A novel high-order three-dimensional(3-D)discontinuous Galerkin time domain(DGTD)method based on a normalized formulation of Maxwell′s equations is developed for modeling and simulating silicon-on-insulator(SOI)thin-...A novel high-order three-dimensional(3-D)discontinuous Galerkin time domain(DGTD)method based on a normalized formulation of Maxwell′s equations is developed for modeling and simulating silicon-on-insulator(SOI)thin-ridge waveguide.The DGTD method employs unstructured meshes and piecewise high-order polynomials for spatial discretization,and Runge-Kutta methods for time integration.It is found that the numerical results of the leakage loss of SOI thin-ridge waveguide agree well with those of analytical solutions,which proves that the proposed method is an ideal tool for the quantitative analysis for SOI thin-ridge waveguide.展开更多
In order to reduce the losses caused by tip-leakage flow, axisymmetric contouring is applied to the casing of a two-stage unshrouded high pressure turbine（HPT） of aero-engine in this paper. This investigation focuse...In order to reduce the losses caused by tip-leakage flow, axisymmetric contouring is applied to the casing of a two-stage unshrouded high pressure turbine（HPT） of aero-engine in this paper. This investigation focuses on the effects of contoured axisymmetric-casing on the blade tipleakage flow. While the size of tip clearance remains the same as the original design, the rotor casing and the blade tip are obtained with the same contoured arc shape. Numerical calculation results show that a promotion of 0.14% to the overall efficiency is achieved. Detailed analysis indicates that it reduces the entropy generation rate caused by the complex vortex structure in the rotor tip region, especially in the tip-leakage vortex. The low velocity region in the leading edge（LE） part of the tip gap is enlarged and the pressure side/tip junction separation bubble extends much further away from the leading edge in the clearance. So the blocking effect of pressure side/tip junction separation bubble on clearance flow prevents more flow on the tip pressure side from leaking to the suction side, which results in weaker leakage vortex and less associated losses.展开更多
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘A novel high-order three-dimensional(3-D)discontinuous Galerkin time domain(DGTD)method based on a normalized formulation of Maxwell′s equations is developed for modeling and simulating silicon-on-insulator(SOI)thin-ridge waveguide.The DGTD method employs unstructured meshes and piecewise high-order polynomials for spatial discretization,and Runge-Kutta methods for time integration.It is found that the numerical results of the leakage loss of SOI thin-ridge waveguide agree well with those of analytical solutions,which proves that the proposed method is an ideal tool for the quantitative analysis for SOI thin-ridge waveguide.
文摘In order to reduce the losses caused by tip-leakage flow, axisymmetric contouring is applied to the casing of a two-stage unshrouded high pressure turbine（HPT） of aero-engine in this paper. This investigation focuses on the effects of contoured axisymmetric-casing on the blade tipleakage flow. While the size of tip clearance remains the same as the original design, the rotor casing and the blade tip are obtained with the same contoured arc shape. Numerical calculation results show that a promotion of 0.14% to the overall efficiency is achieved. Detailed analysis indicates that it reduces the entropy generation rate caused by the complex vortex structure in the rotor tip region, especially in the tip-leakage vortex. The low velocity region in the leading edge（LE） part of the tip gap is enlarged and the pressure side/tip junction separation bubble extends much further away from the leading edge in the clearance. So the blocking effect of pressure side/tip junction separation bubble on clearance flow prevents more flow on the tip pressure side from leaking to the suction side, which results in weaker leakage vortex and less associated losses.
