Mr. Ligong Zhang Profile

Ligong Zhang

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Proceedings Article | 6 November 2023 Paper

Analysis of scattering characteristics of ablation particles

Ligong Zhang, Lu Bai, Yin Li

Proceedings Volume 12921, 129211J (2023) https://doi.org/10.1117/12.2688440

KEYWORDS: Ablation, Particles, Mie scattering, Lithium

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The study of hypersonic aircraft and their tail flames is an important area of research in the field of aerodynamics. The tail flame of such aircraft is an important characteristic, as it affects the aerodynamic stability of the aircraft and has implications for the safety and efficiency of flight. In order to accurately simulate the tail flame and calculate its spectral radiation characteristics, it is necessary to analyze the scattering characteristics of the ablative particles in detail. This involves studying the changes in optical properties that occur as a result of variations in the proportion of mixed ablation products, specifically B₂O3 and SiO₂, during the early stages of the reaction. The paper under consideration focuses on the analysis of this process, with particular attention given to the properties of the new modified material ZrB2-SiC. The researchers used MIE scattering theory combined with independent scattering approximation to compare and analyze the process. Their findings indicate that the extinction coefficient decreases with the increase of ablation time during this early transition stage, while the difference in scattering image function is not significant. Therefore, it is suggested that the difference of scattering phase function can be ignored in future studies. The phase function of SiO₂ particles is directly taken as the final result. This study is of great significance for the development of more accurate simulation models of flame in the tail of hypersonic aircraft, as it emphasizes the need for a detailed understanding of the scattering properties of ablative particles. By analyzing the optical properties of these particles, we can better understand the situation of tail flame and predict its spectral radiation characteristics more accurately. This information can be used to improve the safety and efficiency of hypersonic aircraft and may have wider applications in the field of aerodynamics.

Proceedings Article | 15 December 2022 Paper

Study on scattering characteristics of zirconia ablated particles

Ligong Zhang, Lu Bai, Xiaolin Sun

Proceedings Volume 12478, 124782U (2022) https://doi.org/10.1117/12.2654782

KEYWORDS: Scattering, Particles, Zirconium dioxide, Atmospheric particles, Refractive index, Combustion, Flame, Solids, Lutetium, Infrared radiation

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The infrared radiation characteristics of aircraft engine plume are of great significance for aircraft detection and identification. At present, with the requirements of engine combustion chamber environment, some new coating materials came into being. This material will produce a large number of gaseous and solid ablation particles in the reaction process, so the emission and scattering of ablation particles must be considered in the calculation of plume infrared radiation transfer. Based on the refractive index data of ZrO2 particles given in the literature, the scattering phase function, scattering cross section, albedo and asymmetry factor of ZrO2 particles are calculated by T matrix. The scattering phase function of ablative particles at different wavelengths and the change of scattering characteristics of ablative particles with the passage of reaction time are analyzed. The results show that the scattering effect is obvious when the wavelength is short. With the increase of combustion time, the forward scattering of clusters increases sharply, and the scattering at all angles is more obvious. Therefore, it is necessary to accurately calculate the scattering characteristics of ablation particles in order to accurately calculate the radiation characteristics of aircraft plume in the future.

Proceedings Article | 15 December 2022 Paper

Effects of cirrus clouds on atmospheric background radiation and transmittance

Xiaolin Sun, Lu Bai, Ligong Zhang

Proceedings Volume 12478, 1247838 (2022) https://doi.org/10.1117/12.2654815

KEYWORDS: Clouds, Transmittance, Atmospheric sensing, Atmospheric particles, Scattering, Particles, Mie scattering, Atmospheric physics, Atmospheric sciences

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Based on atmospheric background radiation, the radiation transfer equation is derived and solved by discrete coordinate method. The atmospheric background radiance and atmospheric transmittance are calculated in visible light, short-wave infrared and near-infrared bands (0.4 to 2.5μm) under space-based satellite detection and ground-based observation modes respectively, and the influence of cloud distribution on atmospheric background radiance is summarized and analyzed. The results show that the influence of clouds on atmospheric transmittance is related to zenith Angle under ground-based detection conditions, and the influence of cirrus clouds on atmospheric transmittance increases gradually with the increase of zenith Angle under most bands.

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