Jet-deflector servo-valve is known for high resistance to contamination and is widely used in aerospace where reliability is critical. However, the internal structure of jet-deflector device is very complex which makes it more challenging to a performance indication. When Computational Fluid Dynamics is introduced into an analysis of a jet-deflector servo valve, the dispersion of experimental data is always intolerable for a precise verification because of manufacturing or assembling accuracy. In this research, a distribution of experimental results is presented. After a comparison of different turbulence models, the low Reynolds number k-ε model shows more precision in pressure characteristic analysis of jet-deflector device.

For the flaged structure used in the fully friction stir welded tank bulkhead of the next-generation launch vehicle, strain measurements are conducted at typical locations during the flange assembly, welding, repair welding, and hydrostatic testing processes. Additionally, finite element analysis (FEA) is performed to simulate the internal pressure loading of the tank bulkhead. The test results reveal significant non-uniform stress distribution in the flange fillet area after welding, while full stirring repair welding has a relatively small influence on the final stress level of the flange. Under internal pressure loading, the flange exhibit uneven stress distribution, leading to localized yielding at certain points. The experimental results validate the accuracy of the finite element method, demonstrating its applicability for evaluating the effectiveness of subsequent structural optimizations.

Implementing the commercial space development strategy of China, the commercial space development posture over the world is analyzed. Meanwhile, the construction demand of the launch site of the commercial space is analyzed. A conception building a LOX-methane launch site in Jiuquan Satellite Launch Center is proposed. The launch site can meet the demand of dynamical system test run, test and launch of LOX-methane launch vehicle. A conceptual design program of the LOX-methane launch site is brought forward. The program includes assorted launch vehicles, general technical indexes, basic test-launch mode, site selection, general safety, and major constructions. The demonstration shows, the conceptual design program can meet the need of launch mission, and the construction scale is moderate. The conceptual design program can fulfill the demand of the programed LOX-methane launch vehicles in China. Using the launch site, a ZQ-2 launch vehicle is flying to the space in December 2023. The above demonstration can provide referential experience for the construction of analogues commercial LOX-methane launch site in China.

The cryogenic coupling is the key equipment between the rocket and the ground filling system. It is mainly used for the filling, draining,venting of cryogenic propellant, such as liquid hydrogen, liquid oxygen, liquid methane, etc. The sealing reliability of the cryogenic coupling is crucial to the launch mission. According to the application characteristics of cryogenic coupling, the performance parameters and structural parameters of the metal bellows are proposed.The stiffness, strength and fatigue life of the metal bellows are obtained by theoretical calculation. The stress distribution, contact state, stiffness and residual deformation of the metal bellows at normal temperature are obtained by simulation analysis, and the influence of low temperature on the stress and stiffness of the metal bellows is analyzed. The stiffness test, life test and performance tests of the cryogenic coupling are carried out, and the test data are in good fit with theoretical calculation and simulation analysis. The feasibility of the application of the metal bellows in cryogenic couplings for the seal compensation is verified.

Magnetic integration technology is an important approach to achieve high power density because it reduces the number, volume and weight of magnetic components in power converts. A planar transformer structure and parameter design method are proposed based on matrix magnetic integration schemes for CLLLC resonant converters, such as large volume, small leakage inductance adjustment rage, etc. The structure adopts a combined winding placement method, integrating the primary and secondary resonant inductor, excitation inductor, and transformer into one magnetic component. The primary and secondary resonant inductance, excitation inductance, and transformer turn ratio adjustment and control are achieved by controlling the cross-sectional area of the magnetic core column, the combination of winding turns, and the air gap. The experimental results show that compared with discrete magnetic components, the proposed matrix magnetic integrated structure has the same function and effectively reduces the volume and weight of magnetic components, which can provide a reference for the lightweight and miniaturized design of servo power supplies.

