Into Unscientific

"."

In classrooms.

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

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

Don't hit him after you say it?

what does this mean?

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

But soon.

Fifth Master Qian wanted to understand Xu Yun's meaning:

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 do it or not."

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

"."

Hearing Fifth Master Qian'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 at the front, causing it to heat up, taking kinetic energy away as heat."

"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."

Hearing Xu Yun's words.

Fifth Master Qian nodded slightly again.

well known.

Gas compression, a common condition in missiles and aircraft, can lead to overloading 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 density of the atmosphere at high altitude is also an environmental factor that cannot be ignored."

"With the density of the atmosphere, the sentence 'the gravitational force is always greater than the centripetal force required for the missile to revolve around the ground' 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, so that it can complete a trajectory similar to [ ], from high to low during the entire flight?"

"The entire steering process is done 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 at the side was stunned 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.

seem

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.

This period of free fall is about more than 10,000 meters. 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.

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

The missile's air rudder and other designs began to take effect.

The propellant burns to generate lateral kinetic energy, which initiates the turning of the missile through side thrust.

Finally, the ultra-wideband proximity fuze started to work, guiding the missile to hit U2.

in the whole process.

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

But on the other hand.

If you want a missile falling at high speed to turn around, 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 that it even far exceeds 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 not launch directly at an oblique 45°?

Of course, it is because the launch at an oblique 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.

Shouldn't have been beaten.

After all, he didn't know whether this plan was 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's the [Space Float] that was on the hot search back then.

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 re-entry, suitable for high-speed re-entry into dense atmosphere.

As for the purpose

Naturally, it is to minimize overloading and heating as much as possible.

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 returned from the moon, it was almost in a free fall vertically toward the earth.

Gravity will continuously accelerate the detector, 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 either.

Any artificial speed change requires manual application of external force.

Wait until you reach your destination.

If you don't want to make a hard landing, 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 increase several times—according to the previous Tsiolkovsky formula, as the speed changes The increase of the rocket mass will increase exponentially.

So this approach is obviously not acceptable.

Finally, after various discussions.

The design team formulated a special regression plan:

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

That is to say, after the reentry 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 returner will be reduced by more than 40%.

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

So just now.

After hearing Fifth Master Qian's inquiry, Xu Yun suddenly came up with 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.

Therefore, if the launch position of the "Zhu Xian Jian" missile can be optimized to a certain extent, its warhead should not be vertically downward, but slightly inclined.

At the same time, if some aerodynamic structural design is carried out on the projectile body, it may be possible 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.

Finally, from the initial [╲] to [→], the whole process does not consume any propellant and maintains a certain degree of kinetic energy.

When approaching U2, the propellant combustion accelerated, and the missile hit the center of 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 doesn't know whether it is difficult in missile design.

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

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

But now it seems

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

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

After about a while.

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

He first looked at Xu Yun with a new look, then walked to Xu Yun's side, and stretched out his hand to press around Xu Yun's Tianling Gai a few times.

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

Xu Yun:

"?????"

A few more seconds passed.

Just now Fifth Master 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:

"Too wild."

See this situation.

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 to reach a supersonic speed after a 30,000-meter missile lands at a certain inclination—after all, the position of U2 is not on the ground, but at 10,000 meters or even close to 20,000 meters." meter height."

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

"So I can only say that there is some 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 still required."

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

As he said.

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

Because it involves the concept of Mach number.

What is the Mach number?

This starts with a concept:

That is, when aircraft fly 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 there is a big difference in the atmospheric temperature between the two.

therefore.

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

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

or to be more precise

The Mach number is not only used to distinguish different types of flow, 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" whose stiffness is inversely proportional to the Mach number.

So when the Mach number is small.

The "spring" is stiffer.

Therefore, 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 enough, air can be considered as an incompressible fluid.

When the Mach number is high.

The "spring" has less stiffness.

