Rocket plume

Liu, J. B., J. Yampolsky, P. Ronney, and M. A. Gundersen. 2000. Plasma-enhanced combustion for reduction of rocket plume soot. 13th ONR Propulsion Meeting Proceedings. Eds. G. Roy and P. Strykowski. Minneapolis, MN. 

Miller, E., and S. Mitson. 1985. The suppression of afterburning in solid rocket plumes by potassium salts. AlAA Paper No. 85-1253. 

Fig.l2.n Definition of the primary flame and the secondary flame of a rocket plume. 

Fig. 12.11 shows the structure of a rocket plume generated downstream of a rocket nozzle. The plume consists of a primary flame and a secondary flame.Fil The primary flame is generated by the exhaust combustion gas from the rocket motor without any effect of the ambient atmosphere. The primary flame is composed of oblique shock waves and expansion waves as a result of interaction with the ambient pressure. The structure is dependent on the expansion ratio of the nozzle, as described in Appendix C. Therefore, no diffusional mixing with ambient air occurs in the primary flame. The secondary flame is generated by mixing of the exhaust gas from the nozzle with the ambient air. The dimensions of the secondary flame are dependent not only on the combustion gas expelled from the exhaust nozzle, but also on the expansion ratio of the nozzle. A nitropolymer propellant composed of nc(0-466), ng(0-369), dep(0104), ec(0 029), and pbst(0.032) is used as a reference propellant to determine the effect of plume suppression. The burning rate characteristics of the propellants are shown in Fig. 6-31. Since the nitropolymer propellant is fuel-rich, the exhaust gas forms a combustible gaseous mixture with the ambient air. This gaseous mixture is ignited and afterburning occurs somewhat downstream of the nozzle exit. The major combustion products in the combustion chamber are CO, Hj, CO2, N2, and HjO. The fuel components are CO and H2, the mole fractions of which at the nozzle throat are co(0.47) and iH2(0.24).

Fig. 12.12 Flame photographs of rocket plumes, showing that the dimensions of the secondary flame decrease with increasing concentrations of KNO,.

Syage, J. A., and M. N. Ross, An Assessment of the Total Ozone Mapping Spectrometer for Measuring Ozone Levels in a Solid Rocket Plume, Geophys. Res. Lett., 23, 3227-3230 (1996). Symonds, R. B W. I. Rose, and M. H. Reed, Contribution of Cl-and F-Bearing Gases to the Atmosphere by Volcanoes, Nature, 334, 415-418 (1988). 

The challenge of predicting the plume radiance is describing the thermodynamic combustion process within the rocket chamber, the plume structure and the rocket plume chemical composition. The factors guiding these processes are the rocket motor design parameters, as well as the rocket motor fuel chemistry. In addition, environmental conditions have a significant impact on the plume structure and the plume chemical composition. 

In addition, the modelling problem is considered in terms of a forward mapping, i.e. prediction of the emission spectra of the rockets from their design parameters, as well as a reverse mapping, where the rocket design parameters are predicted from the middle-IR spectral absorbances of the rocket plume. 

Military space-based sensors have been deployed for more than 4 decades to provide surveillance, reconnaissance, and tracking of space-borne targets such as infrared airborne missiles, rocket plume signatures during launch, midcourse correction, and terminal phases. Military communications satellites are generally designed to provide covert communications between the various assets, such as fighter aircraft, support aircraft, naval vessels, aircraft carriers, and army divisions. 

Particulate carbon is a major reaction product of metal-fluorocarbon flames and mainly determines its spectral characteristics [7]. The influence of soot on the optical properties of rocket plumes has been reviewed in Ref. [19]. 

As the shuttle increased its upward velocity, it flew past the emerging and expanding smoke puffs. The last smoke was seen above the field joint at 2.733 seconds. At 3.375 seconds the last smoke was visible below the solid rocket boosters and became indiscernible as it mixed with rocket plumes and sm-rounding atmosphere. 

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