【作者】 陈鹏；

【导师】 张敏；

【作者基本信息】 南京理工大学 ， 热能工程， 2014， 硕士

【摘要】 本文将工程算法与数值计算相耦合,求解高速弹头在不同飞行条件下的气动热环境,为弹头气动热环境的改善以及具体数值的预测提供一定的参考价值。首先,将弹头简化模型分为三部分：驻点处、半球部分以及锥身处。驻点处采用简化后的修正Lees公式,半球处根据球面几何关系结合Lees钝体热流密度公式变换推导得到热流密度计算式,而锥身处则由平板绕流的相似性解出发,推导得到相同雷诺数条件下的圆锥绕流层流与湍流状态的斯坦顿数St,最后代入弹头锥身得到热流密度公式。同时,在商业软件Tecplot8.0中建立弹头模型并绘制非结构化网格,并使用Fortran语言编写二维稳态导热程序,读取非结构化网格而后进行数值计算。有关热流密度的计算公式以第三类边界条件的方式赋给弹体表面,弹体内部的网格控制体基于有限容积法进行数值运算。本文研究内容分为三部分：边界层转捩、前缘钝度对高速弹头气动热环境的改变以及高温效应在气动热具体数值预测中的影响。转捩的计算采用Batt准则,在4-9Ma的来流条件下,分别对层流与湍流两种状态进行了数值计算；而考虑到前缘钝度对气动热环境的改变,文中建立了两种不同钝度的弹头模型分别计算,并将结果线性化处理和分析；最后部分考虑将空气视作量热完全气体和热完全气体两种条件,分析高温效应对高速弹头气动热具体数值预测的影响,这里利用热完全气体热力学参数与温度的拟合关系式,得到相应温度下的比热比γ并编写进导热程序中。计算结果表明,湍流状态下,弹头高温区域较于层流有所扩大,且转捩起始点随着马赫数的增大而前移,气动热环境逐渐严峻；前缘钝度的提高可以有效降低驻点及表面的热流,高温区域的温度值也有所降低,但弹头整体的气动阻力增大；在热完全空气的条件下,比热比γγ随激波后气流温度升高而降低,空气分子的振动能被激发,数值计算得到的弹头表面温度较于量热完全气体条件要低。上述结论在导弹研发初期以及气动热具体数值的预测中具有一定的参考价值。更多还原

【Abstract】 The aerodynamic heating and temperature fields over projectiles’ head at high speed in different flight conditions were calculated by using the coupling between the engineering method and numerical computation.Firstly, the reduced model of the projectiles’ head was divided into three partitions:stagnation point,hemisphere and cone body. The heat flux of stagnation point was calculated by simplified and modified Lees formula. Then on the hemisphere it was deduced by the coupling of the spherical geometry relationship and Lees heat flow formula on blunt body. But the caculation of the cone body began from the similar solution of flat-plate flow. The solution was deduced to get Stanton number of the same Reynolds number. The St number would be substituted into calculation for the heat flux of cone body.At the same time, the unstructured grid of the model was ploted in Tecplot8.0and the program of2-dimensional stead-state heat conduction would be writed inside Fortran language. Meanwhile, all the formulas would be assigned to the head surface as the third boundary condition.There were three parts in this research of the paper:the influences of the boundary layer transitions and blunted wedge of the cowl for the aerodynamic heat, the high-temperature effects on prediction for the specific numerical. The transition that based on Batt criteria was calculated under4-9Ma. Meanwhile, the paper modellings two different dullness heads for the research about alter of the aerodynamic heat. At last, the air could be regarded calorically perfects gas and thermally perfect gas. The high-temperature effects on prediction for the specific numeric would be analysed. This specific heat ratio was obtained from fitting formula between thermodynamic parameter and temperature.The calculations indicate that:compared to laminar flow, the high-temperature area on the head would expand under turbulence; The transition starting point woud antedisplace as the Mach number increases; Increasing the head dullness could effectively reduce the flux of the head. The average temperature on the head would be lower than the uniform conditions with calorically perfects gas. The above conclusion would take some reference value on the prime design of missles and prediction on the specific value of areodynamic heat.更多还原