Geometry rocket propellants

Experimental Determination of the Burning Rate. Experimental determinations of the burning rate are made with the closed tomb for gun propellants and the strand burner for rocket propellants. The closed bomb is essentially a heavy-wahed cylinder capable of withstanding pressures to 689 MPa (100,000 psi). It is equipped with a piezoelectric pressure gauge and the associated apparatus requited to measure the total chamber pressure, which is directly related to the force of the propellant. It also measures the rate of pressure rise as a function of pressure which can then be related to the linear burning rate of the propellant via its geometry. Other devices, such as the Dynagun and the Hi—Low bomb, have also been developed for the measurement of gun propellant performance. 

Figure 8.2 Examples of the geometrie stmeture of a rocket propellant for (a) short and (b) long range missUes.

Mullis (M10), Bastress (B4), and Carlson and Seader (Cl) have conducted experimental studies to determine the heat-transfer characteristics of typical rocket-exhaust igniters. In these studies, the total rate of heat transfer to the propellant or simulated propellant surface was measured as a function of mass flow rate, geometry, and impingement angle between the igniter exhaust... 

Figure 1. Schematic of a solid-propellant rocket motor with a star-shaped geometry.

The constant-pressure bomb is a very suitable tool for the determination and the comparison of the combustion rates of different propellants. However, the combustion rate as a function of the pressure may also be determined using a small test rocket motor. The motor s diameter may be between 50 and 100 mm. The combustion pressure is varied inside the motor by varying a nozzle throat area. The influence of the geometry of the propellant grain occasionally may be significant, resulting in no good correlation between the combustion rate determined in a constant-pressure bomb and that in a test rocket motor. 

In reference 31, the bulk burn and Forest Fire model was applied to two-dimensional rocket motor geometries with regions of damaged lower density propellant between the case and the main propellant bed. 

Nanometre-thick polyaniline films were used in the fabrication of chemiresistors, with a highly accessible surface geometry that enhanced ammonia and nitrogen dioxide gas adsorption and promoted surface reaction/interaction." Conducting polymers in chemiresistor sensors for sensing hazardous hypergolic liquid propellant vapours and toxic exhaust plume acidic vapours of solid rocket motors (nitrogen oxides, hydrazines and toxic HCl vapours) at explosive, toxic and threshold limit value cmicentration levels have been reviewed." ... 

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