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激光多普勒流速仪(LDV)具有准确度高、非接触测量、动态响应快等优点,在流速测量中得到了广泛应用。条纹的非一致性是影响激光多普勒流速仪测量精度的重要因素,因此精确获知测量体中干涉条纹间距及梯度分布情况,是激光多普勒流速仪准确测量流速的前提。对激光多普勒流速仪测量体中的干涉条纹间距及梯度分布进行了理论分析,揭示了高斯光束固有传播特性与其测量体中干涉条纹分布之间的关系,确定了影响干涉条纹分布的参数。使用光束分析仪分别获得绿光和紫光的束腰半径为114μm和83μm,并确定了束腰的空间位置,利用测得的相关参数量化了绿光和紫光测量体中任意位置的干涉条纹间距及梯度分布,绿光和紫光测量体中归一化后的条纹梯度最大分别可达0.46%和0.60%。通过与转盘装置所测得的绿光和紫光干涉条纹间距结果进行比较,对干涉条纹分布的理论分析及测量结果进行了验证,最大相对误差分别为0.87%和0.78%。
Laser Doppler flowmeter (LDV) has the advantages of high accuracy, non-contact measurement, fast dynamic response and is widely used in the measurement of flow rate. The inconsistency of fringes is an important factor that affects the measurement accuracy of laser Doppler velocimetry. Therefore, accurately knowing the interference fringe spacing and gradient distribution in the measurement body is the premise of accurate measurement of velocity by laser Doppler velocimetry. Theoretical analysis of the interference fringe spacing and gradient distribution in the laser Doppler velocimeter measurement body reveals the relationship between the inherent propagation characteristics of Gaussian beams and the distribution of interference fringes in the measurement body, and determines the parameters that affect the distribution of interference fringes. The beam waist of the green and violet light beams were obtained as 114μm and 83μm respectively by beam analyzer, and the spatial position of the beam waist was determined. The interference fringes of arbitrary positions in the green and violet light measuring bodies were quantified by using the measured parameters and The normalized fringe gradients in gradient, green and violet measurements were up to 0.46% and 0.60% respectively. The results of theoretical analysis and measurement of interference fringe distribution were compared with those of green and violet interference fringe measured by the turntable device. The maximum relative errors were 0.87% and 0.78% respectively.