Liquid Phase Velocity Profile Measurement in Two-Phase Flow by Micro Tracer Method

气液两相流的液相速度分布是了解两相流流动机理的重要信息。应用微示踪法测量了两相流中液体的速度分布，并讨论了这些方法的有效性。将气泡时间线法应用于空气-水两相水平流动。该方法适用于气液速度均较低的分离流。当气速高时，液速也会变高，无法清晰地分辨出氢气气泡。然而，如果粒子图像测速技术应用于氢泡轨迹，则被认为概率很高。在圆管内垂直向上的两相犁中，利用CCD相机对液相中含有的细颗粒进行跟踪。该方法是一种粒子图像测速技术。为了精确地确定圆管内的测量位置，设计了光学系统并推导了几何关系。所得结果对单相水流是令人满意的。对于气液两相流，无法获得准确的数据。这是由于在靠近壁的测量点处示踪剂的数量很少，而且现有光学系统的精度产生了相当大的误差。

Liquid phase velocity profile of gas-liquid two-phase flow is an important information to understand the flow mechanism of two-phase flow. Micro tracer mathods were applied to measure the liquid velocity profile in two-phase flows and validity of these methodes were discussed.The time line method by using hydrogen bubbles was applied to a air-water two-phase horizontal flow. This method is valid for the separated flow when both the gas and liquid velocities are relative low. When the gas velocity is high, the liquid velocity becomes high and hydrogen bubbles cannot be clearly distinguished. However, Probability is considerd to be high if the particle image velocimetry technique is applied to hydrogen bubble traces.For the vertical upward two-phase plow in a round tube, fine particles were contained in the liquid phase and traced by making use of CCD camera. This method is a particle image velocimetry techique. To determine precisely the measurement position in a round tube, an optical system was designed and geomerical relations were drived. Results obtained for the single phase water flow are satisfacrory. For the gas-liquid two-phase flow, accurate data cannot be obtained. This is attributable to the fact that the number of tracer is very small at measurement points close to the wall and that the accuracy of the present optical system generates considerable error.