Three-dimensional transient numerical simulation of gas exchange process in a four-stroke motorcycle engine with a semi-spherical combustion chamber with two tilt valves was studied. Combination of the grid re-meshing...Three-dimensional transient numerical simulation of gas exchange process in a four-stroke motorcycle engine with a semi-spherical combustion chamber with two tilt valves was studied. Combination of the grid re-meshing method and the snapper technique made the valves move smoothly. The flow structure and pattern in a complete engine cycle were described in detail. Tumble ratios around the x-axis and y-axis were analyzed. Comparison of computed pressure with experimental pressure under motored condition revealed that the simulation had high calculation precision; CFD simulation can be regarded as an im-portant tool for resolving the complex aerodynamic behavior in motorcycle engines.展开更多
The problem of “strung balls”, which considers how many circles in a given family of circles can be intersected by a line in a plane, is discussed in R^n(n ≥ 3). Higher dimensional versions of the results given on ...The problem of “strung balls”, which considers how many circles in a given family of circles can be intersected by a line in a plane, is discussed in R^n(n ≥ 3). Higher dimensional versions of the results given on a plane are obtained.展开更多
文摘Three-dimensional transient numerical simulation of gas exchange process in a four-stroke motorcycle engine with a semi-spherical combustion chamber with two tilt valves was studied. Combination of the grid re-meshing method and the snapper technique made the valves move smoothly. The flow structure and pattern in a complete engine cycle were described in detail. Tumble ratios around the x-axis and y-axis were analyzed. Comparison of computed pressure with experimental pressure under motored condition revealed that the simulation had high calculation precision; CFD simulation can be regarded as an im-portant tool for resolving the complex aerodynamic behavior in motorcycle engines.
基金This research is supported by NSFC(China) Grant, TRAPOYT and China MOE Research Grant.
文摘The problem of “strung balls”, which considers how many circles in a given family of circles can be intersected by a line in a plane, is discussed in R^n(n ≥ 3). Higher dimensional versions of the results given on a plane are obtained.
