Chinese Engine Development


free_6ix9ine

Junior Member
Registered Member
If you’re using a secondary turbine to generate electricity to turn a fan, how is that an improvement from directly turning the fan with your primary turbine? You’re taking a hit on both conversion and weight efficiency in that setup.

Weight wise, it balances out. One helicopter turbine can generate enough electricity for 4 electric motors. The electric motors are going to be much lighter than turbofans, while providing the same thrust, since most of energy from turbofans are wasted as heat. There is definitely more room to improve the efficiency of electric motors. So you might be able to get an ultra light weight and efficient engine setup.
 

latenlazy

Colonel
Weight wise, it balances out. One helicopter turbine can generate enough electricity for 4 electric motors. The electric motors are going to be much lighter than turbofans, while providing the same thrust, since most of energy from turbofans are wasted as heat. There is definitely more room to improve the efficiency of electric motors. So you might be able to get an ultra light weight and efficient engine setup.
Are you suggesting a full electric fan driven propulsion? If you are, then I think I misunderstood the proposal. If we’re talking the electric fan generating all the propulsive force the problem is you will probably have to take a pretty hard penalty on top speed.
 

free_6ix9ine

Junior Member
Registered Member
Are you suggesting a full electric fan driven propulsion? If you are, then I think I misunderstood the proposal. If we’re talking the electric fan generating all the propulsive force the problem is you will probably have to take a pretty hard penalty on top speed.

Yes that is what I am proposing. All propulsion is provided by electric fans. China has more experience with electric motors,maybe its possible to increase the power of the electric fans, so max speed can increase? I guess for large transport planes, speed isn't as big of an issue.

I think it's a promising route to explore, maybe even easier than trying to catch up with GE or RR in trying to build ultra efficient turbine engines.
 

SamuraiBlue

Captain
Yes that is what I am proposing. All propulsion is provided by electric fans. China has more experience with electric motors,maybe its possible to increase the power of the electric fans, so max speed can increase? I guess for large transport planes, speed isn't as big of an issue.

I think it's a promising route to explore, maybe even easier than trying to catch up with GE or RR in trying to build ultra efficient turbine engines.
Sorry but this defies basic mechanical principle in which with transfer of energy there will always be a loss, so a turbine rotating a propeller directly, the axle torque will always be stronger than rotation being transferred to various shafts at the same rotating speed.

An interesting idea will be to combine a tubine engine with the electric plasma engine that I posted in the past.
The turbine engine provides electricity and initial combustion and then dump the combustion exhaust into a secondary chamber and then heat up the exhaust with the electric plasma generator to super heat the exhaust resulting to further heat expansion of the exhuast resulting to further thrust.
Basically it should work like an afterburner without dumping more fuel into it.
 
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latenlazy

Colonel
Yes that is what I am proposing. All propulsion is provided by electric fans. China has more experience with electric motors,maybe its possible to increase the power of the electric fans, so max speed can increase? I guess for large transport planes, speed isn't as big of an issue.

I think it's a promising route to explore, maybe even easier than trying to catch up with GE or RR in trying to build ultra efficient turbine engines.
Hitting transonic and supersonic speeds isn’t just a matter of fan power. Due to aerodynamic dependence your fan can only push air up to Mach 1, at best, and as an air breathing reaction mass engine you can only go as fast as how quickly you can propel an airstream. Compressor based designs can get around this by getting extra propulsive velocity via increasing pressure, but on the other hand have much *higher* energy density requirements. The advantage of combustion for compressor based designs is that as you’re trying to drive the airstream beyond transonic speeds heat energy becomes much more efficient than mechanical energy at generating higher pressures and thus driving the velocity of the airstream, and your combustion reaction generates a lot of free heat to use, especially given that you’re basically getting part of that energy via the free stream via oxygen from the atmosphere rather than carrying it. With an all electric design you’d need to find another source of heat to get comparable levels of propulsive velocity, and you can’t get the freebie of extra heat energy provided by your environment.

I think for what it’s worth you don’t need a denser battery or a secondary electric generating turbine to get around the energy density problem for an all electric transonic design. Fuel cells theoretically speaking should be better than both. But if you don’t want a hard cap below transonic speeds you’re going to need to find an efficient way to convert enough electric power to heat that gives you total system efficiency comparable to your combustion driven turbines at transonic and supersonic speeds.
 

