Rocket Propulsion Elements, 9th Edition

CHAPTER 20ROCKET EXHAUST PLUMES

This chapter is an introduction to rocket exhaust plumes providing a general background, description of various plume phenomena and their effects, and references for further study. The plume consists of moving hot exhaust gases (often with entrained small particles) issuing from rocket nozzles. Such gas formations are not uniform in structure, velocity, or composition. They contain several different flow regions with supersonic shock waves. Plumes are usually visible as a brilliant flame, emitting intense radiation energy in the infrared, visible, and ultraviolet, and are a strong noise source. Many plumes leave trails of smoke or vapor and some contain toxic gases. At high altitudes, plume gases spread over large regions, and some portion of the plume can flow backwards outside of the nozzle and reach components of the flight vehicle.

Plume characteristics (size, shape, structure, emission intensities of photons and/or sound pressure waves, visibility, electrical interference, and/or smokiness) depend not only on the characteristics of the particular rocket propulsion system and its propellants but also on the flight path, flight velocity, altitude, local weather conditions (such as wind, humidity, and/or clouds), and vehicle configuration. See Refs. 20–1 to 20–3. In recent decades, progress has been made in understanding the complex interacting physical, chemical, optical, aerodynamic, and combustion phenomena within plumes by means of laboratory ...