1 preface
It took more than 20 years to develop a high-performance engine for the air superiority fighter F-l 5 in the early 1970s and a thrust-to-weight ratio 10 engine for the next generation advanced fighter ATF (used in the 20th century) in the 1990s. During this period, the research viewpoint (guiding ideology) has undergone two major changes, that is, from simply pursuing performance to paying equal attention to reliability, maintainability and performance, and then to implementing "synchronous engineering" (or "concurrent engineering" and "integrated manufacturing and development" engineering). These two changes and three guiding ideology are summarized from the experience accumulated in engine development and field use. Take Pratt & Whitney as an example. From the development of the first F 100-PW- 100(-200) engine with a thrust-to-weight ratio of 8.0, to the development of the derivative modified F 100-PW-220 with high reliability, and then to the development of the new generation thrust-to-weight ratio 65438 of F-22.
2 Early F 100 engine
In the late 1960s and early 1970s, Pratt & Whitney Company of the United States developed a new generation of high-performance engines, namely F-F 100 engine, to prepare for the air superiority fighter F- 1 5 in the next 25 years. In order to meet the requirements of aircraft, the thrust-to-weight ratio of the engine needs to reach 8.0. Therefore, Pratt & Whitney will focus on improving the engine performance, that is, the thrust-to-weight ratio, which is the guiding ideology of F00 development. In the research and development of F 100, the engine weight was controlled as much as possible without affecting the performance, and finally the goal was achieved, making F 100 the first engine with a thrust-to-weight ratio of 8.0. When F 100 1 00 and F- 100 production F 100-PW- 100 were put into mass production and equipped with the US Air Force, compared with other engines at that time, the performance was obviously improved, especially under transonic/supersonic conditions. In fact, the thrust-to-weight ratio of fighter engines in service today is still the same as or slightly higher than that of F 100 30 years ago.
The F- 1 5 fighter used F- 100-PW- 100 (with two engines) has a takeoff thrust of 106. 13 kN, and F- 1 5 is/kloc-. The -200 with the same thrust as-100 was used in the F- 1 6 fighter (equipped with 1), and the F- 16 was equipped with the US Air Force at the end of 1978.
The performance of F 100 is really good, but the reliability and durability can't keep up with the improvement of performance. After the F 15 fighter is equipped with troops, many serious problems affecting the reliability of the engine are exposed in use. For example, compressor stall, overheating of a large number of turbine blades, burns, etc. , making a large number of F- 15 fighters unable to take off, which has also become one of the most difficult problems plaguing the US Air Force, making the US Air Force have to let (ge Company use the core engine of F- 10 1 for the B-l bomber, and develop F- 1 5, F/KLOC.
There are many reasons for the low reliability of F 100-PW- 100/200. For example, in use, because the aircraft needs to push and pull the fuel valve stem back and forth, the temperature and speed of the engine change rapidly, resulting in multiple stress cycles in the main components of the engine. At that time, the military engine type test only included several cycles of durable test run. Because in the early 1970s, the standard test run was 150h, and the purpose of this test run was to assess the engine's working ability at high temperature in the longest steady-state time, not to assess the working ability under multi-cycle conditions. So there are still many faults in the engine after the test run. Of course, the main reason is that in the development, we simply pursue high performance, ignoring the problems of reliability, maintainability and durability, and the design of the engine does not take into account reliability, maintainability, cost, productivity and performance.
3 F 100-PW-220 engine for improving reliability
Pratt & Whitney learned a very important experience from the problems encountered in the development and use of F 100-PW- 100.
That is, ignoring reliability and maintainability and simply pursuing performance to develop advanced engines is not feasible. In order to make the F 100 engine meet the needs of the air force with high reliability and high performance, Pratt & Whitney began to improve the F 100 engine to improve its reliability.
