Into Unscientific Chapter 561

  Chapter 561 Really Kneeling

In classrooms.

   Hearing the words that came out of Xu Yun's mouth.

   Fifth Master Qian and the many members of the 'Zhu Xian Sword' team at the scene were all stunned.

   Don't hit him after you say it?

what does this mean?

   Could it be that what Xu Yun wants to say is the kind of "I am not targeting anyone but you are all rubbish"?

   But soon.

  Fifth Master Qian wanted to understand what Xu Yun meant:

   This guy is afraid that the request he made is too outrageous and he will be beaten up

  So he smiled heartily, waved his hand quite generously, and said to Xu Yun:

   "Comrade Han Li, you don't need to be burdened, just say what you think."

  “It doesn't matter if it's colorful black, or if you want to shrink a certain part while zooming in—it's up to our project team to make it work or not.”

   "I asked you to be my assistant, isn't it because you can come up with some unique insights?"

   Hearing Qian Wushi's words.

   Xu Yun, who had intended to express his inner thoughts, no longer hesitated, and said directly:

   "Director Qian, do you still remember the waverider technology we talked about outside?"

   Fifth Master Qian nodded:

"of course I remember."

  Xu Yun used his fingers to make a free fall from top to bottom, and said:

   "According to the original design, after the 'Zhuxianjian' missile falls from an altitude of 30,000 meters, its falling speed will soon approach the speed of sound, and it will always collide with the oncoming air."

   "Air builds up and compresses in front, causing a temperature rise, which converts kinetic energy into heat and carries it away."

   "At the same time, the air pressure difference between the front and back of the missile will generate air resistance, giving the missile a reverse acceleration, which is the so-called overload."

   Heard Xu Yun's words.

   Fifth Master Qian nodded slightly again.

   Well known.

  Gas compression is a common condition in missiles and aircraft, which can lead to overload and heating - friction is a secondary factor.

  The greater the overload of the aircraft.

   It means that the greater the air pressure in front, the more intense the compression, and the stronger the heat generated.

   Then Xu Yun paused and continued to explain:

   "In addition to this, the high-altitude atmospheric density is also an environmental factor that cannot be ignored."

   "With the density of the atmosphere, the sentence 'the gravitational force of the earth is always greater than the centripetal force required for the missile to revolve around the earth' can be realized."

  "Based on the above points, I have an immature idea, that is."

   "Can we design a projectile body, with the cooperation of a certain launch angle, let it complete a trajectory similar to 【】, from high to low during the entire flight?"

   "The entire steering process is completed through the aerodynamic structure, so that we only need to prepare the lateral propellant needed for the final sprint."

   Hearing Xu Yun's words.

   Fifth Master Qian was taken aback for a moment, and the others at the scene also fell silent.

   After a while.

   Fifth Master Qian's chest rose and fell a few times, and the breathing rate of the whole person.

   suddenly hurried up.

   seems

   Have a door?

To know.

  According to the original design of Qian Wushi and others, the missile's falling steps are as follows:

  After leaving the Zhuxian Sword Formation platform, first perform a period of free fall.

  The free fall period is about 10,000 meters. Let's just give a value. For example, from the range of 30,000 meters to 20,000 meters—U2 performs the task of taking pictures at a height of 18,000 meters or even lower.

   Wait until the vertical height difference between the two sides is one or two kilometers.

  The air rudder and other designs of the missile began to take effect.

  Propellant combustion generates lateral kinetic energy, which begins to turn the missile through side thrust.

  Finally, the ultrwideband proximity fuze started to work, guiding the missile to hit U2.

in the whole process.

  The steering of the missile can be approximated as a shape similar to [L].

But on the other hand.

  In order to make a high-speed falling missile turn, the thrust required here is actually very strong.

  The essence of thrust is to consume the propellant in the combustion chamber.

  Turning requires so much propellant, even far exceeding the consumption of straight-line acceleration. (doi: 10.13675/j.cnki.tjjs.2203015)

  But if the aerodynamic structure can be used to allow the missile to complete the steering by itself

  Then this part of the propellant may be omitted.

   In this way.

  The volume of the entire combustion chamber can be shortened by more than half at once!

What?

  You ask why you don't launch directly at an oblique 45°?

  Of course, it is because the launch at an angle of 45° requires the use of propellant to keep the missile in an oblique downward posture. This method consumes even more propellant than the L-type.

  Looking at Fifth Master Qian who was lost in thought.

  Xu Yun on the side shrank his neck slightly.

   Probably won't be beaten.

   After all, he doesn't know whether this plan is feasible.

