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Acta Aeronautica et Astronautica Sinica ›› 2024, Vol. 45 ›› Issue (24): 630568.doi: 10.7527/S1000-6893.2024.30568

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Altitude-scaling law for multi-band radiation signals from liquid-propellant rocket engine exhaust plumes

Yiqiang SUN1, Tanxiao ZHU1, Qinglin NIU2, Zhihong HE1, Shikui DONG1()   

  1. 1.Key Laboratory of Aerospace Thermophysics of Ministry of Industry and Information Technology,Harbin Institute of Technology,Harbin 150001,China
    2.College of Mechatronic Engineering,North University of China,Taiyuan 030051,China
  • Received:2024-04-22 Revised:2024-05-25 Accepted:2024-06-25 Online:2024-12-25 Published:2024-07-08
  • Contact: Shikui DONG E-mail:dongsk@hit.edu.cn
  • Supported by:
    National Natural Science Foundation of China(U22B2045)

Abstract:

The relationship between the intensity of single-band infrared radiation from rocket motor plumes and flight altitude is often non-monotonic in actual detections. The issue of multivalence occurs in height inversion. This paper focuses on analyzing many typical liquid propellant rocket engine plumes. Computational Fluid Dynamics(CFD)is used to determine the temperature, pressure, and component information of the reactive flow field of the plume. The Light-on-Sight(LOS)method and the NASA-SP-3080 high-temperature gas radiative property database are employed to calculate the intrinsic infrared radiation signals of the plume. Additionally, the Modtran program is used to determine the atmospheric transmittance at altitudes ranging from 11 to 61 km in both top-down and horizontal observations. Subsequently, the apparent radiation signals of the rocket engine plume are computed. On the basis of the element composition of the liquid propellant and the mechanism of gas radiation generation, it is proposed to construct a dimensionless characteristic parameter based on the multi-band apparent radiance, the so-called Relative Second Order Difference(RSOD), as the characterization parameter of the altitude-scaling law of the plume infrared radiation. The monotonous mapping relationship between the RSOD and the flight altitude is obtained analytically. It is found that the monotonic correlation between the radiative signatures constructed through the quadratic construction of multi-band radiated signals and the flight altitude can be obtained, and it is verified by different thrusts that the relationship is universal to a certain extent. Then, using this monotonic relation, better inversion altitude results can be obtained, and the inversion accuracy is higher in the range of 31-61 km. Finally, it is found that the RSOD differentiation is better for different engine propellant types, and it is speculated that the use of RSOD information as a characteristic quantity can be beneficial to differentiating engine types.

Key words: liquid-propellant rocket engine exhaust plume, apparent infrared radiation, multi-band, Relative Second Order Difference (RSOD), altitude-scaling law

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