Chapter 1214 The Total Temperature of the Wind Tunnel Is Not Enough?

For the entire hypersonic weapon project, the double-cone air-launched ballistic missile planned by Chang Haonan is only a verification project after all.

Although many unexpected problems were solved during the development process, in terms of the ultimate goal of "weaponization application", we must not pin our hopes on a model that uses cryogenic liquid propellant.

In the long run, the future of hypersonic weapons is still a standard waverider or waverider-like shape, with a scramjet engine as power.

Therefore, the High Temperature Gas Dynamics Laboratory, which is responsible for the development of the JF14 hypersonic wind tunnel, is also working intensively at the same time...

Several JF series wind tunnels are huge monsters with a total length of hundreds of meters and an exit diameter of several meters. It is impossible to install them directly in a room in the Institute of Mechanics like the previous JF-X scale wind tunnel.

Therefore, for the sake of safety and confidentiality, about half a century ago, the hypersonic wind tunnel development team led by Mr. Guo Yonghuai established a wind tunnel base in Huairou, a remote suburb in the north of Beijing, with the support of Marshal Nie.

In the following decades, it gradually developed into the National Key Laboratory of High-Temperature Aerodynamics for Space Flight.

All the ultra-high-speed wind tunnels that have been built are located in this science city.

Of course, this also includes the JF14 that is under construction.

After successfully verifying the correctness of the analytical solution of the two-dimensional Chapman-Jouguet combustion equation about half a year ago, Jiang Zonglin quickly completed the design of a series of wind tunnel auxiliary systems and preliminarily determined the relevant parameters of the shock wave reflection cavity and the auxiliary detonation section.

However, the C-J equation can only solve the design problem of the detonation drive section, and it is impossible to directly present the entire wind tunnel on paper.

Designing is one thing, and being able to work safely is another.

The final design airflow total temperature of JF14 exceeds 8000K, and it reserves the possibility of upgrading to more than 10000K in the future.

Even though the Department of Mechanics has been at the forefront of the world in the field of ultra-high-speed wind tunnels, there is still little knowledge about the wind tunnel working conditions within this temperature range.

Coupled with the test duration of milliseconds, the entire project has entered an almost completely unknown field...

...

Beijing, Huairou.

Jiang Zonglin's design and development team is gathered around a huge wind tunnel control console, and as usual, they start the day's work with a morning meeting.

However, the person sitting in the middle today is Academician Yu Hongru.

Jiang Zonglin himself stands by the wall with a curtain, introducing the specific progress of the wind tunnel development work:

"The working principle of the JF14 wind tunnel is to generate a high-temperature and high-pressure gas source for the nozzle flow through the reflection of the incident shock wave at the end of the driven section. The end reflection of the incident shock wave does increase the pressure and temperature of the experimental gas, but it also brings a large increase in entropy, which brings additional uncertainty to the experimental results."

"In addition, the two-stage reflection of the shock wave reflection cavity plus the auxiliary detonation section also significantly increases the ultimate load of the wind tunnel. In fact, considering only from the perspective of the detonation driving section, for the experimental gas with the same pressure and speed in the shock tube, through the unsteady expansion of the shock wave, part of the energy of the rear gas can be transferred to the front gas, thereby further increasing the kinetic energy of the front gas."

"But under the premise of ensuring the safety of the wind tunnel structure, the current allowable The maximum speed of the experimental airflow is about 6km/s, and the total temperature is 8500K..."

"..."

After listening to this, Academician Yu, who was sitting upright, pondered for a long time before slowly nodding his head:

"At present, the total temperature of 8000K and the flow rate of 6km/s are enough to meet the application needs of Academician Chang. As for the shock wave expansion enthalpy increase you mentioned later, the theoretical and engineering research is not sufficient. The most important thing at present is to verify and test each individual system and the main structure of the wind tunnel separately."

"I saw that you have tested several systems such as gas source, heating, vacuum, and decompression, but before today's full-load test of the detonation drive section, there are still a few details that need to be confirmed..."

Under the command of the old academician who came back, the entire project team worked in an orderly manner.

Wind tunnels, especially ultra-high-speed wind tunnels, are absolutely "starting up is fun, preparing for the crematorium".

It is impossible to start up like JF-X casually in a large wind tunnel.

Take the air source system as an example.

A test lasting only milliseconds or even microseconds requires the air compressor to work continuously for at least 250-300 minutes.

And after each test, it is necessary to repeat the inflation.

If multiple tests are to be carried out continuously, the air compressor equipment needs to be cooled for a period of time in the middle.

All the steps are calculated, even if the staff work in shifts day and night, on average, less than 3 rounds of tests can be carried out every day.

Therefore, every start must be carried out with extreme caution.

It was not until noon that day that the technicians completed various inspections and returned to the well-protected wind tunnel control room-

Even a small wind tunnel of the size of JF-X is not allowed to have people on site when it is started.

Not to mention these behemoths with a total temperature of several thousand K.

Soon, the operator at the first station reported in a deep voice:

"Air source system report, the air compressor has been running for 288 minutes, the air source pressure is 47.93Mpa, and it has reached the set range..."

"Heating system report, preheating time 210 minutes..."

"Vacuum system..."

"Ignition system..."

"..."

As the reports sounded, the three rows of indicator lights on the screen in front of him turned from red to green one by one, indicating that the start-up conditions had been met.

Academician Yu Hongru stood behind his favorite student, stretched out a hand and gently pressed on the former's shoulder, and took a deep breath slowly:

"Ignition!"

The ignition device of JF14 is a key.

After hearing Academician Yu's voice, Jiang Zonglin, who had been ready for a long time, twisted the key handle violently, making a "click".

Then...

Of course it was calm.

The working process of the wind tunnel is ignition, detonation, and blowing are completed instantly. Moreover, the control room is a long distance away from the detonation drive section, and of course it is impossible to be affected by the wind tunnel in normal working state.

Only the many parameters on the display began to jump rapidly.

Until the entire operation state ended and several pressure-time curves returned to zero, people with sharp ears heard a faint "puff" sound.

The three rows of indicator lights were still green, indicating that all systems involved in this test were normal.

This made Jiang Zonglin, who had always been a little worried about the strength of the tunnel structure, finally relieved:

"Attention to all systems, prepare for cooling and decompression..."

While issuing subsequent instructions, he selected the working data of the wind tunnel with ease, preparing to organize and export it.

Just when everyone thought everything was fine, Jiang Zonglin suddenly felt that the hand on his shoulder trembled violently, and then squeezed hard...

Before he could cry out in pain, he heard the slightly hurried voice of Academician Yu behind him:

"Wait!"

Everyone stopped their actions instantly and turned to look in the direction of the general command desk.

"The total temperature data at the exit of the drive section is wrong!"

Almost at the same time as Yu Hongru's voice fell, Jiang Zonglin had already seen the total temperature calculation results on the screen.

"7565K..."

Although from the perspective of word games, this number can barely be called "8000K level".

But everyone knows that the total temperature value determined in this test should be around 8300K.

A difference of nearly 10% is obviously difficult to treat as a simple test error.

For a moment, the atmosphere in the entire control room became tense because of this value...