Fuel-rich gaseous products

The air-intake used to induce air from the flight-altitude atmosphere plays an important role in determining the overall efficiency of ducted rockets. The air pressure built up by the shock wave determines the pressure in the ramburner. The temperature of the compressed air is also increased by the heating effect of the shock wave. The fuel-rich gaseous products formed in the gas generator burn with the pressurized and shock-wave heated air in the ramburner. The nozzle attached to the rear-end of the ramburner increases the flow velocity of the combustion products through an adiabatic expansion process. This adiabatic expansion process is equivalent to the expansion process of a rocket nozzle described in Section 1.2. 

Demirbas, A., Karshoglu, S., and Ayas, A. (1996). Hydrogen Resources Conversion of Black Liquor to Hydrogen Rich Gaseous Products, Fuel Science and Technology International 14(3). pp. 451-463. 

When AP particles are added to GAP-AN pyrolants, a number of luminous flame-lets are formed above the burning surface. These flamelets are produced as a result of diffusional mixing between the oxidizer-rich gaseous decomposition products of the AP particles and the fuel-rich gaseous decomposition products of the GAP-AN pyrolants. Thus, the temperature profile in the gas phase increases irregularly due to the formation of non-homogeneous diffusional flamelets. 

These two processes (i.e., devolatilization and char oxidation) may take place simultaneously, especially at very high heating rates. If devolatilization takes place in an oxidizing environment (e.g., air), then the fuel-rich gaseous and tar products react further in the gas phase to produce high temperatures in the vicinity of the coal particles. 

The first reactor is a gasification (or fast pyrolysis) reactor in which PVC-rich waste is converted at 700-900 °C with steam into a gaseous product (fuel gas and HCl) and residual tar. 

MPa. A reddish flame is seen above the bluish flame. On the other hand, no bluish and reddish flames are seen when the p(0.80) propellant burns at a pressure of 0.1 MPa, as shown in Fig. 7.4 (c). The flame is entirely yellowish, which can be ascribed to the fuel-rich nature of the diffusion flame generated by the gaseous decomposihon products of the binder and the AP parhcles.l Indeed, the flame... 

When large spherical AP particles dg = 3 mm) are added, large flamelets are formed in the dark zone.Pl Close inspection of the AP particles at the burning surface reveals that a transparent bluish flame of low luminosity is formed above each AP particle. These are ammonia/perchloric acid flames, the products of which are oxidizer-rich, as are also observed for AP composite propellants at low pressures, as shown in Fig. 7.5. The bluish flame is generated a short distance from the AP particle and has a temperature of up to 1300 K. Surrounding the bluish flame, a yellowish luminous flame stream is formed. This yellowish flame is produced by in-terdiffusion of the gaseous decomposition products of the AP and the double-base matrix. Since the decomposition gas of the base matrix is fuel-rich and the temperature in the dark zone is about 1500 K, the interdiffusion of the products of the AP and the matrix shifts the relative amounts towards the stoichiometric ratio, resulting in increased reaction rate and flame temperature. The flame structure of an AP-CMDB propellant is illustrated in Fig. 8.1. 

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).

The principal infrared emissions from gaseous combustion products of propellants are caused by the high-temperature COj and H2O molecules. When nitropolymer propellants or AP composite propellants burn, large amounts of high-temperature CO2 and HjO molecules are formed. If these propellants burn incompletely due to their fuel-rich composihons, large amounts of hydrocarbon fragments and solid... 

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