Influence of Different Altitudes on the Solid Rocket Contrail Formation in the Near Field

Detecting the infrared characteristics of the contrails is a reasonable approach to tracing the rocket, and the particle properties of the contrails are the basis of the infrared analysis. The conventional numerical approach to obtaining the particle properties is a Euler/Lagrange method or a simple Euler/Euler method, difficultly obtaining more accurate results because it ignores the particle size distribution in parcels or cells. A modified Euler/Euler method is applied to simulate the contrail formation in the near field of a solid rocket motor at different altitudes, which considers the size distribution by adding the first- to second-order particle radius moments based on the simple Euler/Euler method. The simulation results show that the crystals are generated at altitudes from 10 km to 20 km and that the contrails are visible at altitudes from 10 km to 15 km, where the radii of the crystals are from 0.1 & mu;m to 0.3 & mu;m. The visible contrails indicate that aviation vehicles are cruising at altitudes from 10 km to 15 km, and the smaller crystals indicate that the contrails are generated by rockets, not aircraft. Our work can provide important insight for the follow-up infrared analysis of the contrails based on the obtained particle radii.