Xsizor

Junior Member
Registered Member
Here is an idea that I think China should explore. Instead of building large turbofan engines, why not develop a turbine electric hybrid engine. Electric engines are more efficient and simpler to make than large turbofans. The downside to electric is the battery. So instead of using batteries, why not use a small turbine engine from a helicopter to generate electricity which is used to power the electric engines which drive fan or propeller? Wouldnt this be a much simpler and elegant solution to leapfrog ahead?
You know what's a better idea ? More investments and encouragement of Metallurgical Science and Material Science. Do that, create a domestic self-sustaining ecosystem for Engines/powerplants and the diety of Capitalism shall do the rest for China ( as usual).
 

free_6ix9ine

Junior Member
Registered Member
Hitting transonic and supersonic speeds isn’t just a matter of fan power. Due to aerodynamic dependence your fan can only push air up to Mach 1, at best, and as an air breathing reaction mass engine you can only go as fast as how quickly you can propel an airstream. Compressor based designs can get around this by getting extra propulsive velocity via increasing pressure, but on the other hand have much *higher* energy density requirements. The advantage of combustion for compressor based designs is that as you’re trying to drive the airstream beyond transonic speeds heat energy becomes much more efficient than mechanical energy at generating higher pressures and thus driving the velocity of the airstream, and your combustion reaction generates a lot of free heat to use, especially given that you’re basically getting part of that energy via the free stream via oxygen from the atmosphere rather than carrying it. With an all electric design you’d need to find another source of heat to get comparable levels of propulsive velocity, and you can’t get the freebie of extra heat energy provided by your environment.

I think for what it’s worth you don’t need a denser battery or a secondary electric generating turbine to get around the energy density problem for an all electric transonic design. Fuel cells theoretically speaking should be better than both. But if you don’t want a hard cap below transonic speeds you’re going to need to find an efficient way to convert enough electric power to heat that gives you total system efficiency comparable to your combustion driven turbines at transonic and supersonic speeds.

I agree. for a supersonic or transonic aircraft, fans alone will not work. Maybe an electric plasma jet would be a better approach for a supersonic design:

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The design here also uses a electric fan to drive air thru the plasma engine, so maybe in subsonic flight, the fan will provide all of the propulsion and the plasma jet will act as like an afterburner to achieve transonic or supersonic speeds.
 

free_6ix9ine

Junior Member
Registered Member
You know what's a better idea ? More investments and encouragement of Metallurgical Science and Material Science. Do that, create a domestic self-sustaining ecosystem for Engines/powerplants and the diety of Capitalism shall do the rest for China ( as usual).

Sure, but that's a very risk averse approach. There are leap-frog technologies that can achieve the same results but in an even faster time frame.
 

latenlazy

Colonel
I agree. for a supersonic or transonic aircraft, fans alone will not work. Maybe an electric plasma jet would be a better approach for a supersonic design:

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The design here also uses a electric fan to drive air thru the plasma engine, so maybe in subsonic flight, the fan will provide all of the propulsion and the plasma jet will act as like an afterburner to achieve transonic or supersonic speeds.
That plasma jet design caught my attention to, and it looks like a really promising concept, but the question is always a matter of scalability. The physics that drive an effective proof of concept don’t always scale well when you try to go bigger.
 

Errys

New Member
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2020-07-28 22:32:03

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WS-15 codename Emei.

Speaking of the development of aero engines, the biggest gap between China and the United States was in the research and development model.
The development of aero engines in China is based on aircraft first and then engines. Engine development usually starts after the aircraft model is determined; while in the United States, engines are first developed after aircraft. When developing aircraft, there are already options available. engine.

It can be said that the development model of the United States is in line with the law of aeroengine development. This is because the technical difficulty of aeroengine development is much higher than that of aircraft, and the development time period is much longer than that of aircraft.
Two different R&D models have completely different consequences. Our country often falls into desperation because of the dismantling of aircraft models, and the engine eventually fails. In contrast, the American model is much better. Even if one or two aircraft models are dismantled, the development of engines cannot be stopped. Over time, it will naturally become a powerful engine country. .

Fortunately, the relevant departments of our country have recognized this importance. From the original research and development of aero engines as an important accessory part of aircraft, the importance of aero engines is on par with aircraft, and even It's even higher. To this end, the aero engine department has been independent from the aviation department, and a major special project "Aero Engine and Gas Turbine" has been set up to allocate a huge amount of money for research. Therefore, we have reason to be more optimistic about the future development of my country's aviation engines.

As you all know, WS-15, also called "Emei", is the standard engine of China's stealth fighter J-20. The first public report by official media was in 2017, on the evening of May 25th. The broadcast of CCTV "House of Craftsman" revealed that China's J-20 has been equipped with domestically-made engines, and at the end of the program, it said that from the third-generation mature engine "Taihang" series, it has developed by leaps and bounds to the fifth-generation "Emei" series. "The engine has amazed the world.
CCTV even used the words "wow the world amazed", which shows that the performance of WS-15 is indeed extraordinary.
In fact, the fifth-generation "Emei" engine mentioned in this CCTV report should be the fourth generation, that is, the F119 and F135 engines developed by Pratt & Whitney, both belong to the fourth generation; and the United States before F110, Russian AL-31, and China WS-10 belong to the third generation.

