弹用内乘波式进气道起动性能研究

 为弄清内乘波式进气道在低马赫数状态下的流动特征,分析影响内乘波式进气道起动能力的因素,研究与弹体匹配设计的内乘波式进气道的起动问题。首先基于一种有利于出口均匀性的基本流场,采用流线追踪技术,设计了来流马赫数为4.0且进出口形状适应弹体安装要求的双模块弹用内乘波式进气道;此后,采用计算流体力学(CFD)方法获得了低马赫数下进气道的三维波系结构和流动特征。研究表明,进气道溢流口位置是影响内乘波进气道起动能力的重要因素:在溢流口位置由两侧改至最下端后,起动马赫数由3.6下降为3.3;采用单模块方案,溢流口设置在下端后,起动马赫数下降为3.25。此外,设计内乘波式进气道基本流场也对起动性能有影响:设计出口马赫数不变,双模块方案下,入口气流偏转角每增大2°,起动马赫数约下降0.1;单模块方案下,提高入口气流偏转角最大可使起动马赫数下降为3.1;进气道内收缩比对起动能力的影响体现在入口气流偏转角不变时,进气道起动能力仅取决于内收缩比,设计出口马赫数每增加0.2,起动马赫数约减小0.2。研究所分析的各个弹用内乘波式进气道在设计条件下均可捕获99%的来流,在扩大了工作马赫数范围的同时,保持了高流量捕获性能和高总压恢复系数的优势。

Research on Start Ability of Modular Internal Waverider Inlet

Two modular internal waverider inlets are designed at freestream Mach number of 4.0,whose intake and exit are fit for the forebody of the missile,in order to find out the flow characteristics at lower design points and analyze the factors which have an impact on the start ability of the internal waverider inlet.They are based on a basic flow field which has an uniform outflow and has been derived with the technology of stream tracing.Computational fluid dynamics(CFD) results show that the inlets have unique shock structures and flow characteristics at lower Mach number.Flooding position is one of the most important factors which can affect the start ability of the internal waverider inlet.The start Mach number reduces from 3.6 to 3.3 when the flooding position is changed from sides to bottom,further to 3.25 with one modular inlet.Besides,the basic flow field plays an important role in reducing the start Mach number.With the design exit Mach number fixed,the start Mach number nearly decreases by 0.1 when the turn angle increases by 2° with two modular inlets and can reduce to 3.1 with one modular inlet.With the intake turn angle fixed,the start ability of the inlet is only decided by the internal contraction ratio.The start Mach number almost reduces by 0.2 when the design exit Mach number increases by 0.2.The modular internal waverider inlet can capture nearly 99% incoming flow at different design points and shows the advantages of high flow capture ability and high total pressure recovery coefficient while the working range is enlarged.