Numerical Investigaton of Sand Erosion Phenomena in Rotor/Stator Interaction of Jet Engine Compressor

沙粒冲刷是固体颗粒撞击墙体，对墙体表面造成严重的机械破坏的现象。众所周知，各种机械，如飞机、船舶、燃气轮机、水泵等，都会因沙粒侵蚀而严重降低性能和寿命。这种现象是典型的气固两相湍流，是一个流场、颗粒运动轨迹和壁面变形相互作用的多物理问题。然而，传统的数值模拟方法并没有考虑冲蚀过程中流场和颗粒运动轨迹的变化。这种治疗在身体上是不现实的。为此，我们开发了沙蚀现象的数值计算程序，包括流场和壁面形状的时间变化。在本研究中，我开发了一个程序来模拟轴流压气机转子/静子相互作用中的沙蚀现象，以阐明其物理特性及其对气动性能的影响。2006年，我扩展了现有的旋转参照系程序，以计算转子/静子相互作用。然后将该规范应用于发生沙蚀的正方形截面的90度弯道。将数值计算结果与实验数据进行对比，验证了所开发的程序能够较好地再现湍流和冲蚀表面的时间变化。2007年，该程序被应用于轴流压气机的动静干扰问题，以阐明其物理意义。通过对数值计算结果的分析，证实了第一次冲击对转子前缘的冲蚀最为严重，而在转子尾缘尖端由于离心力的作用使大量颗粒向该区域移动，冲蚀相对较严重。

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. It is well-known that the performance and lifetime of various machines, such as airplane, ship, gas turbine, pump and so on, are severely degraded due to sand erosion. This phenomenon is E typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with among others. However, the change of the flow field and the relating particle trajectory during the erosion process have not been taken into account by conventional simulations. This treatment is physically unrealistic. Hence, we have developed the numerical procedure for sand erosion phenomenon, including the temporal change of the flow field and the wall shape. In the present research, I developed a code to simulate sand erosion phenomena in a rotor/stator interaction of an axial compressor, in order to clarify the physics and the effects on the aerodynamic performance.In 2006, I extended our existing code for rotational frame of reference to compute a rotor/stator interaction. Then the code was applied to a 90-degree bend with a square cross-section in which sand erosion took place. Comparing the numerical results with the experimental data, it was confirmed that the developed code can reproduce the temporal changes of the turbulent flow and eroded surface satisfactorily.In 2007, the code was applied to a rotor/stator interaction problem of an axial compressor, to clarify the physics. Investigating the numerical results, it was confirmed that the first impact leads to the most severe erosion around the rotor leading edge, and relatively severe erosion occurs around the tip of the rotor trailing edge, because centrifugal force makes a number of particles go towards the region.