Research On Bubble Dynamics In Flow Field And Parameter Detecting Of Two-phase Flow

In this paper,the issues related to two-phase flow were studied based on the background of spacecraft on-orbit refueling.As the speed of transferring propellant maybe too fast,the propellant transferred will be involved with bubbles.The existence of bubbles in propellant will lead flowmeter failure.Based on this background,The main work of this thesis is as follows.First,derived from the mass equation,the momentum equation and bubble model,analyses the pressure equilibrium around the bubble wall,the oscillation equation of bubble wall is developed.Through numerical solutions,the influence of the oscillation of bubble wall is studied.Furthermore,a linear model of bubble dynamics is studied;the bubble oscillation damping and resonance frequency are investigated.The result shows that environmental pressure and bubble radius have effect on oscillation damping and resonance frequency.Then,the model of homogeneous medium is introduced when the issues of two-phase flow are investigated.Propagation equation of acoustic wave in two-phase flow is derived based on the mass equation and the momentum equation.Simultaneous equation of oscillation equation of bubble wall and propagation equation of acoustic wave in two-phase flow is studied.The facts that influence the propagation of acoustic wave in two-phase flow is analysed.Based on the analysis before,two kinds of ultrasonic methods to detect the void fraction are investigated.One is void fraction detection based on single frequency acoustic attenuation and another is based on double frequencies.The numerical result shows that the methods introduced upon are feasible.At last,experiment is designed to achieve to detect void fraction based on the method of single frequency acoustic attenuation.The paper investigates the bubble dynamics and parameter detecting of two-phase flow on theoretical,numerical and experimental validation.The work in the paper enriches the bubble dynamics theory,provides valuable reference to detectie parameter of two-phase flow which enjoys great significance both for theoretical study and engineering practice.