  The initial inspiration for the plan he mentioned actually came from the technology used in the return of Chang'e-5 in later generations.

   That is the one that was once on the hot search back then [Space Float].

Of course.

  The real name of this floating technique is actually "jumping reentry", which is a very delicate operation.

   This is a special case of semi-ballistic reentry, suitable for high-speed re-entry into dense atmosphere.

   As for the purpose

  Naturally, to minimize overloading and heating.

   A classmate who was Wu Gang in his previous life should know.

  The distance between the earth and the moon is actually very far.

  When the probe returns from the moon, it is almost in a free fall vertically toward the earth.

  Gravity will continuously accelerate the probe, and eventually it will accelerate to a speed of 10.9KM/S.

   This speed is so fast that it is only 300M/S behind the speed of the second universe.

   There is no drag in space, which means you don't have to run the engine during the flight, but you don't have to hit the brakes anywhere.

  Any artificial speed change requires manual application of external force.

   Waiting to fly to the destination.

   If you don't want to land hard, that is, hit it, you have to change the speed and even the orientation.

  For the moon, rockets can be used to forcibly neutralize force when landing.

   After all, it has low gravity and slow speed.

   But for an object with such a strong gravitational force as the earth, this approach will not work.

the reason is simple.

  The amount of speed change that chemical rockets can provide depends mainly on the amount of fuel.

  If you want to increase the speed change, you must increase the fuel.

   But this way.

Regardless of whether the combustion chamber of Chang'e-5 is enough to store fuel, the launch vehicle of Chang'e-5 will be several times larger—according to the previous Tsiolkovsky formula, as the speed change increase, the mass of the rocket will increase exponentially.

   So this approach is obviously not acceptable.

   Finally, after various discussions.

  The design team has formulated a special regression scheme:

  If the position of entering the atmosphere can be accurately controlled within a range called the "re-entry corridor", then the atmospheric density can decelerate the reentry capsule.

   That is, after the return capsule enters the atmosphere for about 60 kilometers, a bow shock wave will be formed at the bottom.

  This shock wave will eject the returner out of the atmosphere again, and then perform a second reentry.

   In this way.

  The speed of the return device will be reduced by more than 40%.

  This principle is actually the embodiment of Mr. Qian's waverider body.

  So just now.

  After hearing the question from Master Qian, Xu Yun suddenly had an idea:

  The initial conditions of the Chang'e-5 returner and the "Zhuxianjian" missile are actually very similar:

   They all fall vertically.

   It's just that one height is higher and the other height is lower.

  So if we can optimize the launch position of the "Zhuxianjian" missile, its warhead will not be vertically downward, but slightly inclined

  At the same time, some aerodynamic structural design on the projectile body may be able to achieve an effect through the shock wave:

   During the falling process, under the guidance of its own structure, the projectile continuously began to shift horizontally.

  In the end, the initial [╲] changed to [→], but the whole process did not consume any propellant and maintained a certain degree of kinetic energy.

   When it gets close to U2, the propellant burns faster, and the missile hits the heart! (Note: This is a plan I came up with from a friend of the Second Artillery Equipment Research Institute. I didn't come up with it myself. I don't have that brain.)

Of course.

   This is just a picture Xu Yun came up with from a layman's perspective. He didn't know whether it was difficult in missile design.

  In case this inspiration is a concept in the field of missile development and colorful black.

  Then Xu Yun is not ready to drink donkey hair soup.

  However, it seems

   It seems that the situation is not as bad as he thought?

  At least Fifth Master Qian didn't look at the broom in the corner.

   It took about a while.

   Fifth Master Qian blinked just now, and turned his eyes back to reality.

  I saw that he first looked at Xu Yun with a new look, then walked to Xu Yun's side, reached out and pressed a few times around Xu Yun's Tianling Gai.

  After finding that it couldn't be opened, he sighed with some regret.

  Xu Yun:

   A few more seconds passed.

   Only then did Fifth Division Qian slowly opened his mouth and said:

   "Comrade Han Li, to tell you the truth, I really want to see how your brain grows."

   "Aerodynamic optimization with shock waves and launch angles is really cool."

   Fifth Master Qian faintly mouthed the word 'Sao'.

   But in the end, he changed to a few more peaceful words:

   "It's too wild."

  See this scenario.

  Xu Yun couldn't help being overjoyed, and tentatively asked Fifth Master Qian:

   "Director Qian, so... my idea is actually feasible?"

  Fifth Master Qian restrained the emotion on his face when he heard the words, pondered for a moment, and said seriously:

   "Comrade Han Li, your idea is very peculiar, but whether it is feasible... can only be said to have a certain probability."

