适用于高温阻抗管的修正传递函数法

Modified Transfer Function Method for High Temperature Impedance Tube

为预测高温阻抗管中能否产生平面波进而使用传递函数法计算材料的吸声系数,对自制高温阻抗管内空气的温度场进行了数值仿真,利用仿真得到的温度场建立了阻抗管内声场分布的仿真模型;根据求解结果,将材料前端面至较远传声器之间的空气温度梯度近似为只有轴向温度梯度,求出了轴向温度梯度时的平面波解析解,进而对传递函数法进行了修正。通过某种多孔材料的吸声系数的仿真结果,验证了修正算法的正确性。修正与未修正算法的结果比较表明,当材料前端空气的轴向温度梯度较小时,其对吸声系数计算的影响可以忽略,从而扩宽了高温阻抗管的设计空间。

To predict plane wave propagating in high temperature impedance tube and to calculate sound absorption coefficient with transfer function method, temperature field simulation is performed for impedance tube made in our own laboratory. Then sound pressure field is modeled according to the achieved temperature field. The air temperature gradient between the front face of the material and the distant microphone in the impedance tube is assumed to exist axially, thus the transfer function method can be used and the modified analytic formula is obtained and verified by the simulation. It is found that the impact of temperature gradient on the calculated absorption coefficient can be ignored in the case of small axial temperature gradient. This study may facilitate the design of high temperature impedance tube.