高温环境下梯度多孔金属纤维的吸声性能及优化设计

摘要

为了研究高温环境下具有梯度结构的多孔金属纤维吸声性能,应用物性参数与温度之间的关系式,将Johnson-Allard吸声理论模型拓展到高温条件下,建立了多孔金属纤维材料高温吸声理论模型.采用高温阻抗管设备,测量了多孔材料试件,实验测试数据与理论计算结果符合很好,验证了理论模型的有效性.应用声阻抗转移公式,进一步将该理论模型拓展为梯度多孔金属纤维的高温吸声理论模型,并结合优化算法对多层梯度材料结构进行了优化设计.研究结果表明:高温条件下,材料吸声效果相比常温条件下稍差;多孔材料孔隙率和纤维丝径对材料吸声性能影响显著,随着孔隙率或纤维丝直径增大,材料吸声系数在低频段减小,在中频段增大;经过结构优化设计后,在同等条件下,多层梯度金属纤维材料吸声性能明显优于单层结构,具有良好的吸声效果.研究工作对多孔金属纤维材料的高温吸声应用及梯度优化设计具有一定的指导意义.%To characterize the sound absorbing properties of gradient porous metal fibers at high temperature,a theoretical model is developed by introducing the temperature-dependent parameters of air into the Johnson-Allard model.This model is favorably validated by experiments on porous metal fibers at high temperatures.Further,employing acoustic impedance transfer formulation,another theoretical model for multi-layered gradient metal fibers at high temperature is established.By adopting an optimization strategy,the multi-layered gradient metal fibers are optimized for superior sound absorption.The results reveal that the sound absorbing capacity of the material at high temperature is slightly worse than that in normal temperature.With the increase of porosity or fiber diameter,the sound absorption decreases in low frequency range but increases in medium frequency range.The sound absorption capability of the gradient structure is better than that of homogeneous structure with the same thickness,and the optimal sound absorption can be achieved in given specific conditions.This research is helpful for the application and design of the gradient porous metal fibers in high temperature environments.