R. Meyer J. Köhler A. Homburg Explosives

Gas Generators
Gas Generators
gaserzeugende Ladungen; charges génératrices de gaz
Pyrotechnic or propellant device in which propellant is burned to
produce a sustained flow of gas at a given pressure on demand. Gasgenerating
units are employed in blasting operations conducted in
mines without recourse to brisant explosives. The device consists of a
non-detonating gas-generating material and a priming or a heating
charge, which are confined together in a steel pipe. The heating
charge evaporates the gas-generating substance such as liquid CO2
(W Cardox); another possibility is for the primer to initiate an exothermal
chemical reaction (Chemecol process, Hydrox process). The
gas-generating reaction may be the decomposition of nitrogen-rich
compounds such as ammonium nitrate, or nitrate mixtures, or nitroguanidine
in the presence of carbon carriers and sometimes in the
presence of catalysts. When a given pressure has been reached, a
bursting disc releases the gases in the pipe. The sudden gas expansion
taking place in the borehole has an effect similar to that of an
explosion.
Gas Jet Velocity
Nozzle Velocity; Ausströmgeschwindigkeit; vélocité à jet de gaz
In rocket technology, the velocity of the combustion gases discharged
from the combustion chamber and passing the nozzle into the atmosphere.
The jet velocity and the mass flow serve to calculate the
W Thrust. The jet velocity will increase with the pressure in the combustion
chamber, i.e., with the expansion ratio under passage through
the W Nozzle. The pressure in the combustion chamber should not be
adjusted too high, otherwise the wall thickness of the chamber (i.e. its
weight) will become too great (W Mass Ratio).
In accordance with the Saint-Venant and Wantzel formula
where:
P0 is the gas pressure at the nozzle exit (atmospheric pressure);
P1 is the pressure in the combustion chamber;
k is the coefficient of specific heat;
R is the ideal gas constant measured in absolute units;
T is the flame temperature in Kelvin, and
M is the mean molecular weight of the combustion gases.
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