周向平均形式的S_2流面计算

本文按照周向平均的方法,应用古川、井上给出的周向平均形式的平衡条件式,对翼形斜流叶轮考虑非轴对称时的S_2流面进行了计算,并将它与轴对称时的计算结果作了比较。     

Thermal expansion effect on the propagation of premixed flames in narrow channels of circular cross-section: Multiplicity of solutions,axisymmetry and non-axisymmetry

The present study examines, in presence of thermal expansion effects, the existence of the multiplicity of solutions previously reported within the context of diffusive-thermal modeling in [15], for lean premixed flames with low Lewis number (Le?<?1) propagating in narrow circular adiabatic channels subject to a Poiseuille flow. For this, direct numerical simulations have been carried out within the framework of variable-density Navier–Stokes equations and zero-Mach-number approximation. The simulations, conducted for both axisymmetric and three-dimensional cylindrical geometries, confirm the coexistence of multiple steady flame structures for a given flow rate. They show that axisymmetric flames concave towards the upstream are more unstable to three-dimensional perturbations than convex (toward the upstream) flames. This result evinces earlier findings obtained from stability analysis. The non-axisymmetry property of the flame is also found to push back the critical flashback limits at larger flow rate when compared to those predicted under the assumption of flame axisymmetry.