阶梯复合形光声池声-流特性计算与评估

为了提高光声池的检测性能,提出并分析了一种阶梯复合形光声池。以传统圆柱共振型光声池为基准模型,通过对比解析与模拟计算结果,验证了所采用模拟方法的可靠性,基于模拟方法求解并获得了阶梯腔半径、阶梯腔长度和阶梯腔数量对阶梯复合形光声池声-流特性的影响规律。结果表明:减小阶梯复合形光声池中阶梯腔半径,光声信号相对增强,阶梯腔长度存在最佳尺寸使得光声信号达到最强,阶梯腔数目应选1为宜;流场方面,阶梯复合形光声池构型特征改善了腔内气体涡漩回流的情况,若进一步对其腔内过渡处进行圆角或倒角处理,腔内流速梯度将变得更为平稳。选择一组设计参数进行构型与计算,得到阶梯复合形光声池腔体容积降低为对应圆柱共振型光声池的39.7%,光声信号相对提升约18.7%,同时其频响带宽变窄,品质因数相对得到提升,整体结果显示阶梯复合形光声池声-流特性要优于对应的圆柱共振型光声池。研究内容可为光声光谱光声池的结构优化与改进提供参考。

Calculation and Evaluation of Acoustic and Flow Field Characteristics of Trapezoid Compound Photoacoustic Cell

To improve the detection performance of the photoacoustic cell,a trapezoid compound photoacoustic cell is proposed and analyzed.Taking the traditional cylindrical resonant photoacoustic cell as the reference model,the reliability of the simulation method is verified by comparing the results of analysis and simulation.Based on the simulation method,the influence of the radius,length,and the number of the stepped cavity on the acoustic field and flow field characteristics of the trapezoidal composite photoacoustic cell is calculated.The results show that reducing the stepped cavity radius of the trapezoidal compound photoacoustic cell can enhance the photoacoustic signal,and the optimal length of the stepped cavity can make the photoacoustic signal to be the strongest,and the number of the stepped cavity should be one.In terms of the flow field,the configuration characteristics of the trapezoidal composite photoacoustic cell improve the condition of gas vortex return to the cavity.If the transition to the cavity is furthering rounded or chamfered,the velocity gradient in the cavity will become more stable.Select a set of design parameters,the calculation results show that the volume of the trapezoid compound photoacoustic cell cavity is reduced to 39.7%of the corresponding cylindrical resonant photoacoustic cell,and the photoacoustic signal is increased by about 18.7%.In addition,its frequency response bandwidth is narrowed,and its quality factor is improved.The overall results show that the acoustic field and flow field characteristics of the trapezoidal composite photoacoustic cell are better than that of the corresponding cylindrical resonant photoacoustic cell.The research content can provide reference for the structural optimization and improvement of the photoacoustic spectral photoacoustic cell.