不同飞行状态下固体火箭发动机尾喷焰数值研究

为了研究飞行状态对固体火箭发动机尾喷焰的影响,建立了含化学反应项和组分输运项的N-S(Navier-Stokes)控制方程,并采用MUSCL(monotonic upstream-centered scheme for conversation laws) Roe格式的有限体积法进行求解.在此基础上,结合热力计算结果对某固体火箭发动机在不同飞行状态下的化学反应流和单一组分流进行仿真计算.结果表明:初始倾角和第一马赫波节长度随飞行高度的增加而增大,随来流马赫数的升高而减小.同单一组分流相比,化学反应流对第一马赫波节的影响较初始倾角显著.射流轴线温度因飞行状态的不同有较大涨落差异.初始倾角、第一马赫波节由来流总压决定,射流轴线温度由激波结构、复燃效应、来流条件等因素共同决定.      

Characterization of Solar Coronal Holes and Plumes Using Spectroscopic Diagnostic Techniques Applied to SOHO/CDS Observations

Results from a series of SOHO/Coronal Diagnostic Spectrometer (CDS) observations of coronal holes and plumes are presented, including analysis of a low-latitude plume observed in August 1996. Spectroscopic diagnostic techniques using the CHIANTI atomic database are applied to derive the plasma parameters: electron density, temperature, and element abundances. The results are compared with quiet sun values. Coronal electron densities in the holes are found to be about 2 × 10⁸ cm^-3, a factor of two to three lower than in the quiet sun. The plasma thermal distribution exhibits differences between coronal holes, the quiet sun and plumes. For example, the peak of the emission in coronal holes is at a lower temperature (T ⋍ 8 × 10⁵ K) than in the quiet sun (T ⋍ 1 × 10⁶ K), while plumes are cooler (T ⋍ 7.6 × 10⁵ K) and show a different distribution, closer to an isothermal state. This revised version was published online in June 2006 with corrections to the Cover Date.