超音速气流中受热壁板的稳定性分析

STABILITY ANALYSIS OF HEATED PANELS IN SUPERSONIC AIR FLOW

夏巍 杨智春

采用Galerkin方法建立二维壁板的非线性气动弹性运动方程,用一阶活塞理论模拟壁板受到的气动力.基于李雅普诺夫间接法分析了平壁板的稳定性,得到了壁板失稳的边界曲线;采用牛顿迭代法分析了壁板的屈曲变形,进而分析了后屈曲状态下壁板的稳定性;在时域中分析了后屈曲状态下壁板的颤振边界.分析结果表明,为了保证计算精度,在二维壁板的静态失稳及过屈曲变形分析中,至少要取二阶谐波模态;在平壁板的超音速颤振（动态失稳）边界分析中至少应取四阶模态.还对壁板的温升,壁板长厚比、壁板密度和气流马赫数作了无量纲变参分析,研究了这些参数的变化对壁板稳定性的影响规律.研究中发现,当气流速压较低时壁板一般会稳定在低阶谐波模态的屈曲变形位置,但是如果系统出现多个渐近稳定的不动点,即使作用在壁板上的气流速压很低,壁板也有可能在较低速压下发生二次失稳型颤振.[著者文摘]

　An investigation on stability of heated panels in supersonic air flow is carried out in this paper. A nonlinear aeroelastic model for a two-dimensional heated panel is established using Galerkin method.The quasi-steady piston theory is employed to calculate the aerodynamic load on the panel and the even temperature field is considered.At first,the static and dynamic stabilities for flat panels are studied by using Lyapunov＇s indirect method and the stability boundary curve is obtained.Then the static deformation of a post-buckled panel is calculated by Newton iterative approach,and the local stability of the post-buckling equilibrium is analyzed.The results show that a two-mode model is suitable for panel static stability analysis and static deformation calculation;but more than four modes are required for dynamic stability analysis.The effects of temperature elevation and non-dimensional parameters related to panel length/thickness ratio,material density and Mach number on the stability of heated panels are also investigated.It is found that panel flutter（secondary instability）may occur at relatively low aerodynamic pressure when there are several stable equilibrium points for the aeroelastic system of heated panels.[著者文摘]

用微分求积方法计算二维薄板在超音速流中的非线性颤振

THE NONLINEAR PANEL-FLUTTER OF A TWO-DIMENSION THIN PLATE IN THE SUPERSONIC FLOW BY DIFFERENTIAL QUADRATURE METHOD

陈大林[1,2] 杨翊仁[1] 范晨光[1]

采用了一种微分求积方法将二维薄板在超音速气流作用下的非线性动力学方程离散为常微分方程，并用Runge-Kutta数值方法进行了计算。为验证微分求积方法的结果，与伽辽金方法计算结果进行了比较，取得了一致的结果．微分求积法的计算结果用分叉图、相平面、时域曲线以及功率谱进行了描述，结果表明在特定的参数区间存在混沌运动，而通向混沌的道路是经过一系列周期倍化分叉产生的。[著者文摘]

A new method called differential quadrature method （DQM） is introduced to formulate the discrete forms of the dynamic equation of a two-dimension thin plate subjected to supersonic airflow. Numerical analysis is couducted by Runge-Kutta numeric method. To verify the DQM, a comparison between the results obtained from DQM and those obtained by the Galerkin approach is made and it is found that both agree very well. The results are showed sketchily, such as bifurcation diagram, phase-plane plots, time history diagrams and power spectrum plots. The results indicate that chaotic motions exist in certain ranges of the parameter space of the system, and the route to chaos is via doubling-period bifurcation.[著者文摘]

多层微穿孔板的优化设计

Multilayer Micro Perforated Panel Optimization Design

张晓杰 赵晓丹

影响微穿孔板吸声系数的结构参数很多，设计计算复杂，尤其是对多层微穿孔板复合结构的计算。针对3层及4层微穿孔板复合结构的吸声系数进行了计算，应用遗传算法对其结构参数进行了优化，在常用噪声频率范围内获得了非常饱满的吸声系数曲线，与双层微穿孔板复合结构相比，在吸声系数和吸声频带上都有了很显著的提高。[著者文摘]

There are some parameters that influence the performances of the micro perforated panel, which is difficult to be designed especially for the muhilayer micro perforated panel. The absorption coefficients of three and four layer micro perforated panel are calculated. Then the parameters of structure are optimized by the genetic algorithm, which can get exactly satisfactory absorption curve during the usual noise frequency area. Contrasted with the double micro perforated panel, the absorption coefficient and frequency range are improved remarkably.[著者文摘]

新型OSB拌胶机工作参数对OSB力学性能的影响

Effects of new OSB blender operating parameters on mechanical performance of OSB

谢敏芳 谢拥群 林铭 魏起华

研究新型定向刨花板拌胶机的不同工作参数对拌胶刨花压制成的OSB板子性能的影响，试验结果表明：拌胶机滚筒的装载量以刨花占滚筒容积15％为宜，最佳转速为13r·min^-1，采用抄板气流流态控制和针滚机械干涉方法，均能使刨花处于良好的受胶状态，胶液均匀分布，提高板子的力学性能。[著者文摘]

Research on the effects of different operating parameters of the new OSB blender on the performance of OSB made by blended particle （or strand） was conducted. The results showed that the state of particle is suitable for absorbing glue, that the glue distribution on the particle surface is even and the mechanical properties of OSB is improved on condition that the particle loadage of blender drum particle is 15% of the blender drum volume, the drum speed is 13 r.min^-l , the air state of air-flow-control panel is adjusted and needle roller device control is adopted.[著者文摘]