readx;?“ Although I don't know whether this technology has been tested in the actual test of this large bypass than turbofan fan, but after thinking about the technical principle a little, I feel that it is still more reliable and worth a try! “

The advantage of the large and small blades is that it can do what other blades can't do, so that the roots of the blades with the lowest compression efficiency of other blades can also make the compressor carry out effective airflow compression because of the existence of small blades, which is the essential advantage of the large and small blades, and it is also why the previous four generations of military thrust can be equal to the American F119 engine in terms of compressor efficiency. Pen, fun, pavilion www. biquge。 info

The large and small blades make up for the lack of aerodynamic efficiency at the root of the large blades through the small blades, so as to improve the compression efficiency of the compressor as a whole.

But what I didn't think about was that the current United Aero Engine Company has played the technology of large and small blades so slippery, not only on compressors, but even now even on fans, and not only use, but also more handy, just right.

Now we must first understand one thing: with the continuous progress of technology, the fan used in the large bypass ratio turbofan engine has undergone great changes in blade modeling and manufacturing, and the changes in the manufacturing process are various schemes such as hollow / honeycomb cooling / titanium alloy / composite materials.

However, with the development and progress of blade manufacturing technology, the related blade aerodynamic modeling is also constantly developing, including the simple swept blade used in the previous CG-2000, which was definitely the top technology at that time in the CG-2000 engine era.

With the introduction of simple swept fan blade technology at that time, it did add a lot of color to the CG-2000 engine, and with the improvement of efficiency after the introduction of new blades, the number of fan blades installed was also greatly reduced.

However, the blade technology of CG-2000 is not the most advanced now, for example, Yang Hui knows the situation now, the 0112 Institute is developing a more advanced scimitar-shaped wide-chord swept fan blade shape together with several other units in the field of fluid mechanics that have in-depth research, and the new blade modeling efficiency will be higher, and the number of fan blades may continue to decrease under the same circumstances.

As the number of engine blades decreases, the gap between the blade roots will be larger, and the large and small blade technology will be used relatively more smoothly, and the aerodynamic efficiency of the small blades will be higher.

The above is the expected effect of the large and small blades after being used on the fan stage, Yang Hui probably inferred like this, and then the answer given by Chief Engineer Jiang Hefu is actually the same as Yang Hui's speculation.

"This time, the idea of using the large and small blade technology in the turbofan-driven fan was proposed by the 0112 Institute, and we are only a member of the multi-party cooperation of the project, but the technology has been found to be feasible after various verifications. In a turbofan engine with large bypass ratio with super thrust, the diameter of the fan is usually several times the diameter of the compressor, and the actual cross-sectional diameter of the compressor at the back of the fan is actually only the root of the fan, which is the least efficient. “

The large bypass is less aerodynamic than the root of the turbofan engine, and it corresponds to the gas compression of the entire compressor that is crucial later, which has not been a good solution, but with the large and small blades to solve the problem of low aerodynamic efficiency at the root of the fan, in fact, many problems can be solved.

At this time, when it comes to gear transmission technology, Yang Hui seems to be a little worried about the previous waver in his heart, with the overall technical scheme of the engine given by the design team, they may really have a relevant way to cleverly solve the problem of gear reducer.

"Okay, now that you plan to use gear transmission technology, then you must also know the advantages and disadvantages of gear transmission technology, although in theory the gear transmission can meet the differential operation between the fan of the turbofan engine and the medium pressure compressor, and achieve infinity, but in fact you must also know the problems encountered, so let's talk about how to solve it now?"

Straight to the point, if there is a reliable solution this time, then the ultra-large thrust turbofan engine project will be almost completely equipped, Yang Hui will definitely not hesitate to choose to start the project immediately, and immediately start the development of the core machine, and other key technologies will definitely follow up immediately, and various resources will definitely be given priority.

After all, the ultra-high-speed and heavy-duty gear transmission technology is not a great test of the technical level of the basic industry, and it is normal for the industrial modernization time of the republic to be less than a few decades old, and it is normal to have some deficiencies in the accumulation of all aspects.

Therefore, when asked how to solve the inherent problems of gear transmission technology, Yang Hui's answer can only be a fact rather than a meaning, or more to give people a feeling that we have done our best.

"For the gear reducer, although this is also not our 624 Institute's responsibility, but I have heard it when I discussed it with the 2 Institute before, and it seems that the opinion there is that due to the development of fan blade technology, the length of the blade can be made longer, and even the diameter of the entire fan can be guaranteed to reach about 3 meters. This is enough to meet the requirements of the engine for the use of the fan, and even a little exceeded, when the project must be the first to develop a basic model with the smallest thrust, so we first accommodate the requirements of the reducer, and the reduction ratio between the medium pressure compressor and the low pressure fan can be relaxed. “

For the solution of gear transmission technology, there are not only the above technical compromises, but also the chief engineer of the 624 Institute Jiang Hefu for the project, but also all kinds of fights, such as just agreed to cooperate with the German MM company turbofan 12C project, here immediately thought of the idea of the Germans.

"And the reason why we can't make a gear reducer that fully meets the requirements is that the material processing difficulty of the reducer is not much to say, and the processing capacity provided by our domestic metal machine tool industry is also difficult to ensure the processing accuracy of the reducer, so I think I can take this opportunity to exchange some advanced metal processing technology from Germany, so that after we increase the machining accuracy, the performance of the gear reducer should also improve. (To be continued.) )