First , the direction of fringe variation in the interference images is different with different intake duct , but in the same intake duct , the direction is the same . second , different intake duct has different rules to flow variation . third , the infinite width of interference fringe is visual , high precision , and easy to qualitative analysis , but the finite width of interference fringe is easy to judge the direction of fringe variation and to further detailed analysis 实验结果表明,气道不同,条纹的变化方向不同,但同一气道在不同的流量下,条纹的变化方向是一致的;不同形状的气道对流量的敏感程度不同,对气体旋流的扩散作用影响也有很大的差异;用无限宽条纹法得到的图像直观,灵敏度大,易于做定性的分析对比,而有限宽条纹法可以进行流体在运动方向的判别,更有利于详细的分析研究。
On the basis of practically achieved low - frequency laser - vibration measuring - system , this thesis analyses the principle of laser - vibration measuring - system , the optical factors which have effect on contrast degree of interference fringe , the optical - electric transformation factors which have effect on measuring accuracy , the important of filter for improving the accuracy in the absolute calibration and the outward vibration which has effect on system accuracy , etc . in chapter one , the background of laser measuring vibration , and then followed by its current status , is introduced and analyzed 本论文根据实际研制的激光测振仪系统,从提高激光测振仪精度的角度出发介绍了激光测振仪的原理,并详细地剖析了光路对测振仪干涉条纹对比度的影响、光电转换对测量精度的影响、光电信号的滤波放大以及外界振动对测振仪系统的影响等技术问题。
In chapter three , the importance of maintaining the equal optical path between measuring beam and reference beam in measuring horizontal and vertical vibration table are analyzed , and the factors having effect on contrast degree of interference fringe are introduced . for improving the accuracy of laser - vibration - measuring - system , the phase - modulation - multi - period - average method and the vibration isolated of system are analyzed 第三章分析了光路设计中的等光程问题的重要性,以及影响干涉条纹对比度的相关因素;并从提高测量精度的角度分析了调相多周期平均法和系统的隔振。
We build a close vibration compensation system which can successfully achieve the measurement of interference fringes movement and - vibration compensation . it puts forward pre - setting fill - in pulses method to implement phase shifting with the same pzt . with this new method , the interference fringe can be stabilized at any pre - setting phase position 提出了填充脉冲数预设定的方法,可以将干涉条纹锁定在任意设定的位相位置,实现了用pzt同时实现振动补偿和移相测量;深入分析讨论了pzt的延迟问题,创造性地提出了用多次逼近补偿的办法,给出了反馈补偿的算法,解决了补偿过程中存在的系统不稳定和过补偿的问题。
A useful technique has been provided and developed for the researching and analyzing the factors and variation of flow field in the intake duct of diesel engine . to find out a new method to measure flow measurement , different intake duct on different conditions are experimented and researched by real - time holographic interferometry . real - time holography interferometry has many characteristics , such as high precision , non - destructive , high contrast of interference fringes and full field test 该方法具有精度高、非接触、条纹对比度好、对被测物体形状和表面无特殊要求的特点,实验了对三维非定常流动过程的可视化实时采集,为了解和分析不同流量、不同结构参数下进气道内气流运动状态和流动特性的变化关系及其影响因素提供了一种有效的测试手段。