Chapter 1215 Where Did the Energy Go?

In fact, according to general engineering experience, when a large equipment is tested for the first time and a certain parameter is found to be 10% low, it is a normal situation in the design process.

There should be some allowance left.

Especially for data like total temperature, it is actually better to be on the low side than on the high side.

At least it's safe.

Including several JF series wind tunnels that have been built in the past, they gradually moved closer to the original design values ​​after multiple rounds of design adjustments.

However, JF14 adopted a strict analytical solution to the second-order C-J equation in its design, rather than relying on a combination of numerical calculations and experience as in the past.

Therefore, at least in the two core units of detonation drive and shock wave reflection, the final error should be relatively small.

After looking at each other in disbelief, everyone in the control room focused their attention on Jiang Zonglin and Yu Hongru behind the podium——

After all, only they can make the final decision.

"Look at the airflow expansion data."

Yu Hongru did not make a decision immediately.

As for the wind tunnel test, no matter how urgent it is, it won't take just a few minutes.

Soon, Jiang Zonglin brought up a pressure signal-time curve on the computer screen with a fluctuation amplitude that first weakened and then became strong.

"The center of the fluctuation is 740.3mV, the corresponding airflow speed is 6175m/s, and the duration is about 125μs..."

While reporting several key data on the chart, he relaxed his brows slightly:

"The airflow data are all normal...the steady-state duration is even slightly better than our expectations, and the pressure fluctuations are also very small."

Yu Hongru, who was standing behind him, looked much better and nodded repeatedly:

"Well...it is indeed far ahead of similar expansion wind tunnels in other countries."

Although this statement is entirely a factual judgment, if it were said from Jiang Zonglin's mouth, it would be a bit bragging.

As the other party's teacher, he has no worries in this regard.

The air in the control room, which was almost solidified, relaxed slightly as a result.

However, Jiang Zonglin's expression soon became a little confused:

"In this case, it means that the calculation method given by Academician Chang and the design steps we determined should be no problem, but only the total temperature..."

"..."

He sighed softly as he spoke and opened the notebook beside him, but his movements were a little aimless.

This kind of situation has never been seen once in his nearly thirty years of research career.

Really don't know where to look for a solution.

Yu Hongru, who was more experienced, put his hands behind his back, lowered his head and paced back and forth without saying a word.

Apparently thinking too.

A few minutes later, he stepped out with a snap, then stopped:

"In this way... first check the sensor related to the total temperature to make sure it is not a problem with the measurement process itself."

Although that is said, in order to ensure data reliability, core sensors such as pressure and temperature in the wind tunnel adopt a double backup system.

If the results of the three sets of measurement systems differ too much, the system will directly report an error instead of mechanically giving a meaningless average.

Therefore, Yu Hongru did not expect to solve the problem with this method, but continued:

"If there is no problem with the sensor, after the cooling and pressure relief process is completed, let the technicians go to the site to check the structural condition of the cave. If it is determined that there are no safety hazards, then increase the parameters by 3% for the next test and see What will be the corresponding changes in the total temperature..."

Engineering matters are sometimes unclear.

But problems must be solved.

On the premise of ensuring safety, work must continue according to plan.

Moreover, other data except the total temperature are all normal, and indeed exceed past experience.

Of course, to be on the safe side, he did not directly increase it by 10% in one step.

Instead, I decided to test it out first.

…

Following the order from Academician Yu, the entire project team took action again.

As a forward detonation drive wind tunnel, although the extra shock wave reflection cavity and auxiliary detonation section of JF16 add a lot of difficulty to the design process, they are originally part of the detonation drive section, so in terms of subsequent maintenance and inspection, they are not It's a little less troublesome than some old-timers.

Therefore, everyone quickly completed all the requirements just now.

Wind tunnel structure, all safe!

This conclusion made Jiang Zonglin feel at ease. He raised his wrist and looked at his watch:

"Let comrades take a rest and conduct the second round of testing on time at three o'clock in the afternoon!"

The operation process of the wind tunnel is completely automated and there is no manual work, but it is still not easy to concentrate for a long time.

However, after giving the instruction just now, Jiang Zonglin himself did not go to rest.

Instead, he closed the notebook that was almost at the end and opened it again——

Don’t start reading from the first page.

Instead, he directly found a certain position in the middle...

His mind was in a mess just now, and reading his notes was just a habitual action to relieve stress.

Now that I calmed down, I suddenly realized that I might be able to find some ideas from the solutions to the two-digit C-J equation that I had memorized before...

It's a shame, though.

Although his understanding of the contents of the notes was much deeper than before, he still could not see any clues until the second test was ready that night.

Academician Yu, who was in his eighties, really couldn't hold on any longer and had been helped down to rest a few hours ago.

Therefore, Jiang Zonglin could only shout the command this time.

It was fun to test again.

Hours of preparation, just for less than a second of work.

"ignition!"

While Jiang Zonglin shouted the command, another operator turned the key and started the JF16 wind tunnel for the second time.

Except for a few set parameters, everything is no different from last time.

It even seems a bit monotonous.

Select data, export, process and analyze...

No additional instructions are needed, and the follow-up work can be completed in a few minutes.

But the result...

"The pressure signal at the outlet of the drive section is 745.3mV, the corresponding air flow speed is 6356m/s, and the duration is about 122μs..."

The operator just now reported a string of data quickly.

Jiang Zonglin calculated the result mentally at almost the same time. The airflow speed had indeed increased by about 3% compared to last time.

A moment later, the other party continued to give the number that everyone was most concerned about:

"Total temperature...7657K."

The total airflow temperature is not measured directly, but calculated from many other data.

Therefore, for those who are less experienced, the results will be slightly slower.

"..."

Jiang Zonglin's heart suddenly thumped.

Then he picked up the calculator from the side and pressed it quickly.

His mental arithmetic results were correct:

"The total temperature has increased by about 1% compared to just now..."

Although others could not actually see the numbers on the small LCD screen, Jiang Zonglin turned the calculator 180° and showed the results to everyone.

"The input parameters were increased by 3% in accordance with Academician Yu's request just now. This is absolutely correct."

Operator No. 2, sitting at the other end of the room, sounded determined.

He is responsible for the final verification of set parameters before ignition.

"The calculation accuracy of the total temperature in the wind tunnel can be controlled within plus or minus 25K, which means that as long as the parameters are improved, the total temperature in the wind tunnel and the airflow speed will increase accordingly. There is no problem with the qualitative trend."

Jiang Zonglin stood behind the screen showing the results and slowly analyzed:

"But the total temperature increase is only about one-third of the calculated range..."

"In other words, during this process, part of the energy...disappeared?"