中文摘要：

应用计算流体动力学理论和仿生设计方法，模仿雪花的分形结构，在高速列车车厢表面设计了Koch雪花表面织构，探求其对降低高速列车车体表面空气摩擦噪声的影响。采用非结构化混合网格和RNG k-ε模型求解可压缩N-S方程，基于宽频噪声源模型求解空气摩擦噪声分布。计算结果表明：在Koch雪花织构内部产生二次涡，大大降低了空气与高速列车表面的空气摩擦噪声。为了进一步探求表面织构对高速列车降噪的影响，设计了由两种不同尺度的Koch雪花基元交叉排列组成的确定性多尺度表面织构和由Koch雪花基元与圆坑基元交叉布置形成的确定性复合表面织构。结果表明，确定性多尺度表面织构的降噪效果要优于单一织构，而确定性复合表面织构的降噪效果不如单一表面织构中降噪效果较好的那种。

英文摘要：

In order to reduce the air frictional noise at the air-carriage interface of high speed train, a Koch type snowflake surface structure is designed to simulate the fractal structure of snowflake and analyzed with the theory of computational fluid dynamics （CFD） and the method of bionic design for the surface of high speed train. The compressible N-S equation is solved using unstructured hybrid grid and k - ε model and the noise distribution is solved based on broadband noise source. Simulation results demonstrate that the air frictional noise is greatly reduced because of the secondary vortex generated in the Koch snowflake like surface structure. A kind of multi scale surface structure consists of Koch snowflake cells on two scales and a sort of compound surface texture combining cells of Koch snowflake and circular dents are designed in order to further explore the influence of surface texture on the decrease of the noise of high speed train; that multi scale surface texture is better than single .texture but compound surface texture is worse than the better one of the single texture in reduction of the air frictional noise, which provide an effective guidance for the study of reducing the air frictional noise of high speed train.