微射流作动器外流场数值模拟

Detailed Numerical Simulation of External Flow Field of Micro-Jet Actuator

采用隐式高阶紧致差分格式结合 Beam- Warming近似因式分解法求解全 N- S方程 ,对二维、粘性、非定常、可压微作动器外流场进行数值模拟。内置似牛顿子迭代用来消除因近似因式分解、线性化、显式边界条件及隐式一边采用低阶空间离散所带来的误差 ,以提高精度。隐式高阶紧致差分格式具有高的精度和强的稳定性。与其它人工粘性方法相比 ,隐式高阶数值过滤方法 ,尤其对马赫数很低的流场计算有明显优越性。计算结果揭示了微射流的特点及其产生、发展与耗散的过程。

Although the method of Rizzetta et al [4] can be applied to perform numerical simulation of external flow field of micro jet actuator, it leaves out many essential details. We aim to include these essential details for numerical simulation of a micro jet actuator external flow field that is compressible, two dimensional, time dependent, and viscous. Essentially section 1 includes details about: (1) solution of the full Navier Stokes equations using Beam Warming approximate factorization method and a high order compact difference scheme; (2) use of Newton like sub iterations within each physical time step to achieve time domain accuracy, to remove factorization errors, and to reduce errors caused by linearization and by the low spatial order of accuracy of the implicit operator. Section 1 also mentions three observations: (1) that implicit high order compact difference scheme is robust for our problem; (2) that our proposed algorithm is highly accurate compared with both second order and upwind biased methods; (3) that, for certain cases, particularly very low Mach number flows, filtering is a superior alternative to damping. Section 2 gives a specific example of numerical simulation external flow field of micro jet actuator. Figs.1 and 2 give numerical simulation results. Figs.3 and 4 are results taken form Refs.3 and 1 respectively. Comparison of our numerical simulation results with those in Refs.3 and 1 shows preliminarily that the details we give for numerical simulation external flow field of micro jet actuator are satisfactory.