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Analysis of Finite Amplitude Wave Motion in Acoustic Compressor using a Duct with Varying Cross-Section.

使用变截面管道的声学压缩机中的有限振幅波动分析。

基本信息

批准号：
09650178
负责人：
KAWAHASHI Masaaki
金额：
$ 2.11万
依托单位：
SAITAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650178/
关键词：
Acoustic Standing Wave Finite Amplitude Wave Acoustic Compressor

项目摘要

First, the results of numerical analysis are described. On finite amplitude wave motion of the air column in a closed tube with cross sectional area contraction for the acoustic compressor which is driven by a piston oscillating sinusoidally, the numerical analysis based on explicit Mac-Cormack method with second order accuracy in time and fourth order accuracy in space was applied, and the detailed analysis within cross section reduction ratio 1 - 100 was carried out. Especially, boundary condition based on valve operating condition considering the acoustic compressor real operation in exhaust and intake processes was newly set in this analysis. And also in the wall friction term, not only steady term based on the instantaneous flow velocity but unsteady friction term was considered. From the analytical result, following fact clarified. Though the compression ratio at the closed end of the tube increases with the increase in the cross section reduction ratio, under cross section reduc … More tion ratio of 16, the propagating shock wave is appeared, and it suppresses the increasing rate in compression ratio with increase of the piston amplitude. The shockless resonance is obtained in the wide range of the piston amplitude, when the cross section reduction ratio increases, and the compression ratio also increases. But the effect of the cross section reduction ratio is not remarkable over 50. In the numerical analysis introduced boundary condition based on actual motion of valves, the instability of wave phenomenon appeared. It shows that improvement of further boundary condition is required.Next, the experimental verification result is described. In this experiment, an axisymmetric acoustic tube (cross section reduction ratio 100) in which cross section is exponentially reduced and a tube in which cross section is constant cross section were used. The air column in these tubes was excited using the piston driven by the electromagnetic accelerator in die resonance point vicinity. And the wave motions were measured. By raising the rigidity of the whole system, the improvement in the measurement accuracy was attempted it. In addition, the accuracy of the piston displacement measurement was improved by the introduction of high-precise displacement gage. The results obtained show that the pressure fluctuation in the tube with constant cross section was closely coincident with calculated result in the amplitude and in the wave form at the closed end of the tube. However, the experimental results for the tube with cross section reduction was not coincident with the calculated results, and it shows that the improvement of numerical analysis in the case with large reduction ratio of cross section is required. Less

首先，数值分析的结果进行了说明。针对活塞正弦振动驱动的声压缩机，采用时间上二阶精度、空间上四阶精度的显式Mac-Cormack方法，对截面收缩率为1 ~ 100的封闭管内空气柱的有限振幅波动进行了数值分析.特别是，在分析中，新的边界条件，阀的工作条件，考虑到声学压缩机的真实的运行在排气和进气过程中。在壁面摩阻项中，不仅考虑了基于瞬时流速的定常项，而且考虑了非定常摩阻项。根据分析结果，澄清了以下事实。虽然截面收缩率的增大使圆管封闭端的压缩比增大，但在截面收缩率为100%时， ...更多信息当压缩比为16时，出现了传播激波，并抑制了压缩比随活塞振幅的增大而增大的速率。在活塞振幅较大的范围内，截面收缩率增大，压缩比增大，均能产生无激波共振。但断面收缩率的影响在50以上并不显著。在数值分析中根据阀门的实际运动引入边界条件，出现了波动现象的不稳定性。结果表明，边界条件还需进一步改进，并给出了实验验证结果。在该实验中，使用了横截面指数减小的轴对称声管（横截面减小率100）和横截面为恒定横截面的管。在谐振点附近，利用电磁加速器驱动活塞激励管内空气柱。并测量了波动。通过提高整个系统的刚度，尝试提高测量精度，并引入高精度位移计，提高了活塞位移的测量精度。计算结果表明，等截面管内压力脉动的幅值和封闭端的波形与计算结果基本一致。但是，对于截面收缩率较大的圆管，实验结果与计算结果并不一致，这表明在大截面收缩率情况下，数值分析方法还有待改进。少