The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D ...The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D axisymmetric coordinate. The numerical method is based on least-square gridless method,and the inviscid flux is calculated by multi-component HLLC( Harten-Lax-van Leer-Contact) scheme,and a H2-CO reaction mechanism involving 9 species and 11 reactions is used. The computations are performed for the full projectile configuration of Ma = 1. 5,2,and 3. The hot air injection cases and inert cases are simulated for comparison. The numerical results show that due to the combustion in the weak region,the recirculation zone enlarges and moves downstream,the base pressure increases and the total drag force coefficient decreases. At Ma = 3. 0,the rear stagnation point shifts downstream approximate 0. 26 caliber,and the base pressure increases about 53. 4%,and the total drag force coefficient decreases to 0. 182 which agrees well with the trajectory model prediction. Due to neglecting the effects of viscosity and turbulence,there exists a certain difference at Ma = 1. 5,2. 0.展开更多
针对波达方向(Direction Of Arrival, DOA)估计在实际测向系统中系统复杂度受接收通道数目影响的问题,该文提出一种基于FRIDA(Finite Rate of Innovation Direction-of-Arrival)的多通道切换阵列DOA估计算法。该算法首先利用开关将特定...针对波达方向(Direction Of Arrival, DOA)估计在实际测向系统中系统复杂度受接收通道数目影响的问题,该文提出一种基于FRIDA(Finite Rate of Innovation Direction-of-Arrival)的多通道切换阵列DOA估计算法。该算法首先利用开关将特定子阵接收的数据传输至通道从而减少测向系统中使用的通道数目,然后通过切换不同的子阵接入通道并采样得到多个少通道接收数据协方差矩阵,利用这些协方差矩阵重构出全通道接收数据向量,以此来构建基于有限新息率(Finite Rate of Innovation, FRI)的DOA估计模型,最后通过近端梯度下降算法获得信号入射方向的估计结果。仿真实验与对实测数据的实验验证了该算法优于同等条件下的其它算法。展开更多
文摘The gridless method coupled with finite rate chemistry model is employed to simulate the external combustion flow fields of M864 base bleed projectile. The fluid dynamics process is described by Euler Equation in 2-D axisymmetric coordinate. The numerical method is based on least-square gridless method,and the inviscid flux is calculated by multi-component HLLC( Harten-Lax-van Leer-Contact) scheme,and a H2-CO reaction mechanism involving 9 species and 11 reactions is used. The computations are performed for the full projectile configuration of Ma = 1. 5,2,and 3. The hot air injection cases and inert cases are simulated for comparison. The numerical results show that due to the combustion in the weak region,the recirculation zone enlarges and moves downstream,the base pressure increases and the total drag force coefficient decreases. At Ma = 3. 0,the rear stagnation point shifts downstream approximate 0. 26 caliber,and the base pressure increases about 53. 4%,and the total drag force coefficient decreases to 0. 182 which agrees well with the trajectory model prediction. Due to neglecting the effects of viscosity and turbulence,there exists a certain difference at Ma = 1. 5,2. 0.
文摘针对波达方向(Direction Of Arrival, DOA)估计在实际测向系统中系统复杂度受接收通道数目影响的问题,该文提出一种基于FRIDA(Finite Rate of Innovation Direction-of-Arrival)的多通道切换阵列DOA估计算法。该算法首先利用开关将特定子阵接收的数据传输至通道从而减少测向系统中使用的通道数目,然后通过切换不同的子阵接入通道并采样得到多个少通道接收数据协方差矩阵,利用这些协方差矩阵重构出全通道接收数据向量,以此来构建基于有限新息率(Finite Rate of Innovation, FRI)的DOA估计模型,最后通过近端梯度下降算法获得信号入射方向的估计结果。仿真实验与对实测数据的实验验证了该算法优于同等条件下的其它算法。
