Unlike conventional pneumatic tires, the nonpneumatic tires (NPT) are explosion proof and simple to maintain and provide low rolling resistance. At high vehicle speeds, however, the complex airflow produced by the open flexible-spoke structure of NPT yields high aerodynamic noise, which contributes to sound pollution in the vehicular traffic environment. Inspired by the idea that a nonsmooth riblet structure can affect fluid flow and offer noise reduction, the analyses of the effect of the nonsmooth riblet surface on the aerodynamic noise of an NPT and noise reduction mechanism were presented in this paper. First, computational fluid dynamics (CFD) was used to analyze the surface pressure coefficient characteristics of a smooth flexible-spoke tire rolling at a speed of 80 km/h and subsequently validating the numerical simulation results by comparing them with published test results. Secondly, large eddy simulation (LES) and the Ffowcs Williams–Hawkings (FW-H) method were, respectively, used to determine the transient flow and far-field aerodynamic noise. Then, the mechanism of noise reduction was investigated using a vortex theory. Based on the vortex theory, the positions and strengths of noise sources were determined using the Lamb vector. Finally, according to the fluid boundary layer theory, a nonsmooth riblet surface was arranged on the surface of the spokes, and the influences of the riblet structure parameters, including size, position, and direction, on aerodynamic noise were analyzed. Based on the vortex theory, it was found that the nonsmooth riblet structure can reduce the Lamb vector, suppress the generation of flow vortices, decrease acoustic source strength, and effectively decrease noise up to 5.18 dB using the optimized riblet structure. The study results provide a theoretical basis for the structural design of a new low-noise NPT.

中文翻译：

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用非光滑的Riblet表面降低非充气轮胎气动噪声的数值研究

与传统的充气轮胎不同，非充气轮胎（NPT）防爆且易于维护，滚动阻力低。然而，在高车速下，由NPT的开放式弹性辐条结构产生的复杂气流会产生高的空气动力学噪声，从而加剧了车辆交通环境中的声音污染。受到不光滑的肋状结构可以影响流体流动并降低噪声的想法的启发，本文对不光滑的肋状结构表面对NPT气动噪声的影响进行了分析，并提出了降噪机理。第一，计算流体动力学（CFD）用于分析以80 km / h的速度滚动的柔韧轮辐轮胎的表面压力系数特性，然后通过将其与公开的测试结果进行比较来验证数值模拟结果。其次，分别使用大涡模拟（LES）和Ffowcs Williams-Hawkings（FW-H）方法来确定瞬态流量和远场气动噪声。然后，利用涡旋理论研究了降噪的机理。基于涡旋理论，使用兰姆向量确定噪声源的位置和强度。最后，根据流体边界层理论，在辐条表面布置了一个不光滑的肋状表面，肋状结构参数的影响包括大小，位置，和方向，对空气动力噪声进行了分析。基于涡旋理论，发现非光滑的肋状结构可以使用优化的肋状结构减少Lamb向量，抑制流动涡流的产生，降低声源强度，并有效地将噪音降低至5.18 dB。研究结果为新型低噪声NPT的结构设计提供了理论依据。