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.
北京欧兰科技发展有限公司为您提供《液体流体中流速检测方案(粒子图像测速)》,该方案主要用于其他中流速检测,参考标准《暂无》,《液体流体中流速检测方案(粒子图像测速)》用到的仪器有德国LaVision PIV/PLIF粒子成像测速场仪、Imager sCMOS PIV相机、液体混合过程分析测试系统。