From 1975 to 1980, Pratt & Whitney and the US Air Force made some minor improvements in improving the reliability of F 100, but the effect was not significant. It was not until 198 1 year that F 1O0 was greatly improved by using advanced technology to improve its reliability, durability and safety. These improvements include: the redesigned "life extension core machine" (ILC), turbine blades made of single crystal materials, the first full-function digital electronic regulator (FADEc) for fighter engines, and fuel pumps made of gear pumps. This improvement is named F 100-PW-220, and its thrust is 100, that is, the takeoff thrust is 106. 13 kN, but the weight is increased by about 6 1KG, that is, the thrust-weight ratio is sacrificed to obtain high reliability.
In order to evaluate the durability and reliability of -220 model, three additional tests were carried out, namely, accelerated task test (AMT) at 4000 TAC cycle, durability test at high Ma and high cycle fatigue test. 3. 1.4000 TAc cycle accelerated task test (AMT)AMT test has never been conducted before. According to the flight mission profile diagram of the aircraft, the mission profile diagram of the engine is summarized, as shown in figure 1. Then the acceleration simulation test is carried out according to the position change of the throttle lever, that is, every 1 test cycle simulates the throttle change of the aircraft in battle, but the time is greatly shortened. This test is used to simulate the changes of temperature and speed of the engine when it is used in the field, as well as the changes of centrifugal load and temperature load, so as to evaluate the low cycle fatigue life of the engine and its reliability under this changeable working condition.
As an engine of a fighter, especially a high-performance fighter, one take-off and landing cannot be counted as 1 cycle. Because in aircraft combat, it is often necessary to push the throttle lever from the lowest position to the highest position repeatedly, and vice versa. In this way, during the take-off and landing of the aircraft, the change of stress on the parts is not a simple process from zero to maximum and then to zero. Therefore, TAc cycle (TAc is the total accumulation cycle, also known as tactical air force cycle, TAc= dozens of L/4 full throttle transitions of the total takeoff cycle, and generally L engine flight hours (EFH)=2TAc cycle) is adopted to calculate their low cycle numbers.
At present, as the engine of fighter, it needs to complete 4000 TAc cycle tests. In the development test of F 100-PW-220, the US Air Force carried out the AMT test of 4000TAc cycle according to the requirements of field use. The AMT of 1 TAc cycle takes about 15 minutes, and the AMT of 4000 TAc cycles takes 1000 hours. If each aircraft uses 250 h AC cycle, that is, 500TAC cycle, then 4 000TAC cycle AMT is equivalent to 8 years of field use. In fact, before and after F 100-PW-220, AMT with 4000TAC cycle was carried out twice. In the 1 test of 4000 TAC cycles, 953 h was tested in 90 days, including 84849 full throttle transitions, 8254 afterburner ignitions and 3455654 accelerations. After the test, the core engine was in good condition, so the second TAC cycle test was carried out for 4000 times, and the second TAC cycle test was 8 19 1 time, 1826 h, in which the whole throttle transited 172847 times. After-ignition 19308 times, the engine accelerates. In the two tests, the replacement rate, idle stop rate and thrust loss rate caused by the core engine are all zero, which shows that the engine has achieved the purpose of improving reliability. It is said that this is the 1 engine that has passed 4000 TAC cycle tests twice in fighter engines.
Through these three tests, it is shown that the reliability and durability of -220 have been greatly improved compared with-100, and there is no need to adjust the engine regulation system in the outfield (because its FADEC has self-adjusting characteristics), and some restrictions on moving the throttle lever have been removed, which can meet the needs of the air force. -220 was officially put into production at the end of 1985. Because the -220 model has good reliability in use, the US Air Force requires Pratt & Whitney to modify the 100 model used in the field with the improvement measures of the -220 model. This improved engine is named F 100-PW-220E.
