| Boundary condition is one of the vital factors which affect the ignition and propagation chracteristics of detonation. The present study systmatically studied the ignition and propagation characteristics of detonation influenced by porous suction wall, by means of theorical analysis, numerical simulation as well as experiments. Besides, pre- ignition phenomenon in detonation is investigated, which is often encountered in detonation propulsion engines,the main achievement are as follows:The detonation of H2/Air mixture affected by porous suction wall are studied by means of numerical simulation. From the results, there exit two aspects of effects on detonation: on one hand, part of flow filed is sucked into suction chamber, colliding with the porous wall, with a series of arc shocks formed. The interaction of arc shocks and tranverse waves leads to the attenuation of tranvers waves and even failure of detonation; O n the other hand, there are a series of hot spots formed during the collision between flow filed and porous wall,which, to some extent,will promote the detonation,especially in the critical state.Different activity,hole diameter and distance are investigated, while the boundary conditions and initial state remain the same. Numerical simulaiton of propagation of detonation were conducted, from which conclusion can be drawn as follows: with the decrease of the activity of mixture, 3 modes of propagation are investigated: self-sustained mode, critical mode and failure mode, mechanism of which are expounded, especially galloping mechanism is elucidated in detail.Study on detonation chracteristics influenced by preignition under porous wall is conducted in the experiments as well as nume rical simulaiton. Study on mixture of different activity and different diameter of holes shows that pre-ignition will destroy the structure of detonation,which is different from porous wall suction, and which should always be avoided in detonation propulsion engine. |