Fluctuations in velocity tend to cause localized compression of the "spring", where air is considered a compressible fluid.

The concept is very simple and very easy to understand.

Generally speaking.

Low-velocity fluids whose Mach number is less than 0.3 can be regarded as incompressible fluids.

A fluid with a Mach number 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 does not appear on the surface of the aircraft, but appears in front of the aircraft - the shock wave at this time is also called a detached 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, then 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 you can really come up with this kind of missile, 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, who 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 had three, so the previous allocation plan was 334, and one was actually redundant.

Right now, Fifth Division Qian personally set up the fourth team, so the extra people were naturally pulled in to fight.

According to the division of functions.

Four groups are responsible for four configuration derivations:

Supersonic axisymmetric,

air-breathing propulsion,

Two-dimensional inlet configuration,

as well as

Close cone design of fixed plane shape considering viscosity.

Among them, Qian Wushi and Xu Yun were in charge of the first supersonic axisymmetric, which was also the most difficult direction in the whole process.

But Xu Yun was still happy.

After all, as soon as he was able to partner with Mr. Qian, he was naturally not 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.

Second is

Among the four steps, supersonic axisymmetric is the field closest to fluid mechanics, which involves a lot of fluid mechanics knowledge.

Not to mention how proficient Xu Yun is in this area.

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

Then soon.

Each of the four groups 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 took care of the disabled.

"Comrade Han Li."

After everyone left.

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 wave-guiding body and the internal rotation inlet."

"And the core of this design is the parameter derivation 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 waverider shock surface and the inner cone shock surface that I deduced in the early years."

"The curve CD is a section of the capture line, and 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 various countries in this period.

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.

Nobuoshi Takashima of Neon did this with the close cone method.

Starck in the United Kingdom adopted the variable wedge angle method—this one is actually quite a pity. If the United Kingdom had supported his research more, the United Kingdom might have completed the research and development of the waverider precursor first.

However, Qian Wushi adopted the coupling design of the minimum wave resistance cone-guiding wave-riding body, which is quite bold even in later generations.

no way.

If not find another way.

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

As for the document that Qian Wushi took out, it was not just as simple as it was in the early years.

These documents are all precious materials he sent back from across the sea in advance, and they were called orphans at the time, 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 on the other side of the sea that Fifth Master Qian chose to have such a wave with Xu Yunmang.

Then soon.

Fifth division Qian drew a shock wave shape 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 I wrote down a flow rate formula:

qm=A2kk-1p0ρ0[(pp0)2k-(pp0)k+1k]

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

After writing here.

Master Qian's pen paused slightly, and said to Xu Yun:

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

"Back pressure ratio, or area-velocity 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."

When working in Chengfei in his previous life, Xu Yun once heard a colleague who was engaged in fluids 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.

When calculating the area-velocity relationship, there will be a misunderstanding that can only be known through supercomputing:

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 then calculated the back pressure ratio.

The so-called back pressure ratio.

It 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.

When the external gas reaches the speed of sound and the mass flow rate of the gas reaches the maximum value, 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.

Today, his right hand has not been used, 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 is composed 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 just wait and 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.

At the same time, consider the stable flow of gas, and then assume that the velocity and energy are uniform on the shock section.

Then there is ∫CSv·dA=cA.

Then Xu Yun connected the cross-sectional 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 followed the trend to look at the speaker.

After turning around.

It was discovered that the middle-aged man with a round face called "greater than" in the counting group had come to him 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:

"Greater than comrades, 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, he was a little surprised.

The round-faced middle-aged man didn't speak any more after hearing the words, but also lowered his head and started writing with a pen and paper.

Seeing this, Xu Yun didn't say anything anymore, and continued to think.

About three or four minutes passed.

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

"Comrade Han Li, look at this."

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

Not to mention resentment.

But there's definitely a little bit of impatience.

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 immediately.

Only at 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 variation 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.

While 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."

"You mean me?"

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

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