Chapter 1214: The total temperature of the wind tunnel is not enough?

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

Although many unexpected problems were solved during the development process, as far as the ultimate goal of "weaponization application" is concerned, we certainly cannot pin our hopes on a model that uses cryogenic liquid propellant.

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

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

Several JF series wind tunnels are huge machines with a total length of hundreds of meters and an outlet diameter of several meters. It is impossible for them to be installed directly in a room in the Institute of Mechanics like the previous JF-X scaled wind tunnel.

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

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 which 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 work 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 CJ equation can only solve the design problem of the detonation drive section. It is impossible to directly present the entire wind tunnel on paper.

It is one thing to design it, another to make it work safely.

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

Even though the Institute of Mechanics is at the forefront of the world in the field of ultra-high-speed wind tunnels, we still know very little about wind tunnel operating conditions within this temperature range.

Coupled with the millisecond-level duration of the experiment, the entire project has entered an almost completely unknown area...

……

Capital city, Huairou.

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

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

Jiang Zonglin himself stood beside the wall with a curtain, introducing the specific progress of the wind tunnel research and 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 and the auxiliary detonation section also significantly increases the ultimate load of the wind tunnel. In fact, considering only the detonation driving section, for the experimental gas with the same pressure and velocity in the shock tube, part of the energy of the rear gas can be transferred to the front gas through the unsteady expansion of the shock wave, thereby further increasing the kinetic energy of the front gas."

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

"..."

Academician Yu, who was sitting upright, pondered for a long time before slowly nodding:

"At present, we can achieve a total temperature of 8000K and a flow rate of 6km/s, which is sufficient to meet the application requirements of Academician Chang. As for the shock wave expansion enthalpy increase you mentioned later, the theoretical and engineering research is not yet 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 see that you have already tested several systems including the gas source, heating, vacuum, and decompression. However, 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 veteran academician who returned to work, the entire project team worked in an orderly manner.

Wind tunnels, especially ultra-high-speed wind tunnels, are truly "fun to start, but you'll have to prepare for the crematorium".

It is simply impossible to start the JF-X by just waiting for a while in a large wind tunnel.

Take the gas source system as an example.

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

And after each test, the inflation needs to be repeated.

If you want to perform multiple tests in succession, you will need to let the air compressor cool down for a while in between.

Taking all the steps into account, even if the staff worked in shifts day and night, on average they could only conduct less than three rounds of testing per day.

Therefore, every startup must be done 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 like the size of the JF-X does not allow people to be on site during startup.

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

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

"The air source system reports that the air compressor has been running for 288 minutes, and the air source pressure is 47.93Mpa, which has reached the set range..."

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

"Vacuum system..."

"Ignition system..."

"..."

As waves of reports sounded, the three rows of indicator lights on the screen in front of him changed from red to green one by one, indicating that the starting 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 Zongli, who had been prepared, suddenly turned the key handle, making a "click" sound.

Immediately afterwards...

Of course it was calm.

The working process of the wind tunnel is ignition, detonation, and blowing, which are completed instantly. Moreover, the control room is quite a distance away from the detonation driving section, so it is certainly impossible to be affected by the wind tunnel in normal working condition.

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

Not until the entire operation ended and several pressure-time curves returned to zero did people with sharp ears hear a faint "puff" sound.

The three rows of indicator lights are still green, indicating that there are no abnormalities in all systems involved in this test.

This finally made Jiang Zonglin, who had been somewhat worried about the strength of the cave structure, breathe a sigh of relief:

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

While issuing follow-up instructions, he skillfully selected the working data of the wind tunnel and prepared to organize and export it.

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

Before he could even cry out in pain, he heard Academician Yu's hurried voice behind him:

"and many more!"

Everyone stopped what they were doing instantly and turned to look in the direction of the general command desk.

"The total temperature data at the drive section outlet is incorrect!"

Almost at the same time as Yu Hongru finished speaking, Jiang Zonglin had already seen the total temperature calculation results on the screen.

"7565K..."

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

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

The difference of nearly 10% is obviously difficult to be treated as a simple testing error.

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