Temperature coefficient burning

TEGN = triethyleneglycoldinitrate 346 temperature coefficient -> burning rate 45... 

The temperature coefficient of motor chamber pressure, irK, has been reported (17) to be about 0.09%/°F. in the static firing of small motors loaded with 2-in. diameter tubular grains (inside-outside burning). Measured specific impulse was reported to be 90% of theoretical. Higher percentages of theoretical specific impulse are obtained in larger motors. 

The properties of this proplnt are it remains rubberlike at -40°F and does not flow at+140°F its specific impulse is 170sec at lOOOpsi optimum expansion density l,81g/cm3 an exponent of 0.70 in the burning law burning rate 0.72 in/sec at lOOOpsi 70°F, and a restriction ratio of 182 under the same conditions. The temperature coefficient of pressure, thrust, burning time at constant restriction ratio is 0.6% per °C (Ref 1, pp 101 -02)... 

Effect of Varying Both the Zinc Stearate and Barium Chromate Content on the Burning Rate and Temperature Coefficient of a Tungsten Delay Composition... 

If the gases flow continously out, as in the case of a rocket motor, the pressure remains almost constant throughout the combustion period. The linear burning rate and its variation with the temperature and pressure may be determined in a Crawford Bomb. The temperature coefficient of the burning rate is the variation per degree of temperature increase at constant pressure. The dependance on pressure is characterized by the pressure exponent (see above). 

The general characteristics of these groups of powder are summarized in Tables 118-120, according to Roth and Capener [ J ]. Potassium salts arc added (Tables IIS and 119) as flash reducing agents. Lead salts (Table 119) are decomposition moderators which play a role in producing low temperature coefficients of burning propellants and a low exponent n in the expression... 

Temperature coefficient— The relative change of Some measurable quantity (e.g. burning time per unit length) with change of temperature, mostly expressed as mean change per degree in percent of mean temperature within a certain range. 

For standard fuel, the temperature coefficient is a constant -1 x 10 k/°C (about the same as the positive coefficient in pool water). (Therefore, the ISOTHERMAL temperature coefficient is near zero.) Because of the different mechanisms in FLIP fuel, the temperature coefficient becomes more negative as temperature increases (see Figure 3) but averages about -1 x 10" k/ C from 0-700°C. Note also that the temperature coefficient will become smaller as the core burns out (the Er goes away). 

The temperature dependence of a dielectric constant is quite complex, and it may increase or decrease with temperature depending upon the material (see Section 12.2.4). In general, however, a material below its freezing point exhibits lowered dielectric constant and dielectric loss. Above freezing the situation is not clear-cut, and since moisture and temperature are important to both drying and dielectric properties, it is important to understand the functional relationships in materials to be dried. Wood, for example, has a positive temperature coefficient at low moisture content [5] that is, its dielectric loss increases with temperature. This may lead to runaway heating, which in turn will cause the wood to burn internally if heating continues once the wood is dried. 

A fuel composition can be eliminated or modified if any of the performance characteristics are deficient. For example, the plutonium mass loading should meet a minimum quantity per rod to burn for the desired cycle length at a specified average pin power. In addition, the net temperature coefficient must be negative and burnable poisons should bum at rates comparable to the plutonium. 

Burning rate, mm min Coefficient of linear thermal expansion, 10 °C Deflection temperature under 29 6-30 20-50 15-33 45-56... 

Slow burn-out tends to be associated with high-quality burn-out conditions and to produce a not unduly excessive wall-temperature rise. In fact, there appears to be an extreme condition in which the temperature rise may hardly be noticeable, and it becomes difficult to say whether burn-out has occurred. These circumstances probably coincide with the jump discontinuity in Fig. 3 ceasing to exist for certain values of system parameters. The condition is effectively one in which, at the burn-out point, the heat-transfer coefficient is the same whether the surface is vapor-blanketed or liquid-wetted. 

---