The military-industrial scientific research system of the academic master

Chapter 1288: Vigorously works miracles

After all, research on rocket boosters is not the focus of the hypersonic weapons project.

Therefore, after assigning follow-up tasks to Lin Chenggang and Li Yabo, Chang Haonan quickly invested in the research and development of the waverider aircraft itself.

Just as several people were sending Lin Chenggang off, the JF14 wind tunnel had just completed the inspection, maintenance and preparation stage after the last aerodynamics, and could start the next round of testing.

In fact, although the operation of large-scale ultra-high-speed wind tunnels is quite cumbersome, under normal circumstances, it only takes a few hours at best between two starts.

The reason why it took almost an entire day this time was because Chang Haonan wanted to conduct a new multi-physics composite study.

Therefore, in addition to the normal preparation work, a series of modifications to the wind tunnel model and model support frame are also required.

Thanks to the JF14 being specially built for the hypersonic weapons project, the relevant hardware equipment has been reserved in advance.

Otherwise, this kind of functional transformation often takes a week or even longer to complete.

When Chang Haonan and the others returned to the wind tunnel control room, they happened to bump into Chen Hong, who was wearing blue and gray overalls:

"Academician Chang, Lao Jiang, I'm about to go to the computing center to find you."

The latter immediately stopped:

"The No. 3 wind tunnel model has been installed and the ionization generating device is ready. The flow field, temperature field and electromagnetic field sensors are tested normally and can be started at any time."

Chang Haonan nodded and quickly walked to a computer in the center of the console.

Generally speaking, in order to allow operators to directly observe the working conditions inside the wind tunnel, conventional wind tunnels will install a series of cameras around the model.

However, due to the exaggerated working pressure and total airflow temperature of ultra-high-speed wind tunnels, there is no need to install optical observation equipment. The status of the working chamber can only be confirmed through cold sensor data and simulation diagrams.

In fact, the overall outline of the No. 3 model used in this test is not essentially different from that of the No. 1 and No. 2 models. They are both principle models of the standard waverider shape and are not the specific design of any hypersonic flight body.

But inside the model is a completely different hollow structure from the previous two, and a liquid pipeline is introduced through the model support frame below.

At the same time, a series of small holes are set at the top of the waverider head to atomize and eject the prepared ionic liquid.

At this time, a small green dot is displayed next to each equipment point on the screen, indicating that the entire set of equipment is normal.

"Get ready to start."

The JF14 wind tunnel has been started nearly a hundred times since it was first launched, and has long passed the initial unstable stage, so the operation of the equipment itself does not require Chang Haonan to pay too much attention.

Following his order, the staff who had already been prepared were in place. Chen Hong himself turned the key and turned on the ignition switch of the detonation drive section.

The hydrogen-oxygen mixture is ignited by an electric spark within a thousandth of a second. After the detonation wave is enhanced by the multiple superpositions of the shock wave reflection cavity and the auxiliary detonation section, a high-temperature and high-pressure working airflow is formed along the Laval The nozzle pours into the working chamber containing the model to be tested.

Almost at the same time that the detonation wave was generated, the nozzle of the aircraft precursor began to spray forward the reverse ion mist after high-pressure ionization. After encountering the airflow with a speed of up to 12 Mach and a total temperature of 8000K, the strong ion mist that was originally close to the bluff body was bow The shock wave pushes away from the object surface, forming the contact surface, jet layer and Mach disk in sequence in the middle position, and generates a large-scale reflow area near the nozzle outlet, blocking the high-temperature airflow that is enough to melt all metal materials on the surface of the wind tunnel model outside…

…

Although JF14 already belongs to the advanced wind tunnel with "ultra-long experimental time", the effective test period corresponding to each start is only about 100 milliseconds.

Therefore, during the entire process, for people in the control room, they can only hear a weak ignition sound, and then instantly see a lot of sensor data on the computer screen.

