Genius is just the threshold for me!

"Dongdong, why does this engine have a compressor and a turbine?"

Xu Qingling noticed the still-open detonation engine structure inside and suddenly realized something. Pointing to the blades inside, she asked in surprise, "Isn't that detonation combustion?"

Over the past year, Lin Dong has been working on improving the rotary detonation engine every day, and she has become familiar with the relevant concepts of this type of engine.

That is a rotary detonation engine, which does not require the intake fan blades, compressor, turbine and other structures of a turbofan or turbojet engine.

It can operate just like a ramjet engine and a scramjet engine, as long as it has an air intake, combustion chamber, and exhaust tailpipe.

Moreover, it can start and run directly at zero speed on the ground.

However, the rotary detonation engine that Xu Ziming is currently assembling has a distinct blade structure.

"This can improve thermal efficiency."

Lin Dong explained with a smile, "By adding these sets of blades for compression and boosting, the engine's overall efficiency can be increased by another 9 to 10 points, which is more than 16% higher than the same efficiency. Considering the weight increase brought by the blades, it's still worthwhile."

Compared to turbofan, turbojet, ramjet, and scramjet engines that use Brayton cycle isobaric combustion, knock engines use supercharged combustion.

By using detonation shock waves for instantaneous pressurization and release, under the same environment and speed, the combustion efficiency itself exceeds that of isobaric combustion engines by 30% to 40%.

Now, by adding a compressor to further pressurize the air, the overall efficiency will be increased by another 9 to 10 points.

With an overall efficiency that surpasses that of isobaric combustion engines by two-thirds, it is undoubtedly a very cost-effective design.

After all, compared to the multi-stage blades of turbofans and turbojet engines, the rotating detonation engine, being more violent, has only one-third the number of stages of various blades as a typical low-bypass turbofan, so the engine's weight gain is not significant.

"Won't the turbine melt down?"

Xu Qingling asked with some curiosity.

She had seen test videos of detonation engines; in less than a minute, the point where the test stand and the tailpipe flame came into contact would melt.

Although the test stand is made of ordinary steel, the turbine blades are made of high-temperature resistant metal.

However, the turbine is closer to the combustion chamber and is directly exposed to the detonation heat flow of the combustion chamber, thus encountering a more extreme environment.

"It will melt, so its lifespan is only a little over a hundred hours."

Lin Dong looked at the engine that Xu Ziming was constantly assembling in the cleanroom, and said with an expectant smile, "It's only a little over a hundred hours, which is enough for now."

According to current mainstream speculation worldwide, as well as Lin Dong's verification and confirmation, the rotating detonation engine has three operating modes.

One type is a pure knock engine, which can start at zero speed and go all the way up to hypersonic speeds, but its actual efficiency is relatively low below Mach 4.

This type of engine, which is the least difficult to design after the breakthrough in detonation engine technology, is basically just adding an air intake and an exhaust tailpipe to the detonation combustion chamber.

The second approach is to treat the detonation combustion chamber as a super afterburner, designing it at the rear end of the turbine of a turbofan or turbojet engine, and increasing the engine's thrust through a second detonation afterburner.

This is equivalent to adding a super mode, and the design difficulty is average.

The last option is Lin Dong's current plan, which involves replacing the original combustion chamber, improving the intake and turbine, and creating a knock-off combination engine.

The best efficiency can be achieved below Mach 4 by pressurizing the blades.

At speeds above Mach 4, by designing and adjusting the intake geometry, the blades can be made to disappear and reduce aerodynamic drag, transforming the engine back into a pure knock engine while still achieving optimal efficiency.

This engine design is the most advanced, offering the highest overall performance and efficiency, but it is also more complex to design.

However, with the breakthrough in detonation engine technology, such a cycle combination design no longer involves uncharted technological territory. With the help of 624 to test and collect data, Lin Dong completed it in two and a half months.

"Uh-huh."

Xu Qingling, holding Lin Dong's hand, smiled brightly and said, "Given your fickle nature, you could design the next generation engine in just over a hundred hours, before it even breaks down."

