Image Measurement Of Two-Phase Flow Characteristic In Centrifugal Pump Impeller

In recent decade years, with the development of the image measurement technology, application domain of it is becoming broader and broader. Now the image measurement technology is accepted and regarded as a fundamental measurement method for flow fields.This dissertation investigates image measurements of two-phase flow fields inside the pump impeller sponsored by the Opening Fund of Water Conservancy Dynamical Engineering Lab of Yangchou University, Jiangsu province, and consists of three main parts. Firstly, a minitype centrifugal pump was designed and used to set up an experimental model desk of two-phase centrifugal pump. Secondly, image measurement technology was taken to study particle-liquid two-phase flow in the centrifugal pump impeller. Thirdly, image measurement technology was also taken to study gas-liquid two-phase flow in the centrifugal pump impeller.In the first part, the method of velocity coefficient was used to design a 100mm diameter impeller with five single-arc-cylinder blades, and the method of velocity moment was applied to design the volute' s cross-section. The volute' s cross-section is a rectangle, which was designed as a whole structurewith the front shroud of the pump. A special lighting window was designed on the side. A water cycle system was set up to test the performance of the designed pump. The experimental model desk that was based on the cycle system was established.In the second part, a few kinds of particles with different densities and sizes were picked and used to study the trajectories and the distributions inside the pump impeller. From the experimental results, conclusions of particles' trajectories can be drawn for different densities and operating conditions. Three axis segments were acquired, and three operating conditions were picked to study the distribution traits of particles inside the impeller under the different quality and concentration of the particles. Based on the results, local wear of pump was forecasted and protecting measures were brought forward.In the third part, the performance was test when the pump worked under the best operating condition. From the result, three gas concentrations were selected to study the settle of bubbles inside the impeller under three kinds of operating conditions with three axis measurement segments. And trajectories of bubbles were also studied under the different operating conditions. All of the problems were theoretically analyzed when the pump transport the gas-liquid two-phase flow. Some improving measures were also put forward.Most of the dissertation is initial endeavors into a field heretofore very little explored, and contribute substantially to the understanding of the complex two-phase flow features in centrifugal pump impeller.