Study And Application Of Static And Dynamic Full-field Deformation Measurement Technique Of A Liquid Surface

Accurate measurement for static and dynamic deformation of a liquid surface plays asignificant role in the fields of biomechanics, fluid dynamics and aerospace industry, asexemplified by the huge influence of liquid propellants sloshing within fuel tanks on theattitude control, performance, and stability of liquid-filled spacecraft. As the ratio betweenpropellant and total mass increases, the impact of sloshing also increases. Hence, theaccurate measurement of nonlinear liquid sloshing dynamics has been of major concern toaerospace engineers studying. In this paper, it is committed to develop simple and effectivetechniques for full-field static and dynamic deformation measurement of a liquid surfacebased on the characteristics such as high transparency, low reflectivity and fluidity ofliquid.It is developed a technology which is able to measure the deformation of a liquidsurface by analyzing the distortion of transition light in this paper. Furthermore, four-stepphase-shifting fringe transmission technique (FP-FTT) are proposed, to accurately measurethe deformation of liquid surface with a thread made of lead-tin alloy floating on the watersurface, and the results are in good agreement with theoretical calculations. Additionally, animproved FTT which using only a single high-speed camera for multi-dimensional dataacquisition has been proposed for full-field dynamic measurement of a continuous liquidsurface, which has no static reference plane during its shape variation. The method canaccurately measure the dynamic deformation of a liquid surface for nonlinear liquidsloshing and Faraday waves, and it is also able to achieve the accurate measurement ofresidual liquid volume. Besides, the measurement sensitivity and the applicability ofvariable kinds of deformation carriers and processing methods have been discussed andanalyzed systematically. A multi-scale liquid surface deformation measurement techniquecombining the fringe and speckle patterns has been developed, and an experimentalverification was carried out, and the results obtained demonstrated the feasibility andreliability of this new method, which can provides a new approach for relevant researchersin the area of dynamic characteristics of liquid sloshing in the tank of space vehicles in thefuture.Compared with traditional measurement methods, in this paper, the sensitivity of newliquid surface deformation measurement methods is superior to one micro. The new measurement methods inherit most of the ordinary optical measurement technology such asa high sensitivity, full-field and noncontact measurements. Furthermore, they areoutstanding for its ease of operation and minimal effect on the measured object, as well asfeasible, reliable and low cost.