Electronic counter/velocity probes

The measuring system that uses an electronic counter/velocity probes technique is schematically represented in Figure 4.9. 

Figure 4.9. Functional diagram of the system for the determination of the detonation velocity using the electronic counter/velocity probes technique...

The moving of the flame front may be followed using the ionisation probes (or other types of velocity probes)/electronic counter (or oscilloscope) technique. Optical and electrooptical methods may be used as well. 

The determination of the combustion rate using ionisation probes and an electronic counter resembles the determination of the detonation velocity. The same principle is applied in both cases. The main difference lies in the different values of the measured time interval In the detonation, the time interval is on the microsecond scale, while in combustion the time interval is of seconds or tenths of seconds. 

Determination of the Detonation Velocity Using Electronic Counter and Velocity Probes Technique... 

A short time interval needed by the detonation wave to travel a known distance between two velocity probes (or pins) through the explosive is determined by an electronic counter. Thus, the detonation velocity is obtained as a ratio between the distance traveled and the corresponding time interval. 

The arrival of the shock wave is registered with suitable probes placed at a certain distance from each other and at a definite distance from the explosive charge. The time interval needed for the shock wave to pass the distance between two probes is registered by an electronic counter or an oscilloscope. The shock wave velocity at a measured distance from the explosive charge is calculated as a ratio of distance to time. 

The treatment of the data resembles the detonation velocity determination when ionisation probes and an electronic counter or an oscilloscope are used (Subsections 4.1,3 and 4.1.4). 

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