The 12th air show (2018 China International Aviation & Aerospace Exhibition) opened November 6 in Zhuhai. A test plane of a J-10B Chinese-made vector-controlled fighter was shown for the first time. Chengdu twin-jet J-10B multirole fighter demonstrated the Shenyang Aircraft Corporation’s WS-10G thrust-vectoring turbofan engine with an aerobatics demonstration that included the Pugachev’s Cobra maneuver. The new thrust-vectoring engine increases the J-10B’s agility and could give the fighter an edge when engaging hostile aircraft.
Foreign-made engines presented at the exhibition deserve attention as well. The Beijing-based Tianjiao Aircraft Building Company, Chongqing Aircraft Engine Company owned by Tianjiao, as well as the famous Ukrainian Motor Sich JSC took part in the air show once again. A separate pavilion (#6) was allotted for them, in which four aircraft engines developed by Motor Sich JSC were represented, including AI-25TLK engines with a small bypass ratio, TV3-117VMA-SBM1V helicopter engines, D-436-148FM turbofan engine, as well as MS-500V-S turboprop engines.
The scope of aircraft engines is very extensive, so China needs to cooperate with foreign companies. In recent years, China has achieved some success in it, but this is still not enough to catch up with the level of other countries. Motor Sich JSC is a large company in the field of aircraft engine manufacturing, which has inherited Soviet technologies. Given the experience gained by this company, China has a lot to learn from it.
Turbofan engine D-436-148FM
Speaking about the four models of aircraft engines submitted by Motor Sich, many might have noticed that the AI-322 engine could be installed in an advanced jet trainer (AJT) L-15, and the TV3-117VMA-SBM1V engine can be used in Mi-8/17 and Ka-28/31 helicopters, widely used by People's Liberation Army. However, this article’s author is sure that the most significant among these engines is the unremarkable D-436-148FM turbofan engine used in civil aircraft.
Unlike aircraft engines, which China has been producing until now, the D-436 engine has a triple-spool compressor. The difference between an engine with a triple-spool compressor and a turbofan engine with a two- spool compressor is not that the fan system is attached directly to the low-pressure stage rotor, but that another special rotor is added to the turbine, which drives the fan in the act.
In other words, three coaxial rotors are installed in a triple-spool engine: a low-pressure central turbine that rotates at low speed and drives a fan; a high-pressure turbine that rotates at high speed and drives a high-pressure compressor is installed outside.
Unlike a turbofan engine with a two-spool compressor, the three rotors can operate separately at optimum speed, which reduces the number of rotors, blades, and adjustable blades. Due to the decrease in the number of rotors, their length is reduced, the hardness increases and the wear rate decreases. All this effectively reduces fuel consumption, and, consequently, increases the operational features of this engine.
When speaking about a triple- spool compressor engine, many would remember Al-Bi211 (RB211) and Rolls-Royce Trent (Rolls-Royce Trent) engines developed by the British Rolls-Royce. However, not only the UK successfully produced three-stage turbofan engines; the Soviet Union was also producing these engines.
Three development laboratories were engaged in elaborating turbofan three-shaft engines in the Soviet Union. PJSC Kuznetsov is located on the territory of modern Russia; its symbol was the turbojet engine with NK-321 afterburner chamber, applied in Tu-160 strategic bomber. Ukraine is the second place, where these engines are produced. Now it is part of Motor Sich JSC, Zaporizhia Machine-Building Design Bureau Progress State Enterprise named after A.G. Ivchenko, where D-36 engine, the D-436, the predecessor was developed.
In the early 1970s, Progress State Enterprise named after A.G. Ivchenko was instructed to design the engine unit for the An-124 heavy transport aircraft, which was was being developed. After some thought, chief engineer of the bureau Volodymyr Lotarev concluded that the task could be completed only under the condition of using a three-shaft engine.
In order to acquire the production technology of a three-shaft turbofan engine, Lotarev decided to start with the development of a small D-36 engine, the full output of which was 6,500 kilograms. This engine is successfully used in Yak-42, An-72, An-74, and others aircraft.
Having harnessed the relevant technologies, the design bureau started the production of the D-18 engine based on the D-36, which had a greater burden. Due to this, the An-124, and later the An-225 aircraft, obtained a reliable propulsion system.
In the early 1980s, Progress State Enterprise named after A.G. Ivchenko began designing the D-436, a new version of the D-36 turbofan engine. This engine was first tested in 1985, and in 1987, it was finally approved. The D-36 was much improved; a new compressor, a fan system, and an electronic digital engine control system were installed.
Today, this medium-thrust turbofan engine has replaced the D-36 in Yak-42, An-72, An-74 aircraft, and is also widely used in Tu-134, Tu-334, An-148 passenger aircraft, and in the Be-200 multipurpose amphibious aircraft.
What’s the benefit from harnessing these technologies?
Acquiring technologies related to the D-436 engine can bring the Chinese aviation industry a lot of advantages.
Firstly, despite the outstanding characteristics of three-shaft turbofan engines, from the point of view of structural dynamics, all three shafts rotate with a high speed and power. Speaking about the control coordination, there is vibration, resonance, and critical speed of the three shafts, which brings a lot of difficulties. These technologies represent a challenge for the aviation industry and also indicate a certain level of technological development. In the US, no engine development of this type has been conducted to date, which proves what was said above.
Accordingly, if China succeeds in harnessing the technology of the D-436 turbofan engine, we can assume that along with this, China will gain knowledge regarding three-shaft engines that have been accumulated in the Soviet Union for decades. And it will be an undoubted advantage for the aviation engine industry.
Secondly, the D-436 engine is an excellent example of a turbofan engine with medium thrust and high bypass ratio. Based on its characteristics, we can assure that it is fully capable of replacing the American CF34-10A, produced by General Electric, in the Chinese regional passenger ARJ-21 aircraft. Thus, the ARJ-21 will receive another reliable engine. If it happens that for some reason, the supply of CF34-10A engines to China stops or they can no longer be used, for example, in the development of a military model, then China has no better alternative than the D-436.
It goes in parallel with CF34-10A and D-436. Obviously, the D-436 is significantly bigger, consumes more fuel, and has a stronger thrust-to-weight ratio.
Thirdly, during the development of the D-436 engine, Motor Sich company applied technologies involved in other engines.
As already mentioned, the predecessor of the D-436 was the D-36 engine, the enhanced version of which, namely the D-18, was used in An-124 and An-225 aircraft.
Therefore, if we build upon D-436 and modify it like D-18 engine (out of D-36), then we will get an updated version of the D-18 turbofan engine with a large load. Two such engines would be enough to improve Y-20 aircraft. This engine can be an alternative power plant for wide-body passenger aircraft CR929, jointly developed by Russia and China.
However, more important is the fact that when creating the D-436, Motor Sich embodied the key design ideas, and if we build upon D-436 engine, we get the turbo-charged D-136 used in the famous heavy Mi-26 helicopter and in An-70 military transport aircraft (D-27 is a three-shaft propfan engine). Thus, when mastering the production technology of the D-436, China gets knowledge of four modern engines.
According to Tianjiao representative, four presented engines might be produced in China. It is hoped that this will be the same good opportunity for the production of aircraft engines, as the introduction of the Ukrainian GTD 25000 gas turbine engine, which will fill the gaps in the production of three-shaft, heavy turboshaft and fan motors and contribute to the rapid development of this industry.
Read the original text at guancha.cn.