The optics window is usually faced with severe aerodynamic heating, and there is a prominent image saturation problem because of high temperature. Therefore, researchers often use film cooling to isolate the direct heat convection from the outflow. A tangential high-density cooling film generation structure is designed which is used for high pressure and heat flux. Through reasonable ground test, numerical simulation and engineering calculation, the main factors affecting the cooling efficiency are studied. The preliminary results show that tangential high density gas film can reliably reduce the surface heat at high pressure and high heat flux. The research effectively adapts to the increasingly harsh optical observation environment.

To study the safety of a tower slewing platform structure, a three dimensional numerical model is established with actual sizes and operating conditions. The structural force, pressure margin of hydraulic system with different wind loads, and the influence of lift platforms’ amount are researched which are concerned closely in use. In working condition, the maximum stress of structure is ${223.98}\mathrm{{MPa}}$, and the structure safety factor is 1.58 . The pressure margin of hydraulic system is calculated with the worst wind direction and the maximum windward area. When the platform is opened with permitted wind speed, the hydraulic system pressure can not be lower than ${5.40}\mathrm{{MPa}}$, and the pressure margin is 2.96. The structure safety factor is 1.35 when the number of lift platforms is 9. According to the results of simulating calculation, the security of the slewing platform can be confirmed. The simulating model can provide a reference for the slewing platform’s application.

In order to study the mixing and explosion characteristics of liquid oxygen and kerosene, a partial confined space test system is established to simulate the application scenarios of the launch site and the tests are carried out. It is demonstrated that when liquid oxygen and kerosene are discharged and mixed at the same time, the concentration of kerosene and oxygen increases at first and then decreases. When kerosene temperature is ${65}^{\circ}\mathrm{C}$ and ignition excitation is ${5.9}\mathrm{\;J}$, even if liquid oxygen leaks, the ignition and explosion condition are still not reached at the measuring points arranged above the liquid level. In the test when the kerosene temperature is raised to ${80}^{\circ}\mathrm{C}$, explosion occurs when liquid oxygen is released only for about 20 seconds. At ignition time, the concentration of kerosene, oxygen, and nitrogen are ${1.31}\%,{40.05}\%$ and ${58.64}\%$ respectively, and the ratio of kerosene concentration to oxygen concentration is 0.033 .

Thermal protection is a regional protection measure covering the outer surface of the launch pad to prevent the bearing structure of the launch pad from being eroded by the rocket launch gas flow. It is a key link to ensure that the launch pad can reliably carry the rocket safely. In recent years, as the launch frequency of the conventional liquid carrier rocket represented by the Long March 2C rocket has increased year by year, the recovery time of the launch pad after the launch of the rocket has also been greatly reduced. Therefore, a rapid recovery scheme for thermal protection of the launch pad is proposed, which combines the ablation type heat protection technology with the absorption type heat protection technology, and the modular thermal protection components are designed to realize rapid replacement through simulation, test and use. The results show that the repair time of the new thermal protection is shortened from 3 days to 1 day, and the protection effect is good, which can meet the needs of high-density rocket launch.

Mobile Launcher (ML) is one of the critical ground supporting systems, which is going to be in service for Space Launch System (SLS). The function of ML includes stacking, assembly, process checkouts and launch support for the SLS rocket and Orion spacecraft. The structure layouts, operations and functions from Apollo and Saturn V are valued and baselined. The ground support equipment like umbilicals and accessories are researched and renewed. Besides, ML is aimed to be possessed of strong applicability and generality for different heavy-lift rockets, including SLS. The generality design is then performed, and modules and equipment are borrowed from previous launchers. Comprehensive tests of function, security and reliability are carried on. The research in the paper will provide reference for the launcher of heavy-lift rocket in China.