"After all, the common condition for a shock wave is supersonic speed, and it is actually very difficult for a 30,000-meter missile to reach supersonic speed after landing at a certain inclination. After all, U2's position is not on the ground, but at 10,000 meters or even close to 20,000 meters. the height of."

   "Of course, high subsonic speeds can also generate local shock waves, but we don't have any data for this structural curve to refer to."

   "So I can only say that there is a certain feasibility, but whether it can be implemented in the short term."

   "A more detailed calculation of the Mach number and the derivation of the starting structure is also required."

  When it comes to business, Master Qian's expression is very serious.

   Just as he said.

  Xu Yun's idea is very innovative, but it is very difficult to implement it technically.

  Because this involves the concept of Mach number.

  What is the Mach number?

  This is the first thing to mention a concept:

   That is, when the aircraft flies at supersonic speed, their speed often does not change, and what really changes is the sound speed of the air.

  This is because low-altitude flight and high-altitude flight are two completely different concepts, and the atmospheric temperature of the two is very different.

therefore.

  The same speed may be supersonic at high altitude, but it is often subsonic at low altitude.

   So in order to better differentiate between different types of flows, the real expressive term is the Mach number.

   or more precisely

  The Mach number is not only used to distinguish different types of flows, the most essential function of the Mach number is to reflect the compressed state of the fluid.

   Regarding this point, everyone can understand it like this:

  Think of air as a "spring", and the stiffness of the "spring" is inversely proportional to the Mach number.

   So when the Mach number is small.

   The "spring" is stiffer.

  So the fluctuation caused by the speed will be easily transmitted to all positions of the "spring", and the "spring" will not be compressed.

therefore.

   When the Mach number is small to a certain extent, air can be considered as an incompressible fluid.

  When the Mach number is large.

   The "spring" is less stiff.

  The fluctuations caused by the velocity tend to cause the local compression of the "spring", and the air is considered to be a compressible fluid at this time.

  This concept is very simple and easy to understand.

  Generally speaking.

  Low velocity fluid with Mach number less than 0.3 can be regarded as incompressible fluid.

  The fluid whose Mach number is greater than 0.3 is a compressible fluid.

   And when the Mach number exceeds 1, a shock wave will be generated.

  When the Mach number has exceeded the transonic region.

  The shock wave will not appear on the surface of the aircraft, but in front of the aircraft—the shock wave at this time is also called the detachment shock wave.

   Therefore, in order to ensure that the Jade Sword missile can complete the [] flight under the condition that only the gravitational potential energy provides power, it is necessary to accurately determine the location of the shock wave.

   That is.

   Design of waverider-like structures.

etc!

   Class waverider?

  Think here.

  Fifth Master Qian suddenly realized another thing:

  If this missile was really designed, wouldn't the thing about eating an ax that I told Xu Yun before be the same?

   A few seconds passed.

   Fifth Master Qian gritted his teeth hard.

   That's all.

  If this kind of missile can really be produced, what's the point of eating two axes?

  A real man should eat an axe!

all in all.

   Here we go.

   The discussion on the general direction has come to an end temporarily, and the rest is

  Structural design and calculation.

  So Fifth Master Qian divided the crowd into three groups in the same way as before.

  But it is different from before.

  This time Fifth Master Qian no longer went out to fish with Xu Yun, but formed a fourth team to do calculations.

  Another member of the team is a middle-aged man with the same round face. He looks to be in his early thirties and is a member of the computing team:

   Mentioned earlier.

  The calculation team sent by the base has a total of ten people, but the previous team has three, so the earlier allocation plan was 334, and one is actually redundant.

  Now Fifth Division Qian personally set up the fourth team, so the extra people will naturally be pulled in to fight.

   According to the division of functions.

  Four teams are responsible for four configuration derivations:

  Susonic axisymmetric,

   Air-breathing propulsion,

  Two-dimensional inlet configuration,

as well as

  Compact cone design for fixed planar shape considering viscosity.

  Among them Qian Wushi and Xu Yun are responsible for the first supersonic axisymmetric, which is also the most difficult direction in the whole process.

  But Xu Yun is still happy.

  After all, as soon as he was able to partner with Mr. Qian, he was born not to feel conflicted emotionally, but very excited.

   It is not an exaggeration to say.

   This is a supreme honor, much more honor than being interviewed on TV or winning a certain award.

  Secondly, it is

  Susonic axisymmetric is the field closest to fluid mechanics among the four steps, involving a lot of fluid mechanics knowledge.

