Quasi-Detonation in Porous Medium

Specific characteristics of the quasi-detonation process in hydrogenous mixtures were reported in an experiment with H2 + O2 combustion (0 = 0.4-1.6) carried out in a 124-mm diameter tube, 1,830-mm long, the tube was stuffed with steel or ceramic spheres of 19 and 38 mm diameters. 

Some of the data obtained in the tube stuffed with 19-mm diameter steel spheres [12,18] are presented in Fig. 5.11. Curves 1, 2, 3 and 4 denote the process velocity at initial pressures of Fo = 0.1,0.2,0.5 and 0.9 MPa, curves 5,6,7 and 8 are relative pressure amplitude Pi/Po at the same Pq values. Obstacles installed in the tube do not interrupt the detonation process when the initial pressure is 0.5 MPa, however the velocity and the pressure of the process is slightly lower that those in the unobstructed tube. It is typical, in the obstructed tube, that the detonation pressure is independent of mixture composition over a wide range. 

A weak, practically unnoticeable, effect of the obstacles thermal characteristics on the detonation velocity is a special feature of the experiments [12,18]. When the tube is stuffed with ceramic or steel spheres, the cooling of blast products changes, but the detonation process does not change. This means that the heat loss in the reaction zone is negligible in comparison with the friction loss. 

The trend of the decreasing influence of the friction loss on the detonation velocity with increasing initial pressure was observed in the experiments [18]. Due to the large sizes of spheres stuffing the tube and their high permeability, the detonation velocity was close to the detonation velocity in the unencumbered tube. 

Detailed investigation of HAM combustion regimes in an encumbered tube with a 50-mm diameter was performed in [21]. Some data for combustion regimes of nitrogen + hydrogen + oxygen mixtures in rough wall ducts can be found in [22]. 

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