Chapter 1300: Drag Reduction and Thrust Increase

This sudden shout startled Liu Yongquan and Han Chenfeng, who had already relaxed.

The two turned around almost at the same time.

Since there was an emergency, it was naturally impossible to continue the previous casual chat topic, including the arrangement of dinner mentioned earlier, which had to be put aside for the time being.

"What's the specific situation?"

Liu Yongquan strode quickly back to the control console and looked at the data display terminal of the engine test bench.

Han Chenfeng knew almost nothing about aero engines, but faced with this situation, after hesitating for a while, he chose to follow the other party and returned to the test workshop.

"Mr. Liu, you see, in the first two rounds of testing, we activated the afterburner, and the engine thrust was maintained at a high level. In addition, the thrust fluctuations were quite violent, so we didn't observe it at the first time."

Ma Xiaoyu had already called up the engine thrust curve from the test and introduced it to Liu Yongquan:

"But when we shut down the afterburner and only maintain the maximum speed of the compressor, we can clearly see that the thrust after the working state stabilizes is about 10% higher than the turbofan 3A we usually test, and it is quite stable. I just tried to lower the speed to 80%, and compared with the previous data, it is still about 3% higher..."

Although the engine will enter mass production after being finalized, as a high-value product with small production volume, each aircraft engine needs to undergo ground bench testing before leaving the factory.

Therefore, Ma Xiaoyu is more familiar with the operating parameters of WS-10A than his own.

Although the factory testing environment does not meet the national military standard for "sea level" thrust requirements, the thrust suddenly increased by 3% when the test environment and test methods remained unchanged. This can obviously only be related to the newly installed plasma generating equipment.

Liu Yongquan took out his reading glasses from his pocket, put them on, and looked closely at the computer screen:

“Indeed, the changes are obvious…”

He frowned and thought for a moment:

"Could it be that the probe interfered with the flow field behind the tail nozzle?"

In fact, no matter what is placed behind the tail nozzle, it will not affect the actual thrust of the engine.

However, the thrust data is tested based on sensors installed on the test bench. If the flow field is severely disturbed, the results may be biased.

For example, in an extreme case, if a thrust reverser is placed behind the engine, the test bench will give a higher result due to the secondary impact of the thrust reverse airflow.

However, he denied it as soon as he finished speaking:

"No... It's just a probe. It can't have such a big impact."

For a moment, the entire control room fell silent, with only the scream of the engine coming from the other side of the armored wall.

After a few minutes, Liu Yongquan still had no clue, so he decided to do the experiment first:

"Remove the probe, restart the afterburner, keep it running for a while, and see how the average thrust compares to normal."

"Yes!"

Ma Xiaoyu nodded, then turned around and started the operation.

Soon, the roar of the engine became more obvious to everyone, and the thrust curve displayed on the screen also quickly increased by a level, reaching a position around 13 tons.

The principle of the afterburner is to make full use of the remaining oxygen in the fuel gas and perform a second fuel injection combustion behind the structure of the engine itself. The generated fuel gas does not pass through the turbine structure but is directly output, so the thrust curve fluctuates very violently, and it is indeed difficult to determine where the center of the fluctuation is with the naked eye.

However, the computer can still give relatively representative results through the thrust data recorded over a longer period of time.

If the engine thrust is not less than a certain value 75% of the time after the afterburner is turned on, it is considered to be the ground bench test thrust.

Under the gazes of more than a dozen pairs of eyes, a number finally appeared on the far right side of the rapidly changing curve on the screen.

"13711.6 kilograms of force..."

Ma Xiaoyu read it out slowly.

There was another moment of silence.

"Turn off the afterburner first and adjust the speed to idle."

Liu Yongquan gave the order while pacing back and forth with his head down:

"The factory test thrust of the WS-10A fluctuates slightly depending on the individual unit, but has never exceeded 13300 kgF. That is to say, even after the afterburner is turned on, today's result is still about 3.5% higher..."

If it is an improvement of a new sub-model, then the 4% thrust increase is indeed not very noticeable.

But the key point is that they don't seem to have to pay any extra price for this...

Just when everyone was racking their brains but couldn't think of any possibilities, an unexpected voice sounded from not far behind:

"Old Liu."

It was Han Chenfeng who had left and returned.

He is a complete layman in the field of aeroengines and was just sitting there just to listen to the fun.

As I listened, I thought of a possibility:

"This situation... I think it is most likely caused by the plasma generator!"

Liu Yongquan stopped and looked at Han Chenfeng with some suspicion, but there was no other way at the moment. No matter who it was, they could only try their best.

"But what is the relationship between plasma and engine thrust... Even if there is an impact, it should have a negative impact, right?"

he asked with some confusion.

"No, it's not as simple as you think..."

Han Chenfeng searched around for a while while speaking, and finally pulled a whiteboard from the wall, then removed the several pieces of paper that were fixed on it with a magnet:

"In fact, many basic concepts of plasma are not particularly clear yet. In the case you encountered, it is possible that the fluid dynamic effect of the interference between plasma and shock waves caused the shock wave system inside the engine to weaken and the flow resistance to decrease. According to the most basic principles of mechanics, the same amount of work can be exchanged for a greater gas flow rate, and the resulting thrust will naturally increase."

"Or another possibility... the plasma generates an electrostatic force on the aerodynamic boundary layer on the inner wall of the engine flow channel, thereby reducing the turbulence of the boundary layer and weakening the efficiency of the turbulent vortex system, which also has the same effect of reducing flow resistance..."

"..."

After this explanation, everyone, including Liu Yongquan, looked at each other in confusion.

Invisibility is achieved by using plasma to absorb radar waves. Both the front and back sides fall into the category of electromagnetism, and this principle is easy to understand.

But using plasma to reduce drag…

Perhaps seeing everyone's confusion, Han Chenfeng added:

"From a theoretical point of view, most of the common forces we encounter, such as friction, elastic force, thrust, etc., are essentially a type of electromagnetic force, so..."

"The more specific principle..."

Before Liu Yongquan could ask, the latter raised his hand to interrupt him and replied with a wry smile:

"The mechanism in this regard is still very controversial, with explanations ranging from disturbance theory to energy theory. I can only assure you that this drag reduction phenomenon exists 100%."

Having said this, he paused for a moment, then continued:

"Also, although I don't know how you plan to control the plasma to form a dense shell, this should be a good sign for your research. It shows that the plasma is generated sufficiently and evenly, which is beneficial to subsequent operations to a certain extent."

Liu Yongquan, who was born as an engineer, did not have strong theoretical ability and was not prepared to challenge his shortcomings, so he gave up asking questions and turned to Ma Xiaoyu who was sitting in front of the computer:

"Xiao Ma, please continue to test the plasma distribution in the tail flame jet according to the original plan. I will report this situation to the 611 Institute and Academician Chang. First, let them judge whether there is hope to apply this phenomenon to the field of aircraft design. Secondly, perhaps Academician Chang will have a more accurate understanding of this phenomenon..."