Since the wind wave model Simulating Waves Nearshore （SWAN） cannot effectively simulate the wave fields near the lateral boundaries, the change characteristics and the distortion ranges of calculated wave factors in...Since the wind wave model Simulating Waves Nearshore （SWAN） cannot effectively simulate the wave fields near the lateral boundaries, the change characteristics and the distortion ranges of calculated wave factors including wave heights, periods, directions, and lengths near the lateral boundaries of calculation domain are carefully studied in the case of different water depths and wind speeds respectively. The calculation results show that the effects of the variety of water depth and wind speed on the modeled different wave factors near the lateral boundaries are different. In the case of a certain wind speed, the greater the water depth is, the greater the distortion range is. In the case of a certain water depth, the distortion ranges defined by the relative errors of wave heights, periods, and lengths are different from those defined by the absolute errors of the corresponding wave factors. Moreover, the distortion ranges defined by the relative errors decrease with the increase of wind speed; whereas the distortion ranges defined by the absolute errors change a little with the variety of wind speed. The distortion range of wave direction decreases with the increase of wind speed. The calculated wave factors near the lateral boundaries with the SWAN model in the actual physical areas, such as Lake Taihu and Lake Dianshan considered in this study, are indeed distorted if the calculation domains are not enlarged on the basis of actual physical areas. Therefore, when SWAN is employed to calculate the wind wave fields near the shorelines of sea or inland lakes, the appropriate approaches must be adopted to reduce the calculation errors.展开更多
运用模态声传递向量(MATV)方法预测现有高速列车车体铝型材在白噪声激励下的振动声辐射特性,分别对比阻尼损耗因子和铝型材结构截面三角形倾角对其振动声辐射的影响。结果显示现有高速列车车体铝型材结构在较宽频带范围内的声辐射效率...运用模态声传递向量(MATV)方法预测现有高速列车车体铝型材在白噪声激励下的振动声辐射特性,分别对比阻尼损耗因子和铝型材结构截面三角形倾角对其振动声辐射的影响。结果显示现有高速列车车体铝型材结构在较宽频带范围内的声辐射效率随频率的提高整体呈上升趋势,最后基本趋近于1。240 Hz以下声辐射效率曲线呈近似线性递增的关系,240 Hz以上声辐射效率由于高阶模态的影响处于波动状态。铝型材阻尼损耗因子的增加可以减少铝型材结构向外辐射的噪声,阻尼损耗因子从0增加到1%,总声功率级急剧降低了约33.5 d B,随着阻尼损耗因子从3%增加到7%,总声功率级近似线性减小且降低速度放缓。铝型材截面三角形倾角越小,铝型材结构的声辐射效率越小,其辐射噪声的能力越弱,倾角从60°变化到30°,总声功率级降低了约27.9 d B。展开更多
基金The National Natural Science Foundation of China under contract No.51079082the Natural Science Foundation of Shanghai City under contract No.14ZR1419600+1 种基金the Research Innovation Projects of 2013 Shanghai Postgraduate under contract No.20131129the Top Discipline Project of Shanghai Municipal Education Commission
文摘Since the wind wave model Simulating Waves Nearshore （SWAN） cannot effectively simulate the wave fields near the lateral boundaries, the change characteristics and the distortion ranges of calculated wave factors including wave heights, periods, directions, and lengths near the lateral boundaries of calculation domain are carefully studied in the case of different water depths and wind speeds respectively. The calculation results show that the effects of the variety of water depth and wind speed on the modeled different wave factors near the lateral boundaries are different. In the case of a certain wind speed, the greater the water depth is, the greater the distortion range is. In the case of a certain water depth, the distortion ranges defined by the relative errors of wave heights, periods, and lengths are different from those defined by the absolute errors of the corresponding wave factors. Moreover, the distortion ranges defined by the relative errors decrease with the increase of wind speed; whereas the distortion ranges defined by the absolute errors change a little with the variety of wind speed. The distortion range of wave direction decreases with the increase of wind speed. The calculated wave factors near the lateral boundaries with the SWAN model in the actual physical areas, such as Lake Taihu and Lake Dianshan considered in this study, are indeed distorted if the calculation domains are not enlarged on the basis of actual physical areas. Therefore, when SWAN is employed to calculate the wind wave fields near the shorelines of sea or inland lakes, the appropriate approaches must be adopted to reduce the calculation errors.
文摘运用模态声传递向量(MATV)方法预测现有高速列车车体铝型材在白噪声激励下的振动声辐射特性,分别对比阻尼损耗因子和铝型材结构截面三角形倾角对其振动声辐射的影响。结果显示现有高速列车车体铝型材结构在较宽频带范围内的声辐射效率随频率的提高整体呈上升趋势,最后基本趋近于1。240 Hz以下声辐射效率曲线呈近似线性递增的关系,240 Hz以上声辐射效率由于高阶模态的影响处于波动状态。铝型材阻尼损耗因子的增加可以减少铝型材结构向外辐射的噪声,阻尼损耗因子从0增加到1%,总声功率级急剧降低了约33.5 d B,随着阻尼损耗因子从3%增加到7%,总声功率级近似线性减小且降低速度放缓。铝型材截面三角形倾角越小,铝型材结构的声辐射效率越小,其辐射噪声的能力越弱,倾角从60°变化到30°,总声功率级降低了约27.9 d B。
