Jensen Carl, Raspet Richard
Department of Physics and Astronomy, National Center for Physical Acoustics, University of Mississippi, University, Mississippi 38677, USA.
J Acoust Soc Am. 2010 Jun;127(6):3470-84. doi: 10.1121/1.3425735.
The thermoacoustic properties of fibrous materials are studied using a computational fluid simulation as a test of proposed analytical models for propagation in porous materials with an ambient temperature gradient. The acoustic properties of porous materials have been understood in terms of microstructural models that approximate the material as an array of pores with empirical shape factors used to fit the pore theory to the material. An extension of these theories of acoustics to the thermoacoustic case with an ambient temperature gradient has been proposed by Roh et al. [J. Acoust. Soc. Am. 121, 1413-1422 (2007)] and a model based on Wilson's relaxation approximation for porous acoustics [J. Acoust. Soc. Am. 94, 1136-1145 (1993)] is proposed herein, but the predictions of these analytical models have not been tested successfully against measurements. Accurately characterizing the effects of the applied temperature gradient in a wide bandwidth laboratory setup have proven difficult; as a result, the authors conducted a numerical simulation of propagation within a fibrous geometry in order to test the predictions of the analytical models. The results for several fibrous samples show that the models yield a reliable prediction of thermoacoustic performance from the shape factors and relaxation times.
利用计算流体模拟研究纤维材料的热声特性，以此来检验所提出的用于在具有环境温度梯度的多孔材料中传播的分析模型。多孔材料的声学特性已根据微观结构模型来理解，这些模型将材料近似为一系列孔隙，并使用经验形状因子将孔隙理论与材料相拟合。Roh等人[《美国声学学会杂志》121, 1413 - 1422 (2007)]提出了将这些声学理论扩展到具有环境温度梯度的热声情况，本文提出了一种基于威尔逊多孔声学弛豫近似[《美国声学学会杂志》94, 1136 - 1145 (1993)]的模型，但这些分析模型的预测尚未成功地与测量结果进行对比检验。事实证明，在宽带实验室装置中精确表征所施加温度梯度的影响很困难；因此，作者对纤维几何结构内的传播进行了数值模拟，以检验分析模型的预测。几个纤维样品的结果表明，这些模型能根据形状因子和弛豫时间对热声性能给出可靠的预测。
