The original design of the 7.5-ton engine to increase the thrust to 12 tons, such a large technical span, Rao is Yang Hui is also a little confused, CFM-56 series can cover from 9 tons to 15 tons, this is because the core machine is awesome, at the beginning of the use of the military push core machine, compared to CG-2000 The core machine used in the push is a congenital positioning.

As a large bypass ratio turbofan engine developed on the basis of the core engine of the central thrust, although a series of more radical technical solutions are used, the performance of this engine is quite good, but this thing really wants to reach the threshold of 12 tons, which is really a little difficult, unless

"So what does Chief Wen mean that we are going to use long-ducted hybrid tail nozzle technology on the basis of CG-2000?"

In fact, as Yang Hui guessed, in the opinion of Chief Wen, in order to achieve the maximum thrust of the CG-2000 series engine to reach the threshold of 12 tons, there is no other choice than to adopt the technology just mentioned.

Finally, it is still going to come to this point, but Yang Hui is not disappointed by this, if it can really be developed to this thrust level for the CG-2000 engine, there is nothing else to ask for, and the development of the entire medium thrust core machine is almost completed.

The so-called long ducted hybrid tail nozzle technology refers to the extension of the outer duct casing through guò until the tail nozzle of the engine, which is very different from the parallel exhaust technology of the outer duct and tail nozzle usually used in high bypass ratio turbofan engines.

Its biggest advantage is that it can mix the air conditioning of the outer duct and the high-temperature gas pass guò blender of the internal channel, which is very different from the traditional high duct ratio turbofan engine cold air and hot gas discharge, which brings many benefits.

Primarily, mixed emissions can significantly increase the efficiency of the fan, even during the climb phase of the aircraft with high power output. It is also in the economic cruising stage in the air, and it has a good efficiency improvement.

Similarly, after adopting this technology, the mixing rate of the internal and external duct airflow can reach more than 70%, which can reduce the exhaust temperature of the tail nozzle and reduce the heat loss of the internal airflow. After the production and blending of the inner and outer duct airflow, the exhaust velocity can also be effectively reduced.

These benefits are too numerous to count, and after combining these benefits, the work efficiency and thrust of the engine can be greatly improved.

After the improvement of work efficiency, the aircraft equipped with this engine can effectively reduce fuel consumption by 2%-3% in flight, and even the noise of the engine can be effectively controlled and reduced by 5%, which can be said to be a very good kind of workmanship.

After using it on Rolls-Royce's RB-211 series, the CFM-34-5C engine also used this technology, and the V-2500 engine was designed to provide enough power to the A321. It's also loaded with this kind of thing.

After doing the math, it is known that engines such as RB-211 using this technology are to be equipped on long-range wide-body airliners, while CFM-56-5C is to be installed on A340 airliners, and V2500 is also used to install A321, a big guy that can carry 200 passengers.

For example, the thrust of the CFM56-3C4 is the largest thrust of the entire CFM-56 family, and its thrust of up to 15 stews is simply the thrust of the entire CFM56 series to the extreme, of course, there are also reasons for the increase in the bypass ratio of the engine.

However, there are pros and cons to everything, and using this technology can improve thrust and efficiency. While it can also reduce noise and fuel consumption, it also gives this technology a very big disadvantage: the weight is very impressive.

Turbofan engines with high bypass ratios are already large in diameter. The ducted casing is often close to two meters in diameter, and the CG-2000 engine is 2.5 meters long, which means that a 2-meter-diameter and 2.5-meter-high casing was made for this engine.

And the added weight is actually much more than that, this kind of engine also needs to make bulky inner and outer connotation airflow blenders, huge engine tail fairing cones, these things add up to a light weight? In addition, after the adoption of this technology, the aircraft's underwing pods will also need to be improved and extended. At the very least, the entire engine duct needs to be wrapped.

This huge difference in the engine pod also serves as a reason to distinguish whether the engine is equipped with this technology. (If you are interested, you can find pictures to compare the engine pod of the A340 and the engine pod of the 737, and then you can understand why this technology is so heavy)

Almost all the serial engines were equipped with this kind of thing in order to significantly increase the thrust, and now the thrust of the CG-2000 engine is to be increased to 12 tons. This is the last thing that can only be done by using this technology, and there is no way to add more weight to it.

Hearing that Chief Engineer Wen admitted that the maximum thrust model of the CG-2000 series should use this technology to achieve a thrust span of 3 tons, everyone attending the meeting had no other way, and even if this technology was used, it may not really be able to reach the thrust index in the end.

After all, it is increased from 9 tons to 12 tons on the basis of the scheme, and here it is necessary to cross a thrust bottleneck of up to 3 tons, and the thrust is already equivalent to 1.5 CG-2000 basic types, relying on this technology alone

"Yes, in order to meet the 12-ton thrust requirement, we had to use long-ducted mixed-flow nozzle technology, which can greatly increase engine thrust, but this alone is not enough. Considering that the MPC-75 was designed with a lot of space under the wings, presumably the 150-180 seat modifications will not change after that. Therefore, we can increase the diameter of the fan and increase the duct ratio of the engine to meet the final thrust requirements. ”

Hearing this, MTU was taken aback and then ate another whale, before MTU made a 1.45 diameter metal fan has reached the limit, and now increasing the diameter of the fan is another place that affects the whole body.

This means that the previous MTU use solid titanium alloy to directly mill out the blade scheme is not feasible, after all, the engine blade continues to increase the length means that the weight increases, the centrifugal force of the blade tip has exceeded the bearing capacity of the fan disk, (the reason has been elaborated in the previous chapter, not much to say here) It is doomed to continue to use the old generation of technology, and the new technology MTU is definitely not available.

The same is to manufacture large-diameter fans, the three international giants have their own unique skills, Rolls-Royce's hollow blades, GM/Snecma composite blades, Pratt & Whitney's ultra-high-strength fan disc and titanium alloy blades, these technologies are not the current MTU can do, all of them are the three giants years of experience and long-term investment to make it, and it is also the core competitiveness of this family in the large bypass ratio turbofan engine.

Now it's a newcomer to mtu, it's not surprising that he can't do this kind of technology, Yang Hui knew that this matter was not good at the first time when Chief Wen proposed the plan, and now it seems that it is

But if you don't just consider the technical capabilities of the MTU, and expand the source of technology, for example, the party that also participated in the meeting: the Ivchenko Design Bureau, it seems to be a good solution to the problem, this guy can design and manufacture the D18T engine of the same level as the RB-211, then it is also possible to provide a large-diameter fan that can be used by the CG-2000-3.

Anyway, it seems that the 12-ton CG-2000-3 engine should be launched early, at least until the 9-ton CG-2000-2 engine design is about completed, and that should be about 95 years, before that there will be plenty of time for MTU to bury himself in research, and also give Southwest Science and Industry the time to exert its subjective initiative to get this technology in Ukraine. (To be continued.) )