亚音速枪弹气动外形设计与阻力特性分析+数学模型
时间:2018-09-27 19:54 来源:毕业论文 作者:毕业论文 点击:次
| 摘要使用专业的网格生成器Gridgen，创建预先设计好的五种不同的7.62mm枪弹外形图和带刻痕的枪弹模型；然后创建曲线，定义面网格的边界，并对其进行分布网格点；生成面网格，再由面网格向周围扩展形成体网格；定义弹丸外部绕流条件和弹丸表面，输出.cas文件，导入fluent进行计算。28620 运用数值模拟方法计算了不同外形尺寸对某7.62mm枪弹阻力特性的影响规律。分别计算枪弹在不同圆柱部、尾部尺寸、尾部锥角及带刻痕时阻力系数随马赫数的变化，并与标准枪弹外形尺寸下的阻力系数变化规律进行比较。计算表明：枪弹圆柱部长度越小，阻力系数越小；尾锥部长达越大，阻力系数越小；在一定范围内，尾部偏转角越大，阻力系数越小；尾部截锥体的影响大于圆柱部长度的影响。带刻痕时枪弹阻力系数大于标准弹的阻力系数。 关键词 气动外形；阻力系数；气动特性；数值模拟；枪弹 毕业论文设计说明书外文摘要 Title The aerodynamic design and analysis of resistance characteristics about subsonic bullet Abstract Using professional grid generator Gridgen, create advance designed five different 7.62 mm bullet shape and bullets with Nick model; Then create a curve, define the boundary of the surface grid, and carries on the grid point distribution; Generate surface grid, the surface mesh expand to the surrounding a body grid; Define the projectile external flow condition and the surface of the projectile, output .cas file, import fluent to calculate. The method of numerical simulation was used to calculate the influence of bullet size on the drag coefficient of one 7.62mm bullet. Different cylindrical part, tail size or cone angle was calculated and the influence of nick was also considered in the simulation. From the comparison between the drag coefficient data changing with different much numbers in simulation and that calculated under standard bullet size. It is found that the larger the size of tail is taken, the smaller the drag coefficient is to be; the shorter the size of cylindrical part or bigger the tail angle is taken, the drag coefficient is smaller and the influence of the tail size is larger than the cylindrical part size. The coefficient of the bullet with nick is larger than the bullet with standard size. Keywords: aerodynamic shape; drag coefficient; aerodynamic characteristics; numerical simulation; bullet; 目 次 1 绪论 1 1.1 研究的目的及意义 1 1.2 国内外枪弹发展概况 1 1.3 枪弹气动力特性的研究方法 2 1.4 亚音速枪弹的发展趋势 3 1.5 本文研究内容 4 2 数学模型 5 2.1 控制方法和数值方法 5 2.2 计算模型、网格及边界条件 5 2.3 枪弹外形设计 6 3 枪弹外形对阻力系数影响的模拟结果及分析 8 3.1 标准弹在不同马赫数下阻力系数的模拟结果及分析 8 3.2 不同外形产生的阻力系数的模拟结果及分析 13 3.2.1 弹型②（减小尾锥度）与标准弹比较分析 13 3.2.2 弹型③（缩短圆柱部）与标准弹比较分析 16 3.2.3 弹型④（增长尾锥部）与标准弹比较分析 19 3.2.4 弹型⑤（缩短圆柱部，增长尾锥部）与标准弹比较分析 21 3.3 有无旋转对阻力系数的影响 24 4 刻痕对阻力系数的影响 28 4.1 同一转速下刻痕对阻力系数的影响 28 (责任编辑：qin) |