Movement of vehicles in the gas and liquid flow field is widely existed in the research equipment. In order to investigate the typical motion process of underwater vehicles, unsteady numerical calculation method is used to study the flow field and the active cavitation process. The calculation results show that the oscillating flow field of high or low pressure is formed in the rear edge of the vehicle in the background flow field, meanwhile the forward movement of pressure along the boundary layers significantly affects the wall pressure distribution. The active cavitations divide the flow field into the main influence zone, secondary influence zone, no influence zone and wake zone. The pressure in the main influence zone remains almost unchanged, whereas increasing in the secondary influence zone in a stepped manner. The active cavitation can eliminate the wake influence to a certain extent, making the upper and lower wall pressure changes consistent, weakening the asymmetric force of the flow field on the vehicle body and reducing the duration of negative pressure zone. Last but not least, it can also weaken the effect of water boundary layer and reduce the resistance of the whole vehicle to the lowest when developing from the shoulder to the end.

To investigate the effects of grease degradation induced by long-term storage on the control characteristics of servo systems, the viscosity properties of the grease during storage are analyzed according to the results from the high-temperature accelerated storage test. Subsequently, the friction of the roller screw transmission is modeled to investigate the influence of lubrication degradation on the friction characteristics of servo system. Eventually, the friction models for various lubrication conditions are integrated into the servo system control simulation model to assess the impact of lubrication degradation on its performance characteristics. The obtained result is that the viscosity properties do not exhibit a clear correlation with the accelerated storage time. Selecting the degradation grease with high viscosity as the research subject, analysis indicates that the lubrication causes the increase of friction torques, the attenuation in amplitude and phase hysteresis in mid-high frequency range in servo system control characteristics. Besides, the attenuation and hysteresis aggravate as the load increases.

A long-life and high-stability grease is developed to meet the demand of long-life lubrication condition with storage requirement. The physical and chemical properties,biodegradability, bearing life and rheology of the grease are studied. The results show that compared with the commercial grease, long-life and high-stability grease has lower evaporation loss at high temperature and lower oil separation ratio, which shows that it has better volatility and colloidal stability. The wear scar diameter of SRV test is smaller, and the life of wheel bearing and FE9 is longer, indicating that it has better anti-wear performance, lubrication performance and oxidation stability. The cumulative biodegradation rate in 28 days is 1.82%, which is much lower than 29.19% of the commercial grease. The rheological tests show that it has better structural stability. The developed long-life and high-stability grease has excellent comprehensive performance and can be used in the long-life application environment with long-term storage requirements and harsh working conditions.

Manual phase shifting operation is still the main countermeasure for single pulse radar to avoid Co-frequency Signal Interference in space launch and control missions. In order to improve the accuracy of operators' judgment of interference phenomena and the timeliness of handling during target tracking, and reduce the adverse effects of Co-frequency Signal Interference, a method based on radar target signal velocity characteristics and rocket theory flight trajectory data is proposed to analyze the motion trend of other station radar signals. Compared with the actual tracking situation, this method can accurately predict the motion trend of each radar signal under normal rocket flight conditions. Meanwhile, this method also provides a feasible approach for achieving automatic target recognition for single pulse radar in the field of aerospace measurement and control.

The rapid recovery capability of launch towers and movable launch platforms is a critical factor in determining the average annual launch capability of a launch site. The post-launch recovery situation of a space launch site for previous missions is sorted out, the content and sequence of post-launch recovery projects for previous missions are fully identified, and on the basis of which the "critical path method+ECRS analysis" method is used to analyze and optimize the post-launch recovery organization mode, workflow, equipment and facilities, and to put forward specific improvement measures and optimization plans to better improve quality and efficiency for the launch site. On the basis of this, the organizational mode of post-launch recovery, workflow, equipment and facilities are analyzed and optimized by using the "critical path method+ECRS analysis" method, and specific improvement measures and optimization plans are proposed to improve the quality and efficiency of the post-launch recovery and effectively enhance the annual launching capability of the launch site.