液体混合过程分析测试系统

采用LaVision的sCMOS相机构成的PIV和PLIF测量系统，对双射流混合流进行了流体速度场和双色PLIF温度场测量研究。

采用LaVision的在液体中的激光诱导荧光测量系统FluidMaster进行了降膜在倾斜加热箔上的时间分辨浓度和温度分布测量，获得了时空分辨传热数据。

采用LaVision的结构化平面激光照明成像（SLIPI)技术，应用于多相流的激光诱导荧光测量系统中，有效地消除了背景反射的影响。可以准确有效地辨识多相流对象中的界面。

Two-phase annular flow is commonly used in both commercial and industrial heat transfer; however, we do not yet possess a thorough understanding of the nature of the fluid. Most analytical annular two-phase models are based on a relationship between the liquid film thickness, liquid film mass flux, and the axial pressure gradient or interfacial shear stress. The film thickness calculated from these models can then be utilized to determine the heat transfer coefficient of the flow. Although they are specific to certain flow regimes and fluids, empirical models remain more accurate than these analytical models. The key to understanding these flows lies with the liquid film. Therefore, to better understand the pressure drop and heat transfer of annular two-phase flow, this study involves the development of local, liquid velocity measurement techniques and their application to horizontal, wavy-annular two-phase flow. Two techniques, Bubble Streak Tracking (BST) and Thin Film Particle Image Velocimetry (TFPIV), have been developed in this study. Utilizing naturally occurring bubbles within the liquid film, the BST technique determines the liquid velocity by measuring reflected light streaks from the bubbles. A three-colored LED array creates directionally unambiguous streaks, while a strobe illuminates interfacial features that affect the liquid velocity. The TFPIV technique applies a typical micro-PIV system to a macroscopic flow with the addition of a non-trivial image processing algorithm. This algorithm successfully overcomes the image noise that occurs when applying PIV to a two-phase, thin film. Although difficulties arise when processing the BST data, the results of the BST and TFPIV methods are comparable, making BST an economical alternative to TFPIV for calculating liquid film velocities.

This dissertation presents a series of laboratory experiments to study flow and mixing properties of multiphase plumes. The particle image velocimetry (PIV) and laserinduced fluorescence (LIF) techniques are developed to measure two-dimensional velocity and concentration fields of multiphase plumes. The developed measurement techniques are applied to bubble plumes in different ambient conditions.