In November 2018, Jiuzhou Yunjian’s “Lingyun” liquid oxygen methane rocket engine thrust adjustment system successfully completed the first round of semi-physical simulation tests. The core components of the variable thrust such as the engine thrust controller, regulating valve driver, and electric regulating valve were carried out at the system level. The test fully verified the work matching of the thrust adjustment control system and the engine system, the functional adaptability of the control drive, and the rationality of the control logic. The completion of this round of semi-physical simulation test is the first breakthrough of semi-physical simulation technology in the domestic pumping liquid rocket engine field, laying a solid foundation for the development of variable thrust engines.

Semi-physical simulation test site

The following results have been achieved through this semi-physical simulation test:
The engine control and motor drive adopt an integrated design scheme, which greatly simplifies the system and reduces the weight of the control system;

Control drive
The low-cost electric control valve with independent intellectual property rights has broken through the key technologies of electric control valve high-pressure dynamic sealing, fast response, and vibration resistance;

Electric control valve
Independent development of motor drive and engine variable thrust control software to realize independent controllability of core technology;
A variety of control algorithms that can adapt to the overall requirements of the rocket, and can be selected according to the needs of the rocket's different missions;
An engine semi-physical simulation model that meets the requirements of real-time and calculation accuracy.
 
Rocket recyclable technology is an important way to reduce launch costs. Commercial aerospace companies represented by SpaceX and BlueOrigin in the United States have vigorously developed rocket recyclable technology, and have greatly reduced launch costs through partial recovery and reuse of rockets. For the rocket to be recoverable, the power system must break through at least two key technologies: one is the engine's multiple ignition and starting technology. The rocket uses multiple engine ignition and other measures to control its trajectory during the return process and return to the scheduled landing site; the other is the engine. The deep thrust adjustment technology realizes the rocket deceleration process control through the engine's variable thrust during the rocket's return and landing process, and meets the requirements of the rocket's safe landing speed. At the beginning of the design, the Kyushu Yunjian "Lingyun" liquid oxygen methane engine was designed with repeated use as the core design concept. It is in line with the international advanced level. The engine has dozens of starting capabilities, and the thrust can achieve stepless performance in the range of 30%-100%. Tune.
The half-physical simulation test of the thrust control system is another verification test carried out by Kyushu Yunjian following the torch-type electric igniter test and the variable thrust long-range test of the engine auxiliary system, focusing on the core technology of the low-cost and reusable commercial carrier power system. The completion of the hardware-in-the-loop simulation test indicates that Kyushu Yunjian has broken through the control bottleneck in the depth variable thrust technology of the pumped liquid rocket engine, and has initially mastered the engine thrust control technology that realizes the recovery of the launch vehicle and the reuse of the power system. The whole machine thermal test verification of variable thrust technology has laid a solid foundation.
 
About semi-physical simulation:
Semi-physical simulation originated in the aviation field, has been developed for more than 20 years, and has been widely used in the industry. It connects some mathematical models and actual equipment to operate together to form a simulation system. Through the semi-physical simulation test, one can avoid some simulation errors caused by system modeling that cannot be completely and accurately described by mathematical models, solve the problems that mathematical simulation cannot solve, and can make full use of complements each other. The role of mathematical simulation; second, system-level simulation testing can be carried out in the component product development stage, reducing the risk of component supporting systems, significantly increasing product iteration speed, shortening product development cycle and reducing development risk, so in control system simulation, Hardware-in-the-loop simulation is an essential and important link.

Schematic diagram showing the principle of hardware-in-the-loop simulation