4. Integrated manufacturing and development, concurrent engineering and concurrent engineering.
The F 100 engine was improved from-100 to -220, and the reliability was greatly improved. This measure of sacrificing performance to improve reliability has been praised by the Air Force. This is the first change in the development view of aero-engines, that is, from simply pursuing performance to paying equal attention to reliability, maintainability and performance, that is, the developed engine is designed in a balanced way in terms of reliability and performance.
However, it is not perfect when developing the -220 model. Although it has achieved a balance in reliability, maintainability, durability and performance, it has become a balanced design. However, due to the adoption of some advanced technologies, we encountered troubles in the formal production transformation, that is, many major problems appeared in the organization of production in the production period of 1 year (1986), and as a result, great efforts were made to overcome them before the production work was carried out, which not only delayed the time of putting them into use, but also increased the extra cost. This is an important lesson learned by Pratt & Whitney in the development of Model -220, that is, it is not enough for designers to participate in the development of a new type of engine, especially when many advanced technologies are adopted. According to the lessons of Model-220, Pratt & Whitney made a major change in the concept of engine development (guiding ideology) in 1987, and established the concept of "design to processing", which made all aspects of the engine design process be comprehensively considered at the beginning of the design, so that the advanced engine that passed the verification on this basis could be quickly transferred to cattle production and put into use. On the basis of Pratt & Whitney's new ideas, the US Air Force adopted a broader concept of multi-functional team in 1990, including all kinds of personnel involved in the whole engine life cycle from scheme demonstration to on-site support.
This systematic process, in which dozens to hundreds of multi-functional groups participate in the whole process of engine development, is called IntergraTCD product development (IPD) project, and its ultimate goal is to make users get a balanced product in all aspects. According to Pratt & Whitney, the company has applied the IPD concept to the development of various military and civil engines.
Coincidentally, at the same time, other big companies have made similar changes in their guiding ideology and adopted ideas similar to IPD. For example, GE introduced Concurrent Engineering (GE) and Rolls-Royce introduced Concurrent Engineering (SE). The names of the three companies are different, but the contents are basically the same. Take concurrent engineering as an example, it is conducted by the Defense Advanced Research Projects Agency (DARPA) and the Research and Development Center (GE- CRD) of the Aeroengine Department of General Electric Company. They believe that concurrent engineering is a revolutionary engineering development method, which considers the problems of research, development, design, manufacture and use at the same time, so as to understand the influence of adopting high-tech and advanced materials and processes on the final results of parts in a short time, so as to quickly obtain the optimal design, and shorten the cycle from scheme design to forming usable products from 1/3 to 1/. Of course, this study of conceptual renewal
The work is also an expensive project, and only 1988 ~ 1992 invested 93 million dollars in the preliminary research. DARPA has set up the Concurrent Engineering Research Center (CERC) in the University of Ciglia, and a joint research team composed of aero-engine department of GE, Carnegie, Mellon University and Ray Selous Institute of Technology has conducted cooperative research. In addition to the above units, there are nearly 20 units involved in this research and development work. IPD or CE and SE are not only used for the development of advanced military engines, but also for the development of new civil engines. For example, PW4084 (Pratt & Whitney), GE90 (General Electric) and Trent 800 developed by three major engine companies for Boeing 777 twin-engine passenger aircraft respectively. In terms of engines, IPD and other projects have been adopted. In order for Boeing 777 to be recognized by 180 mine tops of FAA at the initial stage of service (the current standard is120metops). The engine must have: the cumulative working time is not less than 250 thousand hours, and the idle stop rate is less than 0.04 times/1000 h; The conditions of 180minEPOPS are as follows: 1 20metops has1year experience, and the idle stop rate is lower than 0.02 times/1000h). The three companies adopted, ce and SE respectively to improve the reliability of engines and achieve the goal of zero idle stop rate. Luo also developed Trent 800 wind with SE, which is called the second generation wide chord sandwich structure.
