Novel hybrid ablation thermal protection coatings (FHMP‐ATPCs), employing iron trioxide (Fe2O3) powder, hollow glass microspheres, and mica powder as the fillers in hydroxyl‐terminated silicone oligomer‐bridged epoxy resins (PSG) copolymer, is investigated using an aerothermal‐vibration coupling test system. The ablation behavior and structural reliability of FHMP‐ATPCs with varying coating thickness were studied. During the test, the total enthalpy of airflow and dynamic pressures are 23 MJ/kg and 300 Pa, accompanied by the random vibration with a frequency of 20–2000 Hz and a total root‐mean‐square acceleration of 14.9g. The maximum surface and back‐face temperatures of the coating with the thickness of 2 mm reached 836.2°C and 156.4°C, respectively. Results also showed that the reduction of thickness obviously suppressed the surface temperature and increase in back‐face temperature yet maintaining high structural reliability. Compared with DGEBA‐based coatings, the PSG‐based coatings showed excellent structural reliability during the test. The study provides a solution for obtaining high performance ATPCs, which are highly desired for supersonic vehicles.

Thermoelectric generator (TEG) can utilize intermittent temperature fluctuations of the aircraft's fuselage to provide power for wireless structural health monitoring systems. In this article, a novel phase change material (PCM)-TEG system of integrating PCM with TEG for improving the output performance was reported. The proposed system was almost adiabatic with the external environment, which effectively avoided heat exchange with the internal environment of the aircraft. High-performance paraffin/expanded graphite (EG) composite PCM was fabricated by a simple melting-adsorption approach.Because of the porous structure and high thermal conductivity of EG, significant enhancement in the thermal conductivity of the composite was observed, while there was little decrease in the latent heat capacity. A variety of typical experimental conditions were designed by aero-thermal calculation method that based on the actual service environment of aircraft. The output performance of the TEG and thermal transfer properties of the composite were investigated systematically, which showed that the existence of PCM increased the temperature difference between the two sides of the TEG and effectively promoted its energy conversion potential. Finally, the performance for the PCM-TEG system was also compared under different experimental conditions. The study provides a solution for obtaining electrical power source, which is highly desired in wireless structural health monitoring systems.

In this paper, quantitative experiments were made to measure the concentration of key intermediate products (CO, NO, and NO) and the gas temperature for combustion flow based on near-infrared and mid-infrared laser absorption spectroscopy. This paper used the developed diagnostic system to study two main ignition modes of a real 1-Newton thruster based on ammonium dinitramide (ADN): steady-state firing and pulse-mode firing over a feed pressure of 5-12 bar. The steady-state firing experiments distinguished the whole process into catalytic decomposition stage and combustion stage, experimentally demonstrating the combustion kinetics mechanism of an ADN monopropellant. Experiments for pulse-mode firing showed the measured multispecies concentration and temperature were consistent with pulse trains, verifying good performance for the thruster pulse-mode firing operation. The performance of the thruster was given based on the optical measurements, and characteristic velocity for the ADN-based thruster standard operation was higher than the corresponding 1-Newton hydrazine thruster.

Precise prediction of aerothermal loads is significantly limited by the unclear interactions between the thermal protection system surface and the surrounding high-enthalpy gas. To address this, we propose an optical diagnostic method based on optical emission spectroscopy and laser absorption spectroscopy to investigate the gas-surface interactions within the boundary layer. Experiments are conducted in an air plasma flow produced by the 1.2 MW inductively coupled plasma wind tunnel at the China Academy of Aerospace Aerodynamics with enthalpy of 20 MJ/kg and heating time of 100 s. The cylindrical samples made of pure silicon carbide are tested, and quartz samples with the same exposed geometry are tested in parallel as a reference material. The optical emission spectroscopy system has four spectrometers to cover the wide wavelength range 200-1100nm, providing qualitative, spatially-, and spectrally- resolved measurements of the multi-species radiative emission adjacent to the sample surface. Laser absorption spectroscopy is deployed at different axial locations to quantify the number density and translational temperature of OI (3s5S) with a 500 Hz scanning rate and 200 kHz acquisition rate. Additionally, the surface temperature of each sample is detected by an infrared pyrometer. Scanning electron microscopy and energy dispersive spectrometry are performed before and after the plasma heating. Our measurement results provide valuable information on surface reaction pathways and catalytic recombination effects on atomic oxygen number density distributions. Finally, these self-consistent results show that the proposed method is reliable to deeply investigate gas-surface interactions within boundary layer in harsh aerothermal environment.

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