Xu Qingling had witnessed Lin Dong's passion for gadgets since he was a child.

From Hot No. 1 to Hot No. 4, and the WZ-8 reconnaissance aircraft, Lin Dong was very excited and interested in them all as soon as they were developed and assembled.

But once you've flown two flights to verify all the technology and ideas and obtained complete flight data, the "Little Sweetie" becomes like an old lady, a collectible stored in the hangar, and it won't fly more than a few times a year thereafter.

of course.

In Lin Dong's own words, this is to reduce the number of flights and the probability of exposure...

"What does it mean to be fickle and easily bored? You can't even form words with that. That's called having no limits."

Lin Dong pinched Xu Qingling's cheek in annoyance, but then laughed and said, "However, the detonation engine is the limit of aircraft engines. The next generation will be the cycle engine, which can travel between air and space."

Cyclic, this is a rocket ramjet combined engine scheme developed by Northwestern Polytechnical University in its "Flying Sky One" project, which was unveiled eight years later.

The initial solution was to combine rocket engines and aircraft engines to address the problem that missile ramjet engines and scramjet engines could not start at zero speed.

Meanwhile, in the Feitian-2 project, by leveraging the dynamic effects of cyclical changes in propulsion, a variable angle-of-attack autonomous flight technology was developed that can change the flight trajectory at any time.

The missile, which originally had a fixed trajectory, was transformed into a missile that moved in a serpentine pattern, thus achieving the effect of being uninterceptable by the weapon.

However, after the Feitian-2 project ended and the Baidi Space Fighter project was launched, this plan was continuously expanded and gradually became the engine route for the space fighter...

After watching for a while, Lin Dong and Xu Qingling sat in the workshop's rest area and took out Xu Ziming's cola, sunflower seeds, and potato chips, eating them while watching variety shows.

Around 6 o'clock, when the sun had reached the top of the western mountain, suddenly, the workshop door was pushed open.

Xu Ziming, Wang Xingguo, and a few others pushed out two hydraulic stabilizer carts and called out to Lin Dong and his companion as soon as they saw them.

"Xiao Dong, Ling Ling, please open the door. We need to go next door for a test drive..."

"it is good."

Lin Dong put down his cola, picked up the sunflower seeds that Xu Qingling had helped him peel, and quickly went over to enter the password to open the door to the engine test workshop next door.

"Uncle Xu."

Lin Dong looked at the two engines on the hydraulic truck and asked curiously, "Is the final assembly okay?"

Xu Ziming saw the half-full cup of sunflower seeds in Lin Dong's disposable cup and immediately understood what was going on. His face darkened as he said, "If there's a problem, why didn't you come in to help?"

"Uh, everyone has their own expertise. I'm not familiar with manufacturing and assembly," Lin Dong said with an embarrassed smile.

"Really? I heard that back then, some people hand-rolled engine turbine blades..."

Xu Ziming made a sarcastic remark, but didn't continue.

They pushed the cart to a room in the testing workshop and used hoisting equipment to lift the engine onto the test stand.

Secure the oil supply pipeline by driving in high-strength bolts with a fixed torque, connect the starter motor, control circuit and collection circuit.

"Go to the control room, don't stay here."

Xu Ziming closed the partition door, said something to Lin Dong and Xu Qingling who had come with him, and led the way to the control room, which was separated by several concrete walls in the distance.

Lin Dong nodded without saying anything.

Upon arriving at the final assembly workshop and the test drive workshop, follow the instructions of the person in charge; this is a safety regulation that every engineer and researcher must abide by.

Otherwise, if something unexpected happens, the terrifying explosion and the thrust of several tons could blow anything out and smash its brains open.

If it were a WS-15 turbofan engine, operating at full power with 18 tons of thrust, the entire building and its foundation would tremble...

woo-

The group went to the next room, and Xu Ziming pressed the test button to start the motor, which in turn caused the blades to rotate, and the entire test platform was instantly whipped up by a whirlwind.

