Burning rate radiation effects

In an effort to account for this effect, Spalding and Johnson have considered the effect of radiation losses from the solid surface. Johnson has also included a provision for a volume rate of energy loss, but he does not state the basis for the term. In the case of surface pyrolysis, the resulting equations predict the relations of burning-rate versus pressure as shown in Fig. 16. 

The overall radiation fraction, XT, is 0.15. Compute the initial burning rate, now including radiation effects. Show all your work and clearly indicate any assumptions. 

A pool of PMMA with a diameter of 1 m burns in air. Radiation effects are to be included. In addition to using the properties from Problem 9.1, let XT = 0.25,7f = 1500 K and k = 0.5 nC1. If it is known that the critical mass loss rate for PMMA is 4 g/m2 s, calculate the flux of water (m") needed to extinguish this fire. If instead the oxygen is reduced, at what mass fraction will extinction occur ... 

Burning Rates of Plastics The Small B Assumption and Radiation Effects... 

PATR 1637(1947XBurning and other characteristics of stick rocket proplnts) 6)S.S.Penner, JApplPhys 19, 392-8(1948) CA 42, 6512(1948)(Effect of radiation on rate of burning of solid fuel rocket proplnts) 7)L.H.Eriksen, Investigation of Asphalt-Perchlorate and Resin-Perchlorate Rocket Propellants , PATR 1676(1948) 8)S.S.Penner, JApplPhys 19, 511-13(1948) CA 42, 8475(1948) (The theory that burning rates of rocket proplnts increase slightly with an increase in radiation path length was verified experimentally for two double-base rocket proplnts) 9)W.G.Thummel,... 

Additional work was performed by Gardner (Refs 92 99) on proplnts for future missions in space. A PBAA AP/Al proplnt, an aluminized double-base proplnt, and a polyurethane—AP/Al proplnt were studied as a function of Co radiation, with a dose rate of 2.54 x 10 R/hr and total doses ranging up to 1.5 x 10 R. The effects were noted on tests with the burning rate, tensile stress, elongation modules and hardness of the three materials. The PBAA proplnt withstood 1.5 X lO R. On the tensile strength, the double base and polyurethane decrease significantly at a dose of 4 x 10 R. On elongation, the double base decreased on stress at max strain after 10 R, while the polyurethane pro-pint decreased on modulus and hardness after a dose of 10 R. Estimates of the radiation effects on polymers are listed in Table 19... 

The maximum velocity at the axis is twice the average, whereas the velocity at the wall is zero. The effect of the burner wall is to cool the flame locally and decrease the burning velocity of the mixture. This results in flame stabilization. However, if the heat-transfer processes (conduction, convection, and radiation) involved in cooling the flame are somehow impeded, the rate of heat loss is decreased and the local reduction in burning velocity may no longer take place. This could result in upstream propagation of the flame. 

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