Rocket engine exhaust plume produces a strong infrared radiation signal and is widely used for target diagnosis and detection. The traditional method for calculating the infrared radiation characteristics of the exhaust plume is difficult and time-consuming. In this paper, the engineering analytical method in the band is used to calculate the equivalent spectral radiation intensity of the exhaust plume, and the spectral radiation intensity varies with the viewing angle. The relationship curve constructs the spectral radiance intensity as a function of the viewing angle. This method does not just take advantage of the efficiency of the engineering analysis method, but also preserves the accuracy of numerical simulation. The spatial distribution of the infrared radiation intensity field in the typical band of the exhaust plume is simulated by an example.
Exhaust plume flow field have the characteristics of high temperature, high speed and multi-species flow. Exhaust plume infrared signal are important basis of diagnosing, detecting and identifying plume spectrum. This paper focuses on the infrared radiation characteristics of high-altitude plume. The plume flows exhausted from a micro-nozzle of a low-thrust engine at high-altitude have been simulated numerically through using a DSMC method. Both the properties of plume flow at high altitude and the non-equilibrium effect related to rarefied gases are analyzed. Results are given numerically in good agreement with high-altitude plume observations. With the fields of pressure, temperature and main components of the exhaust plume as input data, the line-by line method was used to calculate the 2~5μm infrared spectral radiation properties of the plume. Different flight conditions are considered to analyze the influence on the infrared radiation characteristics. Some interesting conclusion are finally achieved.
Aerodynamic heating is one of important factors affecting hypersonic aircraft design. The Direct Simulation Monte Carlo method (DSMC) has evolved years into a powerful numerical technique for the computation of complex, non-equilibrium gas flows. In atmospheric target, non-equilibrium conditions occur at high altitude and in regions of flow fields with small length scales. In this paper, the theoretical basis of the DSMC technique is discussed. In addition, the methods used in DSMC are described for simulation of high temperature, real gas effects and gas-surface interactions. Combined with the solution of heat transfer in material, heat-flux distribution and temperature distribution of the different shape structures was calculated in rarefied conditions.