The test run of the needle bolt injector was successful
The test run of the Blue Arrow Aerospace liquid oxygen methane needle injector was a complete success. It is also the first in China to pass the full hot test run verification. Liquid oxygen methane needle injector.
As we all know, in order to successfully develop a retractable launch vehicle, you must first have a rocket engine that can adjust thrust on a large scale, and needle injection technology is the engine's ability to achieve depth-variable thrust. One of the core skills.
Since its introduction in the 1970s, needle injection technology has been widely used in lunar descent engines. After the establishment of SpaceX, CTO Tom Mueller applied pinbolt injector technology to the launch vehicle main engine-Merlin series engines for the first time. This was also one of the important innovations of the Merlin engine. For more than 10 years, due to the simple structure of the Merlin engine injector, excellent combustion stability, and easy realization of variable thrust, it has provided strong power support for the repeated use of Spacex Falcon rockets.
Compared with traditional DC and centrifugal injectors, pin-bolt injectors have the following characteristics:
Achieve depth variable thrust to assist rocket recovery
By moving the needle pin, the oxidizer and fuel flow areas can be changed at the same time, stabilizing the oxidizer and fuel injection pressure drops under various working conditions. In theory, variable thrust from rated thrust to zero can be achieved, providing a retractable power solution for the rocket.
Simple structure and low cost
The pin-bolt injector consists of four parts: the shell, the core barrel, the center rod and the flat head, while the direct-flow and centrifugal injectors The number of nozzles can be increased from dozens to hundreds, thereby significantly reducing costs.
Excellent combustion stability
In public information, needle-type injectors have never suffered from combustion instability, a global engine problem.
Using needle-type injectors on liquid oxygen methane engines is also a technical problem that Blue Arrow Aerospace engineers have been overcoming. However, liquid oxygen methane needle injectors belong to a new field in China. Methane operation is in a supercritical state, similar to "liquid-vapor" injection, which is extremely difficult.
In addition, the increase in methane temperature during the operation will cause the density to drop from 440kg/m3 to 20kg/m3, the injection speed to increase from 30m/s to 140m/s, and the product injection atomization The situation will change drastically, so if the parameter selection is slightly unreasonable, the combustion efficiency will be low, and even ablation will occur.
Preliminary ablation statusPreliminary ablation status
Through the efforts of Blue Arrow engineers, various difficulties were finally overcome and landmark results were finally achieved. During this test run, the product burned for a total of 230 seconds, including 200 seconds for the long-range test run. The product incineration power reached more than 97%, and the maximum vibration was 20g. During the test run, the parameters were smooth and no ablation occurred, reaching the practical engineering level. In addition, this test run also carried out a test run with ultra-low injection pressure drop (0.1MPa) in the fuel path, and no combustion instability occurred, which once again proved the outstanding combustion stability of the pin-bolt injector.
Injector condition after test runInjector condition after test run
Test run curveTest run curve
The success of this test run marks:
Blue Arrow Aerospace is the first in China to master the core technology of liquid oxygen methane engine depth variable thrust. This technology can greatly expand the thrust variation range of Tianque engine and provide a better solution for the recovery of the Suzaku-2 rocket;
Blue Arrow Aerospace will transplant this technology to the Tianque 80-ton liquid oxygen methane engine injector, which will significantly reduce engine costs;
The benefits of this technology as existing aerospace technology The addition provides another technical option for the planetary landing descent stage engine.
Popular Science Tips
Needle-bolt injector-the engine depth variable thrust artifact?
The needle-bolt injector originated from some early experiments Chamber device, in 1960, TRW began to develop a needle plug injector, and its design patent was not publicly announced until 1972. In the past 40 years, TRW has conducted hot tests on at least 60 engines, with thrust ranges from 22N to 290t. The most famous engine is the Apollo manned lunar landing descent stage engine LMDE, with a thrust range of 4.7t. ~0.47t.
Different from DC impact injectors and centrifugal injectors, the medium flow area of ??the first two injectors is fixed, and the limit of the thrust ratio is 2.5:1. When the scale is expanded to low working conditions, The decrease in injection pressure drop will cause low-frequency unstable combustion; the pin-bolt injector can control the injection of fuel and oxidant under various working conditions by moving the parts of the injector and changing the injection area of ??oxidant and fuel at the same time. Injection pressure drop, so it is the best choice for the injector technology solution of depth variable thrust engine.