气动量仪锥度管内流场对浮标稳定性分析

从绕流问题入手，通过流场分析研究发现气流自下而上经过浮标后会引发尾部紊流和涡旋。随着涡旋移动脱落，湍动流场就会呈现脉动压力以交变形式作用于浮标两侧，引发浮标左右摇摆，示数不稳。进一步在浮标尾部设计增加不同长度和角度的导向面，通过对尾部流场引流来降低尾部旋涡的影响；同时增强引流导向区局部气阻提高浮标的工作稳定性。研究发现:当导向面长度增大至2 mm时，浮标与锥度管道内壁气流刚度增强，浮标偏转角由$\mathrm{8}°$降低至$\mathrm{0.5}°$。当导向面角度超过$\mathrm{10}°$时，受科恩达效应的影响,浮标出现相对低压区，偏转角超过$\mathrm{15}°$。 

Stability analysis on flow field within taper tube of pneumatic measuring instrument in relation to buoy

The problem of flow around the buoy was analyzed.It was found that the tail turbulence and vortices were caused when the flow passed through the buoy from bottom to top.As the vortex moved and fell off，the turbulent flow field showed fluctuating pressure acting on both sides of the buoy in an alternating form，causing the buoy to swing from side to side and the indicator to be unstable.Further，a guide surface with length and angle was added at the tail of the buoy to reduce the influence of tail-vortex by draining the flow field at the tail.At the same time，the local air resistance in the drainage guide area was enhanced to improve the working stability of the buoy.The results showed that when the length of the guide surface increased to 2 mm，the airflow stiffness of the buoy and the inner wall of the glass pipe increased，and the deflection angle of the buoy decreased from $\mathrm{8}°$ to $\mathrm{0.5}°$.When the angle of the guide surface exceeded $\mathrm{10}°$，a relatively low pressure area appeared and the deflection angle exceeded $\mathrm{15}°$ due to the influence of the Cornda effect.