AN EXPERIMENTAL INVESTIGATION OF A GAS-PARTICLE SYSTEM
CALIFORNIA INST OF TECHNOLOGY PASADENA JET PROPULSION LAB
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The presence of particles in the gas flow through rocket nozzles results in appreciable performance degradation, which tends to cancel the increased performance that results from high combustion temperatures of propellants with metal additives. The higher the particle weight fraction, the lower the efficiency delivered Isptheoretical Isp. In addition, theoretical investigations indicate that performance losses increase appreciably with increased particle sizes. The presence of very small particles is least detrimental as they cause the least reduction in performance due to the fact that these particles have a high aerodynamic drag-to-mass ratio and thus high acceleration and velocity. Small particles have velocities and temperatures through-out the nozzle that are almost equal to those of the gas however, the gas velocity itself may be somewhat reduced by the small particles. Results of extensive experimental investigations and the effect of pertinent parameters on particle size distribution, particle shape, and combustion efficiency are discussed. With aluminized propellants, it is shown that particle size distribution is pressure-dependent. An empirical relationship giving the average particle diameter D on a volume basis as a function of the pressure P is developed, which is written as log P equals a bD.
- Physical Chemistry