气动静/动稳定性的相关性及粘性滞后时间的研究

Study on Aerodynamic Static/Dynamic Stability Correlation and Viscous Lag Time

风洞试验证实 ,物体的气动静稳定性和气动动稳定性之间 ,存在着反向演变现象。研究表明 ,它主要是绕流的粘性效应诱导的气动量和它们对物体姿态运动的时间滞后引起的 ,并且 ,该气动量中的静稳定性粘性诱导量和动稳定性粘性诱导量之间是负相关的。本文给出了相关分析以及粘性诱导量之间的负相关模式 ,并用作者得到的风洞动态试验结果证明了上述负相关模式的实在性。此外 ,还根据上述风洞试验结果 ,计算了粘性动态相关因子Kd 与粘性滞后的时间tl 随Re的变化趋势 ,结果表明 ,Kd 比Re数要灵敏 ,并且 ,对尖锥也具有明确的规律性。

Wind tunnel tests have evidenced that there exists reversed evolution between aerodynamic static stability and dynamic stability of testing model, i.e.,within the range of static stability increase, dynamic stability decreases, or vice verse.Studies have shown that major reason for this aerodynamic phenomenon is viscosity induced aerodynamic forces and their time lag to model' s attitude movement.Besides, the static stability viscous induction component and the dynamic stability viscous induction component of this aerodynamic induction are in negative correlation . In this paper, correlation analysis and the reversed correlation mode between viscous induction components are given out as follows[C m ] i v=-K d[C mθ ] i v K d=t l/t c t c=d/u ∞  This correlation mode is in complete agreement with wind tunnel dynamic test results acquired by the author with 10° sharp cone respectively under natural transition and artificial transition. Besides, in this paper, based on this correlation mode,calculation is made out of dynamic viscosity correlation factor K d and viscous lag time t l versus Re as per mentioned wind tunnel test results, showing that they are Re' s negative exponential functions. Concludingly, in explaining the viscous effect of model' s dynamic aerodynamic cha racteristics, factor K d this dimensionless parameter might be more useful than Re. [WT5HZ]