Plume suppressant

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).

Potassium salts are known to act as suppressants of spontaneous igmtion of hydrocarbon flames arising from interdiffusion with ambient air. It has been reported that potassium salts act to retard the chemical reaction in the flames of nitropolymer propellants. Two types of potassium salts used as plume suppressants are potassium mtrate (KNO3) and potassium sulfate (K2SO4). The concentration of the salts is varied to determine their region of effectiveness as plume suppressants. 

Fig. 12.17 shows a typical set of afterburning flame photographs obtained when a nitropolymer propellant without a plume suppressant is burned in a combustion chamber and the combustion products are expelled through an exhaust nozzle into the ambient air. The physical shape of the luminous flame is altered significantly by variation of the expansion ratio of the nozzle. The temperature of the combustion products at the nozzle exit decreases and the flow velocity at the nozzle exit increases with increasing e at constant chamber pressure. 

High efficiency candle type filter after absorbers 0.1-2 pm droplets <50 <0.03 - Increased energy consumption - Production loss - Capacity loss - Plume suppression... 

Plume suppression Difiicult Difficult Fair Fair Easy Easy... 

The saltwater, low-buoyancy system has a tendency to become laminar as the ceiling jet propagates away from the plume due to the buoyancy suppressing the turbulence. 

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

Jensen Webb (Ref 43) examined the data predicting the extent of afterburning in fuel-rich exhausts of metal-modified double-base proplnt rocket motors so as to determine the amt of an individual metal which is required to suppress this afterburning. The investigatory means they used consisted of a series of computer codes. First, an equilibrium chemistry code to calculate conditions at the nozzle throat then a nonequilibrium code to derive nozzle plane exit compn, temp and velocity and, finally, a plume prediction code which incorporates fully coupled turbulent kinetic energy boundary-layer and nonequilibrium chemical reaction mechanisms. Used for all the code calcns were the theoretical environment of a static 300 N (67-lb) thrust std research motor operating at a chamber press of S.SMNm 2 (500psi), with expansion thru a conical nozzle to atm press and a mass flow rate... 

Similar experiments have been conducted in which insect damage or mating suppression have been demonstrated with other insect species. Table IV shows that 7.5 gram a.i./acre was highly effective in suppressing mating of the artichoke plume moth. 

The dominant transport mechanism for both aerosol and gaseous agents in the atmosphere is advection associated with the bulk motion of the atmosphere. Since airflows in the planetary boundary layer exhibit signihcant turbulence under most conditions (though turbulence may be suppressed under conditions of temperature inversion), this will cause aerosol releases to disperse into a plume or puff that expands... 

Physical models of the mantle suggest plumes are impossible because of the high pressures at depth which suppresses the buoyancy of the material and prevents the formation of narrow plumes. 

The 12-pallet classification test results consider the number of opened sprinklers, maximum steel beam temperature at the ceiling, maximum plume temperature and velocity, maximum heat flux, maximum weight loss rate, and net percentage weight loss. The classification of a given aerosol product is based upon suppression or control of the fire and the number of sprinklers that opened during the fire test. An aerosol product is considered a Level 1 if the fire was well controlled or suppressed, a Level 2 if the fire was well to marginally well controlled or a Level 3 if the fire was not well controlled. 

Reduction of combustion-generated noise from high-speed jet flows is the topic discussed in Section 2. Fundamental research and novel noise-reduction techniques are presented. These include detailed experimental and computational studies of jet-plume noise, as well as precise measurements. A narrow-band acoustic database generated from actual aircraft landing practice is used as a benchmark for the development of the effective noise-suppression technology. 

Fig. 4.5 Bidirectional communication in predator-prey systems mediated by chemosensation. Foraging crabs locate bivalves by homing in on the metabolites contained in the plume created by the excurrent flow (top). Chemical cues are released by foraging crabs, as well as by injured bivalves (middle). These cues suppress the response of other bivalves, and which makes them undetectable to downstream predators (bottom). Drawing courtesy to Jorge Andres Varela Ramos...

From the point of view of the present book, some understanding of the mechanism(s) underlying MALDI is important because of effects of ionization suppression (and possibly enhancement, though the latter has not been widely observed in MALDI) that must be taken into account if MALDI is to be used for quantitation an extended discussion of suppression and enhancement effects is given in Section 5.3.6a for the case of electrospray ionization. MALDI suppression effects have been extensively investigated (Knochenmuss 1996,1998, 2000, 2003) and correlated with the detailed theory of in-plume reactions controlled largely by thermochemical considerations. Examples of the suppression of matrix ions by relatively large amounts of analyte are shown in... 

A notable and perhaps unexpected observation (Figure 5.6) is that, when matrix suppression occurs, all matrix ions are suppressed, e.g., an analyte that appears in the spectrum as the protonated molecule can suppress matrix alkah ion adducts [Ma-F Na] as well as protonated matrix [Ma-FH]+. This observation has been interpreted (Knochenmuss 2000) in terms of quantitative considerations of secondary plume reactions among matrix ion species that can be interconverted by reactions with neutral matrix. These reactions are sufficienily close to isoenergetic that they should proceed rapidly under plume conditions, so that when a highly efficient matrix-analyte reaction depletes one matrix species (e.g. [Ma-FH]+), all others (e.g., [Ma-FNa]+) wiU also be efficiently depleted via this interconversion reaction channel. 

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