Insulation Of High Temperature Erosion Conditions Of Dense Gas Dynamic Ablation Study

As the maneuverability of SRM advance and the using of complex grain, particles in the combustion production has more probability to aggregate highly in local position of combustor, resulting in high-temperature and dense two-phase flow. The erosion rate of insulator of SRM will increase remarkably when it was impinged by this dense two-phase flow, this will do harm to SRM' operation. Such is the problem that required to be settled urgently in high-velocity and high-acceleration SRM investigation. The dissertation presented the study on the process of insulator eroded by particles, the result not only advanced our understanding of the property of insulator ablation but provided some help to create a model of ablation about insulator undergoing particles impinging also. The content of this thesis can be divided into three parts:1) A real-time measurement method for insulator erosion was developed by utilizing x-ray real-time radiography technique (RTR) and experimental instrument was designed. A replaceable adjustor has been used which makes it possible to change particle concentration and impacting velocity. Special fitting make this method can also be used to soft specimen's experiment besides hard specimen. According to the characteristic of the RTR image a method of image processing was developed by using MATLAB which is suitable for research of ablation.2) The instantaneous erosion rate of the insulator eroded by highly concentrated particles was measured using this method and erosion rate of different kinds of specimen when impinged by different particle concentration and impacting velocity has been studied. A series of insulator recession dynamic images have been obtained in the process of experiment. Analyzing these images can be found that at different time the position of most serious erosion is changed along the sample's length direction and which is parallel to the particles impacted direction, and the shape of the concave pit has relation to the kind of the material. Within the impact velocity range adopted in the experiment the impact velocity of particles is the main influence factor on erosion of insulation, while the contribution of particle concentration is relatively small. The instantaneous erosion rate and the mean erosion rate versus time were acquired by images processing. These results provide experimental proofs to study mechanism of insulation erosion.3) Numerical simulation of the process of insulator erosion was conducted by using charring ablation code. As the change of the erosion zone grid was produced automatically and at some position grid was refined. According to the shape of the ablator surface theparticle concentration and angle versus time was obtained through projection which can then be used to calculate the critical thickness of char layer. According to this thickness whether or not char layer been ablated is decided. The evolutionary process of the concave was simulated successfully by the numerical calculating, and the trend is in agreement with experiment. However, the calculating precision needs to be promoted.