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Regarding the performance of my country's WS-15 and American F119 and F135 engines, military expert Song Xinzhi once drew a table.
From the data in the above table, the afterburner thrust and thrust-to-weight ratio of WS-15 are already at the same level as the mass production model of F119 and the prototype of F135, but it is the same as the improved model of F119 and mass production of F135. There is still a gap.

The ratio of military thrust to afterburner thrust of F119 is about 0.67, the corresponding ratio of F135 is between 0.6-0.64, and the ratio of WS-15 is between 0.57-0.64. It seems to be equipped with WS-15 J- 20 fighters, super patrol capabilities may not be better than F-22 and F-35. In fact, because the J-20 is slender and adopts a duck layout, the aerodynamic characteristics of the transonic resistance are smaller, and the supersonic cruise lift-to-drag ratio is higher. According to the J-20 pilot's feedback, the supersonic flight characteristics of the fighter plane are very good, largely due to the excellent aerodynamic design of the J-20.

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Looking at the bypass ratios of the three aviation engines again, the bypass ratio of F135 is more than double that of F119 and WS-15. This reflects that the F135's outer duct has a larger flow rate and a larger aircraft diameter. The advantage is that it is more fuel-efficient. The disadvantage is that the resistance is greater and the high-altitude thrust drops more. It is not good for achieving supersonic cruise and high maneuverability. From this point of view, F-35 is more suitable for use as an attack aircraft, and is not suitable for air control fighters.

Finally, let's look at the temperature before the turbine. The temperature before the turbine is the first process of the aero engine. An important indicator of the degree of temperature, under the premise of the same design level of the aero-engine turbine and fan, every time the temperature in front of the turbine increases by 100°K, the thrust increases by 15%. It can be seen that the temperature before the turbine has a great relationship with the engine thrust.

The temperature in front of the turbine of F119 aeroengine reached 1977K. It is estimated that the temperature in front of the turbine of F135 aeroengine is at the same level. The temperature before the turbine of the WS-15 is about 1850-1925K, which is close to the level of the two fourth-generation aircraft in the United States, but it is about 50-100K lower. This shows that the fourth-generation American aviation engine has higher thermal efficiency, better heat-resistant materials, and more advanced heat dissipation treatment for thermal components. Although the temperature in front of the turbine of WS-15 has been greatly improved, it still has a gap with the most advanced level, which shows that we will continue to work hard in heat-resistant materials and heat dissipation technology.

However, the F119 also achieved a maximum thrust of 17.4 tons in three stages. At the beginning, its test thrust was only 14.5 tons; in the second stage, it was relaxed to 15.6 tons; and finally it reached 17.4 tons. That is, continuously increase the maximum temperature before the turbine to achieve the purpose of increasing the push. However, due to the later development time of WS15, more mature powder turbine disk and single crystal blade technology are used. Especially the 65,000-ton mold section equipment ranks first in the world. Therefore, its turbine discs and blades can withstand higher temperatures for a long time. The first batch of afterburners with a small amount of off-line has reached 16.2 tons of thrust, exceeding the level of the second batch of F119 engines. Now the fourth batch may be off-line and installed for test flight, and it has been in line with the F119 increased version with about 18 tons of thrust. After the J-20 is installed in batches, it is bound to reach its peak!

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That is to say, the performance of the subsequent batches of WS15 has begun to match that of the F119 in the United States. Besides, with the rapid development of new technologies today, it is entirely possible for us to overtake on corners in the future. So, finally, a new technology in our country, plasma flow control, is listed as one of the 10 cutting-edge aviation technologies by the American Academy of Aeronautics and Astronautics.

According to Li Yinghong, an academician of the Chinese Academy of Sciences, my country has made great progress in the field of plasma flow control. For aero engines, plasma flow control can prevent the most deadly surge in order to prevent the engine from stopping in the air. In fact, plasma flow control has long been developed and applied by some aviation powers, but the main problem is that it can only work at low speeds, not high-speed flow fields. Because it produces too little disturbance to the flow field, it is effective at low speeds. At high speeds, due to the relatively large momentum, the excitation disturbance is submerged and cannot interfere with the flow field.

For this reason, my country has established a special project to solve how plasma flow control works in high-speed flow fields. Finally, a discharge method that produces effective excitation in a high-speed flow field is developed. The basic principle is pulse discharge, which produces strong disturbances in a short period of time, and locally produces strong shock waves, that is, shock wave excitation, but because it is pulsed, the average power consumption is not very large, so the plasma flow is controlled from a low speed. Achieved high speed. Controlling the flow field through flow control can not only expand the stability margin of the engine, but also improve the aerodynamic performance of the aircraft.

Of course, so far, the plasma flow control of aircraft and engines is still in the laboratory stage, which is still far from actual use. However, we have reason to believe that my country will definitely make greater breakthroughs in this field.
Compared with traditional aero engine technology, in the field of plasma flow control, my country and the world's aviation powers started almost at the same time, there is no gap, and we have the advantage of leading the way. My country's future aero engine is worth looking forward to!
 

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