Numerical Investigation Of Vortex Shedding From Rectangle Cylinders Scoured By Gas-liquid Two-Phase Flow

There is widely gas-liquid two-phase cross flow in industrial fields, such as power, chemical industry, nuclear power, refrigeration, petroleum, metallurgy, and etc. Under certain conditions, the flow behind cylinder forms the alternate vortex street and the vortex street causes the alternate pulsating force on the cylinder, therefore the fatigue damage reduces the industrial equipment service life greatly. When the vortex street frequency is consistent with the cylinder natural frequency, resonating create the enormous destruction. In order to promote the gas-liquid two phase vortex streets and the cylinder interaction mechanism research development and provide the full scientific basis to the industrial equipment design as well as the safety analysis, combing the Natural Sciences Foundation project of China (50676017), the key science and technology research project (206037) of Ministry of Education, this article carries on the numerical simulation of gas-liquid two phase flow around the square cylinder, the two side-by-side square cylinders, the rectangular cylinder.The governing equations of gas-liquid two phase flow are obtained based on the volume-average method. The two-fluid model & RNG k ?εturbulence model was used in the gas-liquid two phase flow with the enhanced wall function for the near wall treatment. With the help of numerical calculation, we find that the incident flow Reynolds does not influence the flow field characteristic when blunt body has sharp border. The void fraction enlargement contributes to suppressing stable vortex street forming; the air void distribute according to the whirlpool type, mainly concentrating both sides of the cylinder which has low pressure. For gas-liquid two phase flow around two side-by-side square cylinders, It is found that the gap flow with the spacing ratio smaller than 2.0 is not only biased to one side, resulting in the formation of a narrower wake behind one cylinder and a wider wake behind the other, but also not-biased to neither of them; vortex shedding from the two cylinders with the spacing ratio larger than or equal to 2.0 is synchronized. But when the spacing ratio is equal to 2.0, In-phase mode is the predominant mode while anti-phase mode predominates when the spacing ratio larger than 2.0. In bias pattern, the cylinder with wide wake has smaller resistance, the cylinder with narrow wake has larger resistance, and the cylinders with middle wake have equality resistance. Meanwhile the spacing ratio has tremendous influence on pulsating lift, amplitude spectrum and so on.This paper is composed of six parts. There are respective chapter one introduction, chapter two gas-liquid two phase cross flow computation model, chapter three vortex shedding characteristics of gas-liquid two phase flow around a single square cylinder, chapter four vortex shedding characteristics of gas-liquid two phase flow around two side-by-side square cylinders, chapter five vortex shedding characteristics of gas-liquid two phase flow around a single rectangle cylinder and the summary and the forecast.