This article focuses on the dynamic model of air rudder rotation around the rudder shaft, considering a dry friction model with rotational clearance and Stribeck effect, and establishing the forced vibration equation of air rudder rotation with clearance and dry friction. The average method is applied to analyze the amplitude frequency characteristics of the rotational direction. The influence of different friction torque coefficients and external excitation frequencies on the amplitude frequency response of axial vibration is studied. The results show that when the external excitation frequency changes, the amplitude frequency curve of the vibration around the axis exhibits hysteresis nonlinear characteristics of different softness and hardness. Multiple solution frequency bands appear in the frequency domain, and the frequency domain multiple solution frequency bands increase with the increase of the friction torque coefficient.

In the fault-tolerant control of polyphase motors, hysteresis control is generally adopted for the more complex non-sinusoidal fault-tolerant current obtained by multi-constraint solving. Compared with hysteresis control, voltage space vector control has the advantages of low torque ripple and low energy consumption, which is more common in the control of polyphase motors. In order to solve the problem that the non-sinusoidal fault-tolerant current cannot be decoupled directly for voltage space vector control, Fourier transform is introduced and the non-sinusoidal fault-tolerant current is decomposed into fundamental current and third harmonic current to realize the decoupling transformation of the non-sinusoidal fault-tolerant current. Based on this, the decoupling transformation matrix is derived and the correctness of the processing method is verified by simulation analysis. The results show that this method can solve the problem that the non-sinusoidal fault-tolerant current under open fault-tolerant control of polyphase permanent magnet synchronous motor cannot be directly applied to voltage space vector control, so as to reduce the torque ripple and improve the motor current stability.

Modelling methods of the high-altitude wind uncertainty have significant influence on aerodynamic loads and the overall performance optimization of launch vehicles. The commonly used methods in engineering do not consider the correlation between wind speeds at different altitudes, and the simulated wind samples are inconsistent with actual wind characteristics, therefore disable to accurately predict the aerodynamic loads. A modelling method using $U/V$ wind speed components as non-stationary Gaussian processes about the height is proposed. The statistical distribution parameters of massive actual historical wind samples are analyzed, and the expansion optimal linear estimation (EOLE) method is adopted to generate wind samples with the same distribution as actual wind samples. Results indicate that the proposed method can simulate the actual wind profile more precisely than traditional methods. The simulation program of real launch vehicle is used to calculate the wind loads, and the results show that the wind loads predicted by the proposed method is far more accurate than traditional methods, which is of great significance to improve the launch efficiency and launch probability of launch vehicles.

To analyze the correlation characteristics between visible-infrared spectrum and infrared radiation of photonic crystal films, three kinds of Ge/ZnS photonic crystal films with different visible reflectance and the same infrared emissivity are designed. By simulating the infrared radiation characteristics of photonic crystal structures, the influence of solar illumination and reflection spectrum on the infrared radiation characteristics of the films in vacuum and atmospheric environments is discussed. The simulated results show that the difference of visible reflectance will lead to the discrepancy of surface temperature in the presence of sunlight. For infrared radiation, the high reflection surface will reflect solar radiation at low temperature for $3 \sim {5\mu}\mathrm{m}$ waveband, which has a negative impact on infrared camouflage. For $8 \sim {14\mu}\mathrm{m}$ waveband, when the infrared emissivity is low enough, the infrared radiation emittance of the photonic crystal structures is close. The fabrication of samples and the measurement of reflection spectrum and infrared thermography are carried out. The test results show the consistency with the simulation, and verify the infrared camouflage performance of three films. The research results are helpful to understand the visible-infrared spectrum and infrared radiation correlation characteristics of photonic crystal films, and provide reference for the spectral design and application scheme of visible-infrared camouflage materials compatible with microwave camouflage.

The stability of shipborne platform in complex sea surface wind and wave environments is an important foundation for the operation of shipborne equipment. Attitude stability control for shipborne platform, an active disturbance rejection controller is designed, which improves the tracking accuracy of the shipborne platform to the target angle, ensures the rapid response of the system, and suppresses the influence of uncertain factors such as wind wave disturbance and load disturbance. In order to further improve the control effect of the controller, the particle swarm optimization algorithm is used to optimize the intelligent parameters of the controller. The simulation results show that the ADRC can improve the tracking speed, accuracy and robustness of the system.