高温过滤器用脉冲反吹喷嘴出口流场特性分析

Characterization of Flow Field in the Exit of Pulse Jet Nozzle for High-temperature Filtrating

在常温工况下,以直管、渐缩和缩放三种结构形式的脉冲反吹喷嘴为研究对象,利用高速摄影系统拍摄了喷嘴脉冲反吹过程中的分幅阴影照,利用计算流体力学软件FLUENT对这一过程进行了数值计算,试验结果与计算结果吻合很好,验证了计算模型计算喷嘴反吹时刻非定常流场的可靠性。在此基础上,对高温工况下的脉冲反吹流场进行计算研究,结果表明,高温工况下,脉冲反吹过程中,喷嘴出口流场中存在压力振荡,该振荡在脉冲反吹流场传播;喷嘴的结构形式对喷嘴出口流场的压力均一化波系具有重要影响,缩放式喷嘴出口射流核心区最大。通过跟踪流场不同时刻的压力分布发现,三种结构形式喷嘴出口流场的射流核心区均可观察到由膨胀波、反射斜激波、剪切层组成的激波胞格结构。

The numerical calculation of the procedure of pulse cleaning under normal temperature condition is performed by using the computational fluid dynamics software FLUENT. The calculation is compared with the framing shadow photographs of the procedure taken by the high speed photography system. The test result agrees well with the simulation result, which proves the reliability of calculating model. Calculation research of pulse cleaning flow field is carried out under high temperature condition. The result shows that there is pressure oscillation in nozzle outlet. The pressure oscillation spreads in pulse cleaning flow field. The structure of nozzle has important effect on the outlet flow field, especially at jet core of laval nozzle outlet. Through tracing of pressure distribution of flow field at different times, it is found that there is shock wave cell structure composed of expansion wave, reflection oblique shock wave, shear layer at outlet jet core area of nozzle in the three structures.