2013 1(12)

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   Long abstract

 

Pages:

73 - 76

Language:

RU

Ref.:

3


 


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2013_1(12)_13.pdf

 

 

EXPERIMENTAL STUDY OF HEAT FLUX FROM THE SHOCK-COMPRESSED AND REACTIVE MEDIA AT THE CONTACT SURFACE.

Gulevich M.A., Pay V.V., Yakovlev I.V., Pinaev A.V.

Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia


Keywords:

ignition and explosion sensors, planar thermocouple, heat flux, gas mixture detonation


Existing measures to prevent unauthorized dynamic development of explosion in coal mines, such as oil shale and water barriers, automatic explosion suppressing system - localization of explosions and others due to the low speed of operation have poor efficiency. Their belated response does not allow for a timely inserting or inhibition of the atmosphere, the required volume of excavation. One reason for this delay is low reliability or a substantial inertia sensors of this phenomenon for the transmission of operational information about what happened to the phenomenon of timely management of the process of forming explosion suppression barrier. In this paper, we consider the possibility of using a thermopile of planar as a fast-response thermocouple gages of ignition and explosion.

Combustion and gas mixtures in a detonation channels accompanied by a significant rise in temperature, and as a result, intense heat exchange with the hot reaction product in contact with these walls. The proposed method of investigation of heat flux on the walls of the channel under these conditions involves the use of planar thermocouples, which are based on the use of the Seebeck effect.

Considered in detail the thermal and electromagnetic processes in planar thermocouples when pulse heating the reaction products of gas mixtures. The experimental data obtained by such thermocouples in the detonation mixture 2O2 + N2 + CH4 in a metal tube of 70 mm diameter, at an initial pressure - 0.2, 0.4 bar and during fast propagation of combustion in a pipe 1800 mm, in methane-air mixtures at atmospheric pressure to a volume of methane concentration 9.3 - 9.8%. Conditions of these experiments are close to actual mine conditions.

Delivered experiments showed that the thermopile of planar thermocouples allow you to uniquely identify the nature propagating in the channel of the process, since the density of heat flow in the shock-compressed mixture is almost an order of magnitude lower than for the subsequent wave of rapid combustion. In this case, the flux density in the zone of rapid combustion, in turn, on the order of magnitude less than the detonation wave. Representing sources - energy converters of constant readiness, such thermopile can be used as sensors registration ignition and detonation of mines in hazardous gas and dust. The characteristic time of the formation of thermopile electrical pulse is ~ 1 ms, which allows you to use it as a starting signal for the start of fire extinguishing systems with the response time of ~ 100 ms.

 

 
     

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