中文摘要：

为考察转捩射流中拟序结构的空间演化过程及其对不同Stokes颗粒扩散的影响，采用有限容积方法和分步投影算法对三维气固两相射流进行了直接模拟。其中流体控制方程组的时间积分采用低存储三阶精度的Runge-Kutta格式；颗粒的跟踪在拉格朗日框架下进行。模拟结果发现，在流场拟序结构由大尺度转化为小尺度的过程中，中、小Stokes数的颗粒能自发地调整它们的扩散方式，分别由非均匀状态向均匀状态以及由均匀状态向非均匀状态转变。

英文摘要：

To investigate the spatial evolution of coherent structures and its effects on particle dispersion at different Stokes numbers in transitional jets, the finite volume method and fractional-step projection schemes were used to directly simulate a three-dimensional gas-solid two-phase jet. The governing equations of the fluid were integrated in time by the low-storage, third-order Runge-Kutta scheme. The particles were traced in the Lagrangian reference frame. It is observed that the particles at some Stokes numbers can spontaneously adjust their dispersion patterns during the transition of coherent structures from large-scale to small-scale. For particles at the smaller Stokes numbers, the dispersion changes from uniform pattern to non-uniform pattern. But for particles at the intermediate Stokes numbers, the dispersion changes from non-uniform pattern to uniform pattern.