Soon, a series of test results required for this test were sent from another dedicated sensor data processing station.

"Compared with the No. 2 model that uses hemispherical struts for protection, the peak heat flux density of the No. 3 model at the initial moment dropped to 477.74W/cm^2, a decrease of 57.4%, and the overall wall heat flux density was controlled at 260W. /cm^2 or less…”

Jiang Zonglin held a heat flow density map in his hand and reported to Chang Haonanhui: "It can be seen from the distribution of the temperature field that the low-temperature and low-pressure fluid in the return zone of the flying body's head covers the surface of the bluff body, which provides good thermal protection. The effect, on the other hand, is that the recirculation zone is attached to the head of the bluff body, making its equivalent shape more slender, so the intensity of the bow shock wave generated is weakened, and the pressure and temperature increases after the wave are quite limited."

"In addition, the flow field monitoring results show that due to the influence of the aerodynamic heating of the incoming flow, the pressure distribution on the entire surface of the flight precursor has also changed accordingly. The aerodynamic dome has formed a local high-pressure area at the leading edge, causing the incoming flow to stagnate. The pressure coefficient reaches Cp=1.87, and the overall gas-heat coupling effect reduces the drag coefficient by approximately 4.4%..."

Seeing the result in front of him was not the best, but it was definitely on the right track, Chang Haonan finally breathed a sigh of relief:

"It shows that our multi-physics coupling strategy for hypersonic flight in the atmosphere is correct...at least in the direction. As long as we continue to adjust those dimensionless parameters later, we can further improve the accuracy of simulation calculations... "

As the saying goes, sharpening the knife will never make you chop wood.

First, use a standard waverider to obtain a sufficiently reliable hypersonic flow field calculation method. Although it will take a certain amount of extra time, it saves a lot of trouble in the actual design process later.

"What about the electromagnetic shielding on the surface?"

Chang Haonan asked again.

"The current sensor cannot directly test the thickness of the plasma sheath on the model surface, but through the electromagnetic wave transmitter installed inside the flying body, it can be obtained that the transmittance of the head in the 8-10Ghz range, and the side wall part at 27 The transmittance in the -35Ghz range has increased, and these are similar to those calculated before, but..."

Speaking of this, Jiang Zonglin's tone showed some hesitation.

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However, he quickly continued:

"But the improvement is not enough, especially the transmittance of the head. Compared with the results of the No. 1 and No. 2 models, it has only improved by 115% and 87% respectively. It is still difficult for the X-band radar to perform as expected. Detection function…”

This is not surprising.

Chang Haonan did not show much frustration:

"The sheath on the head of the waverider is a thin layer that is close to the outer wall. In the vertical direction, the relevant parameters such as electron density and electron collision frequency will change with great gradients, thus forming a structure similar to a discontinuous surface. , causing the reflection effect to be greatly increased, and our ion jet technology mainly weakens the absorption effect of the black barrier, so the effect on the head will indeed be weaker. "

For a missile with a normal layout, the head is where the guidance radar is located, while a satellite communication antenna is installed on the upper side, corresponding to the two most critical guidance methods, both of which are indispensable.

Especially the terminal radar imaging guidance has a decisive impact on the hit accuracy.

"Then...are we going to use other technologies on the front end of the flying body?"

Jiang Zonglin was only responsible for the wind tunnel test, and he did not actually know Chang Haonan's overall design plan for the entire hypersonic missile.

In his opinion, the internal volume of a waverider or waverider-like aircraft is relatively limited, and it is already fully arranged. It is really difficult to insert a complete new system into it.

"That's not necessary."

Chang Haonan took over the test results of electromagnetic wave signal transmission characteristics from the other party and marked several numbers:

"I choose to work hard to achieve miracles."

"ha?"

Jiang Zonglin's head was filled with questions.

Chang Haonan waved his hand directly:

"Increase the intensity of the ion flow used to weaken the plasma sheath by an order of magnitude!"

(End of chapter)