The development of fan blade and combustion chamber is called the fifth stage, and the hollow titanium alloy wide chord fan blade developed by Pratt & Whitney for PW4084 also adopts IPI), which makes the development work completed in less than 2.5 years. If it is carried out according to the traditional method, it will take 5 0 years. At that time, more than 70 multifunctional teams participated in the development of the blade. GE company developed a hollow titanium alloy blade by using CE, and its development cycle was shortened by 60% compared with the conventional process.
5.F 100-PW-229 engine
In order to further improve the performance of F- 1 5 and F- 16 fighters, the US Air Force put forward the "Engine Performance Improvement Plan" IPE. For this reason, Pratt & Whitney has made great improvements to Fl00 engine, quoted advanced technologies used by many civil engines PW-4000 and technologies verified by other verification machines, and developed F 16. The -229 model has the veranda size of-100 model, which maintains the high level of durability and reliability of -220 model, but the takeoff thrust is greatly increased, reaching 129 kN, which is about 22% larger than that of -220 model, and the acceleration performance is also obviously improved. Table 1 lists the performance comparison of the two engines under various working conditions, and Figure 3 shows the acceleration comparison of -229 and-100 and -220.
In the design of -229 model, the fan with increased flow, the second generation electronic regulator, the compressor with high flow and high performance, and the external pipeline design for "users' friends" (maintenance) were adopted. All the improved components were verified in some technical verification plans. For example, the fan was designed and tested as part of the American Air Force Engine Model Derivation Program (EMDP). It has passed the durability test of 4000 TAC cycles and was tested on NASA F- 1 5. The afterburner is also the product of this project. Combustion chamber and turbine blade technology have been tested in ATECG plan of "Advanced Turbine Engine Gas Generator" and JTDE plan of "Joint Technology Verification Engine".
When developing the -229 model, Pratt & Whitney learned the experience and lessons of the -220 model, adopted a "design-to-manufacture" team in the design, and absorbed the participation of manufacturing engineers at the beginning of the design and development, so there were not many problems when 1989 was switched to production. Compared with any engine before Pratt & Whitney, its transition to production is the smoothest.
After the -229 model was put into production, IPE92 was tested in the improvement and derivative work of F/KOOC-0/99/KOOC-0/year, and its thrust reached/KOOC-0/42.5 KN.6 F/KOOC-0//KOOC-0/9-PW-/KOOC-0/00.
6. Conclusion and some opinions.
From the development process of F 100 engine, the following conclusions can be drawn:
(1) It is the trend of engine development to widely adopt mature high technology and comprehensively consider various factors to achieve balance.
(2) It is also an important measure to improve the performance and reliability of the engine by attaching importance to the previous experience in design, use and maintenance, and constantly summarizing, inducing and applying it to the newly developed engine.
(3) The concept of aero-engine development (that is, the guiding ideology) has experienced three views and two major changes in more than a quarter of a century, that is, from simply pursuing performance to paying equal attention to reliability, maintainability and performance, and then implementing integrated manufacturing and development engineering (or parallel synchronous engineering). At the same time, it also pays special attention to the experience of field use and maintenance, which is taken into account in the design.
(4) Pay attention to the development and research of high-tech application in engines, especially the verification of high-tech, as a technical reserve for developing new machines and improving old ones in the future.
⑤. Pay attention to the experience and lessons of two changes in foreign engine development views, and consider the development of engines comprehensively and in many aspects, instead of taking the development road of "emphasizing (energy) over structure" (structure and strength) or "ignoring" only performance over structural strength.
⑥ At present, the three major foreign aero-engines can carry out integrated manufacturing and development engineering or parallel synchronous engineering, which has shown its important role in the development of new military and civil engines, which not only makes the new engines have higher reliability, maintainability and performance, but also greatly shortens the development cycle and greatly reduces the life cycle cost. Therefore, we should not ignore this new thing. Under the condition of limited funds, we should also take necessary measures to carry out research work in this field, so as to change our research methods and fundamentally promote the development of aero-engines in China.