Studies of Detonation Quenching by Water Sprays

Methods designed to quench a detonation wave in a pipe usually rely on some passive device which often presents an unacceptable impedance to the normal pipe flow. One method which overcomes this problem is a triggered water spray barrier, the principles of which are examined in the present study. Experimental data on detonation quenching were obtained in a vertical tube, 76 mm diameter, fitted with various spray generators. The empirical relations of Ranger and Nicholls were then used to calculate the rate at which water is stripped from a droplet in the shock flow field to form a micromist, thus enabling the energy loss from the wavefront in heating and vapourising the micromist to be found. Application of the Shchelkin criterion to the quenching mechanism shows that a 20% energy loss is required from the wavefront. This requirement is met at distances ranging from 0.2 to 1.0 cell lengths which is in reasonable agreement with the expected position of the CJ plane.