高速风洞投放模型试验技术的关键问题及应用领域

基于高速风洞投放模型试验的经验，论述和总结了对试验技术的实际应用较为重要、且对试验结果有较大影响的几个关键问题：相似准则的选取问题、投放分离参数的模拟问题、风洞启动时流场对投放物模型的冲击载荷问题以及数据处理方法，分别对这四个问题的具体选取原则和处理方法进行了详细的总结和分析。重模型法能够确保模型投放轨迹的严格相似，但实用性较差；而轻模型法则正好相反。由于重模型法在实际使用中通常难以应用，因此轻模型法在风洞投放模型试验中获得了较多应用，但其模型垂直加速度不足的问题也需引起重视。投放分离参数的相似模拟，通常可通过采用弹簧或气缸提供的投放作用力来实现，弹簧具有简单、易行的特点，但模拟的准确性稍差；而气缸则正好相反。风洞启动时流场对投放物模型的冲击载荷问题常常能够影响到试验的顺利进行或影响试验结果。数据平滑处理可采用时间多项式拟合来实现，进而通过一次或二次微分获得气动力系数。对高速风洞模型投放试验的应用领域作了总结和介绍，将其分为飞机外挂物/内埋武器投放、子母弹抛撒/重块抛撒，以及头罩/导弹壳片分离三大类型试验，并对每一类试验在具体的试验技术，以及在上述几个关键问题上的特点分别作了介绍，给出了具体试验的图像和曲线。

Critical problems and applied fields of drop-model testing technique in high speed wind tunnel

Based onexperiences gained from drop-model tests in high speed wind tunnel, several critical problems are summarized for the test technique.Those problems are significantly important,and have great effect on the test results.The problems are,respectively,the choice of scaling laws,accurate simulation of separation parameters,instantaneous impact force exerted on the store model at the time of wind tunnel starting,and data extraction.The principle to choose solving methods and operation procedures are provided for the four problems.A careful investigation is needed for the four critical problems before the wind tunnel test,which is helpful to insure high accuracy of the test results.Heavy Scaling can secure the correct path for the model,but it is hard to be applied.The Light Scaling is opposite to the Heavy Scaling,and is used much more commonly in wind tunnel drop-model test.However,corrections are needed for deficiency of vertical acceleration in the Light Scaling.The model ejector force is accomplished by using springs or air cylinders.The spring is easy to be operated,while its accuracy of simulation is lower than that of the air cylinder.When the wind tunnel starts up,the impingement of air current on the model always affects the operation or the result of the test.The experimental data are smoothed by a function of time,and then differentiated to acquire aerodynamic coefficients. The applied fields are introduced for drop-model testing technique in high speed wind tunnel. These fields can be classified as jettisons of airborne external stores or internal missile separation, submunition disperse or weights disperse,and shroud separation or cover separation.The specific test technique and its characteristic are analysed with respect to the four critical problems, including the choice of scaling laws,the effect of gravitational acceleration deficiency on the test results for the Light Mach Scaling,and the choice of simulation methods of separation parameters.The specific test images and curves,regarding displacement,velocity and acceleration,are present for different high speed wind tunnel drop-model tests.