"The blades are operating without any problems."

Xu Ziming looked at the collected data displayed on the screen, then at the footage captured by the camera, and opened the test control program to start the full-process test.

hum-

The intake and exhaust axial fans in the test workshop are turned on via cameras and microphones.

Immediately afterwards, the entire engine shuddered and emitted a cloud of black smoke. The next moment, a blue-yellow exhaust flame mixed with black smoke billowed out.

"Xiao Dong, is it not a blast?"

Lin Weiliang was momentarily stunned when he saw the tail flame and black smoke.

"The combustion chamber temperature hasn't risen yet, the kerosene hasn't cracked, and the detonation hasn't started..." Lin Dong explained from the side.

The cracking and injection of kerosene requires the high temperature of the combustion chamber.

The engine had just started, and according to the design data, it should take about 15 seconds for it to warm up...

Boom! Boom—

Lin Dong had just finished speaking.

The two engines vibrated twice, and the blue and yellow exhaust flames dissipated, replaced by a pure sky-blue exhaust flame, like a beam of light...

"That went so smoothly?"

Wang Xingguo's eyes widened in surprise: "An engine with detonation, and it passed on the first try?"

"Nonsense, do you think Teacher Xiaodong is like you..."

Jiao You, standing to the side, said excitedly, "Whenever Teacher Xiao Dong designs an engine, it always passes smoothly on the first try."

"13 seconds..."

Lin Dong ignored Wang Xingguo and the other man, glanced at the detonation start time, and said thoughtfully, "We could design an extra set of high-power heating wires for the fuel injection system to preheat and crack the kerosene, thus shortening the detonation start time to within 3 seconds..."

Compared to combustion heating and pyrolysis, electric heating is obviously faster.

Although electric heating increases energy consumption, unlike combustion chamber heating which utilizes waste heat, the slight increase in power consumption during startup has little impact.

"Uncle Xu, increase the thrust and measure the thrust-to-weight ratio..."

Lin Dong kept this idea of ​​improvement in mind and looked at Xu Ziming.

Although the test workshop here at Chengdu Aircraft Industry Group only has a subsonic air intake environment created by axial fans, it cannot simulate the ramjet effect during hypersonic flight.

However, the knock engine has the characteristic of self-pressurization, and on the ground, fuel consumption can be disregarded, and subsonic air intake can still achieve 90% of its performance.

Xu Ziming nodded and quickly adjusted the control parameters.

buzzing-

The power of the axial fan simulating air intake is continuously increasing, and the exhaust air inlet is also moving forward, almost ramming into the engine's air intake.

Large quantities of endothermic kerosene are continuously injected into the combustion chamber through pipelines, where it absorbs waste heat and undergoes high-temperature cracking, turning into methane and hydrogen which are then injected out and compressed and ignited by the detonation wave...

Boom!

The sky-blue exhaust flames from the two detonation engines suddenly increased several times over.

The violent engine thrust relentlessly pounded the test stand, causing the dust on the entire stand and the surrounding ground to tremble and vibrate...

"The thrust-to-weight ratio has exceeded 10, surpassing the WS-15 engine..."

Upon seeing this scene, Jiao You, Wang Xingguo, Lin Weiliang, and others immediately looked at the data collected on the large screen next to them. Watching the engine thrust and thrust-to-weight ratio rapidly increase, Jiao You couldn't help but excitedly shout out the numbers.

"Power-to-weight ratio 10.9...12.7...14.5...16.7..."

Clang—

When the thrust-to-weight ratio reaches 16.7, the pure rotary detonation engine mode is switched cyclically.

The rapidly spinning fan blades came down, and the surging air rushed over the front fan blades and directly into the combustion chamber.

boom--

The engine vibrated twice, the exhaust flame flickered twice, and then suddenly increased tenfold.

The thrust-to-weight ratio, which had been hovering below 17, surged to 19 in an instant, along with the detonation, and eventually settled at 20.1...