WJ6 Turboprop engine
Turboprop engine, also called propeller engine, is composed of propeller and gas generator and the propeller is driven by turbine. The propeller is of about 1000 rotations per minute due to its big propeller and rotation speed lower than the turbine. In order to make the turbine and propeller work in normal range, it is necessary to install a speed reducer between them and to reduce the rotation speed of turbine to one tenth, only in this way, the propeller can be driven. The speed reducer is of heavy load, complicated structure and high manufacturing cost and its weight is equal to the total weight of air compressor and turbine. As part of the whole engine, the speed reducer takes important place in design, manufacturing and test.
The Zhuzhou Aero-Engine Factory started to research turbine engine in august of 1969; the first engine started to operate in September of 1970 and tried to fly in April of 1973; finished design in 1976 and applied equipment delivery-8 plane. The turbine engine series mainly contains turbine-6 A transformation. In order to increase power, it started transformation design in 1977, manufactured the first sample machine, whose performance reached the requirements and has the annual capability of 100 sets.
Turbine-6 aero-engine is a single-shaft half-altitude turbine propeller engine and is applied as dynamics of Y-8 model plane and IL-18 delivery plane. This engine was awarded as Excellent Product in 1986. The transformed turbine-6 model aero-engine has more advanced performance and can be applied as dynamics of delivery-8 airproof plane.
- Takeoff power: 3126kw
- Takeoff oil consumption: 329g/ (kw.h)
- Mass: 1200kg
- Lube oil consumption: 0.8L/h
- Working temperature range: -60~+55C
In 1969, ZEF was tasked to develop the WJ6 engine - the powerplant for the Y-8 aeroplane which could also be used in the Soviet-made 11-18 passenger aeroplane. The take-off equivalent power was 3,124 kW (4,250 hp), and it weighed 1,200 kg. The transition from piston engine to turbine engine excited the staff and workers of the factory. With the cooperation of XEF, the design was completed by the end of 1969. In the meantime, the factory carried out technical reforms. During the construction of the WJ6 engine test cell, several thousands of the employees assisted and the work was finished 45 days ahead of schedule. In the trial production of the new engine, the technical people, workers and cardres were combined as one, and they solved 163 critical technical problems. In September 1970, the first engine prototype was built and the running test was started.
By 1973, three endurance tests were undertaken smoothly. However, the accident of the oil pipe breaking at combustion chamber casing occurred twice in the 500 hours State appraisal tests in 1973 and 1975, and caused the failure of the test. The vice chief engineer Fei Binfang and WJ6 chief designer Cai Wangshui organized an investigation and repeated tests. They found that the two causes of the oil pipe breaking were not from the engine itself. One was the reverse flow in the test cell, which caused the engine vibration and another was the improper bleeding. They took measures to correct the insufficiency of the test cell and changed the way of bleeding. The problems were cleared.
The third appraisal test was carried out in 1976, and passed smoothly. Following that was the 5 months acceptance flight test. The Y-8, which was being tested flew over 15 provinces and cities in China and covered a range of 60,000 km. They went to Hainan Island down in the South, and Hailaer up in the North. It successfully accomplished flight programs in very cold (-23.4 t ), very hot (+38.1 t ), and plateau (3,540 m above sea level) areas.
The WJ6 engine was proved to be reliable in operation and its performance met the technical specification. In January 1977, the State issued the design certificate and it was put into small-batch production. After extensive tests and studies on its components and the complete engine, measures for improvement were taken, such as: the proper adjustment of the compressor vane installation angle, the adjustment of the clearances between the individual parts of the oil system and oil pressure, and modification of the combustor ignitor, etc.. The 4 remaining problems of insufficient power, high oil consumption, high exhaust gas temperature and short TBO were solved one by one. They soon increased the first TBO from 300 hours to 1,000 hours. In 1986 it was further extended to 2,000 hours. The in-factory tests of technical improvements for life extension to 3,000 hours was also accomplished. In 1984, the engine successfully passed the flight test to Tibet. In 1980, the engine was awarded the second class prize of the National Science and Technology Achievements.
After the WJ6 engine was released for production, the aircraft factory proposed to modify the Y-8 with a pressurized cabin and to increase its pay load capacity. They requested Permission to increase the engine power. To this end, ZEF started the modification of the engine in 1977. They decided to use air-cooled turbine blades to increase TET and the r.p.m. The engine power was raised by 221 kW (300 hp) and it was named the WJ6A engine. The first prototype was built in early 1983, and after running tests, its performance reached the design value. In June the same year, the 150 hours reliability test was passed and it proved that the modification design was successful.
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