   Xu Yun is proficient in this aspect.

  At least you don't need to be possessed by Quincy like before, OvO all the way.

   Then soon.

  The four groups each chose a classroom and started their calculation derivation.

   Among them, Qian Wushi and Xu Yun's group stayed in the original classroom, after all, they take care of the disabled.

   "Comrade Han Li."

   After everyone leaves.

   Fifth Master Qian glanced at the member of the calculation group beside him, pondered for a moment, and said to Xu Yun:

   "Comrade Han Li, do you know anything about supersonic axisymmetric?"

  Xu Yun nodded and said:

   "Well, I have a general understanding. For example, this is one of the three generation methods of the waverider you proposed."

   "The remaining two are or supersonic binary flow fields, and supersonic flow fields flowing through arbitrary three-dimensional configurations."

   "The axisymmetric minimum wave resistance configuration can be obtained through the classical minimum resistance theory, which is the easiest way to generate a waverider."

   Fifth Master Qian nodded in satisfaction.

   Then he drew a relatively simple diagram on the calculation paper and said:

   "Since Comrade Han Li is no stranger to supersonic axisymmetric, let's get straight to the point."

   "The purpose of our group on the technical side is very simple, which is to complete the integrated design of the minimum wave resistance cone waveguide waverider and the internal rotation inlet."

   "And the core of this design is the derivation of the parameters of the cone flow field inside the curved surface."

   Say it.

   Fifth Division Qian took a few more documents from his side and said to Xu Yun

   "Look here, this is the part of the intersection line between the shock surface of the waverider and the shock surface of the inner cone that I deduced in the early years."

  "The curve CD is a section of capture line, usually the intersection point D is located on the central body of the reference flow field of the inward-turning inlet."

   Well known.

   In terms of the integrated design of the precursor inlet, there are many different plans in this period in various countries.

  For example, Levistro uses the streamline tracing method to design the lip of the inlet in the conical flow field to approximately match the two-dimensional inlet configuration.

  Neon's Nobuoshi Takashima did this with the close cone method.

  Britain's Stark uses the variable wedge angle method—this one is actually a pity. If the UK supported his research more, the UK might have completed the research and development of the waverider precursor first.

  While Fifth Master Qian adopted the coupling design of the minimum wave resistance cone-guided wave-rider body, it is quite bold even in later generations.

no way.

   If not find another way.

  Xu Yun's plan has no possibility of landing at all.

  As for the document produced by Qian Wushi, it is not just as simple as in the early years.

  These documents are all precious materials he sent back from across the sea in advance. At that time, they were called orphans, and their preciousness is difficult to describe in words.

   After Jin Beier backstabbed and reported Fifth Division Qian, and Fifth Division Qian and his wife were imprisoned, he could no longer take or mail anything back to China.

Of course.

   It is precisely because of the data that has been done across the sea that Fifth Master Qian chose to have such a wave with Xu Yunmang.

   Then soon.

  Qian Wushi drew a shock wave pattern line on the gap surface, and wrote the intersection point D on the central body of the reference flow field of the inward turning inlet.

   Then wrote down a flow rate formula:

  qm=A2kk-1p0ρ0[(pp0)2k-(pp0)k+1k]

   This is the description of a complete gas under the unitary isentropic steady flow, which was deduced in 1954.

   After writing here.

   Fifth Master Qian paused his pen tip slightly, and said to Xu Yun:

   "Comrade Han Li, what do you think should be calculated next?"

   "Back pressure ratio, or arevelocity relationship?"

  Xu Yun knew that this was not the time for him to be polite, so he immediately expressed his opinion:

   "Director Qian, I personally think the back pressure ratio should be better."

  In his previous life, when he was working at Chengfei, Xu Yun once heard a fluid colleague say something:

  After the shock wave is generated, the entropy will increase, but the stagnation pressure will decrease.

   At the same time.

  The stagnation temperature before and after the shock wave remains unchanged.

   So in this case.

   There will be a misunderstanding in calculating the arevelocity relationship that can only be known through supercalculation:

   Without importing the compressibility factor, the entire formula would be completely useless.

   Therefore, after Fifth Master Qian asked for his opinion, Xu Yun immediately put forward his own opinion—if Fifth Master Qian didn't ask, Xu Yun would take the initiative to speak up.

   And beside Xu Yun.

  Fifth Master Qian also nodded when he heard the words:

   "Just what I want."

   So soon.

   Fifth Master Qian calculated the back pressure ratio.

