for not working. A few days later, someone in Longxi (now southeastern Gansu Province) came to report and confirmed that ** had indeed happened there a few days ago, so people began to be extremely convinced of Zhang Heng's superb skills.

Longxi is more than 1,000 miles away from Luoyang, and the geodynamic instrument is correctly marked, indicating that its seismic sensitivity is relatively high.

According to the research of scholars, Zhang Heng had already used the principle of inertia in mechanics at that time, and the "Du Zhu" actually played the role of the inertial pendulum. At the same time, Zhang Heng must have some understanding of the propagation and directionality of the first wave, these achievements were very remarkable at that time, and Europe did not make similar instruments until 1880, more than 1,700 years later than Zhang Heng's invention.