  The so-called back pressure ratio.

   refers to the ratio of the nozzle outlet static pressure to the upstream stagnation pressure of the nozzle, but in the design scheme it refers to the coupling ratio of the cone flow field and the gas.

  When the cone flow field just reaches the critical condition.

  The external gas reaches the speed of sound and the mass flow rate of the gas reaches the maximum value at the same time. The back pressure ratio at this time is called the maximum back pressure ratio.

  This concept is somewhat similar to the MBPR of later generations, but the interpretation is closer to the downstream.

   Then soon.

  Xu Yun also assessed the state of his right hand.

  His right hand has not been used today, and the load is 0, so he also picked up a pen and paper to help write.

   Well known.

  If the shock is a normal shock, and the shock thickness is not considered, then the shape of the shock control volume will be very symmetrical:

  You make a scissors gesture and point your fingertips down.

   This is the diagram of the shock control volume.

  The CV basic equation of the control volume consists of three continuous equations:

  DΦDt=DDt∫V(r,t)dV=t∫V(r,t)dV+∮S(r,t)undA

  ΔN=(IIσρdτ+IIIσρdτ))t+Δt(IIσρdτ)t

  limΔt→0(Iσρdτ)t+ΔtΔt=CSinσV→dA→=CSinσρVcosαdA (Let's see the layout at the starting point)

   where t is time;

  Fx is the component of the force on the x-axis that controls the fluid in the body;

  v is the fluid velocity vector;

  A is the surface area vector of the control body;

  V is the volume of the control volume.

  Consider the stable flow of gas at the same time, and assume that the velocity and energy are uniform on the shock section.

   Then there is ∫CSv·dA=cA.

   Then Xu Yun connected the cross-section states together and prepared to continue the derivation.

   However, half a minute later.

  Xu Yun suddenly frowned, clicked his tongue, and shook his head slightly:

   "No, if you fit like this, you won't be able to continue the calculation."

   As a result, the voice just fell.

  A voice suddenly came from Xu Yun's ear:

   "Comrade Han Li, why can't we continue to count?"

  Xu Yun was startled for a moment, and looked towards the speaker.

   After turning his head.

  I found that the middle-aged man with a round face called "greater than" in the counting group had come to me at some point.

   Seeing this, Xu Yun glanced at Fifth Master Qian who was counting with his head bowed, and explained in a low voice:

   "Larger than Comrade, isn't that obvious?"

   "The temperature after the shock wave is higher than that before the shock wave, and the pressure rises intermittently and sharply. Obviously, the equation of the diffusion section cannot be calculated."

   Say it.

  Xu Yun shook his head, ready to try to think of another method.

  However, to his surprise.

  The round-faced middle-aged man didn't speak anymore after hearing the words, but also lowered his head and took a pen and paper to write.

  Xu Yun didn't say anything when he saw this, and continued to think.

   About three or four minutes passed.

  The middle-aged man suddenly handed the counting paper to Xu Yun, and said:

   "Comrade Han Li, look at this."

  Xu Yun is still in a period of lack of thought at the moment, being interrupted repeatedly, he still has some thoughts in his mind.

   Dislike is out of the question.

   But definitely a little impatient.

  After all, this is a quasi-axiom that has been established in 2023 for later generations. In Xu Yun's view, there is not much need for discussion.

  However, out of respect for the ancestors of this era, Xu Yun decided to help this comrade find out the problem first, and teach him a simple lesson.

  The result is the first time you see the content of the calculation paper.

  Xu Yun's pupils shrank suddenly.

  I saw this moment.

   There is a derivation written on the calculation paper:

  【Known ρd/ρu=(k+1)Ma2u/2+(k1)Ma2u】

  【and y=pd/pu√[2kx2(k1)k+1]^1/2】

  【Synchronize the above two equations to establish the continuity equation, N-S equation, energy equation and gas state equation of compressible viscous gas in two-dimensional cylindrical coordinates】

  【It can be seen from the variant formula that the cross-sectional state will gradually increase in the second half of the diffusion section, and the final formula can be obtained after introducing the influence of the gas boundary layer】

  【∑F→cv=tcvV→ρdB+csV→ρ(V→n→)dA】

   Look at the calculation results in front of you.

  Xu Yun was shaking violently in his heart.

   subconsciously asked a sentence:

   "Comrade Bigger, what's your name?—I'm asking for your full name."

   "Are you talking about me?"

  The round-faced middle-aged man named Da Da adjusted his glasses when he heard the words, and said with a simple smile:

   "My name is Yu Min. Hey, Comrade Han Li, why did you fall down?"

  (end of this chapter)

Chapter end