In the course of studying on aerodynamic change and its effect on steering stability and controllability of an automobile in passing, because of multi interaction streams, it is difficult to use traditional methods, s...In the course of studying on aerodynamic change and its effect on steering stability and controllability of an automobile in passing, because of multi interaction streams, it is difficult to use traditional methods, such as wind tunnel test and road test. If the passing process of an automobile is divided into many time segments, so as to avoid the use of moving mesh which takes large calculation resource and CPU processing time in calculating, the segments are simulated with computational fluid dynamics （CFD） method, then the approximate computational results about external flow field will be obtained. On the basis of the idea, the change of external flow field of wagon-shaped car at the moment of passing is simulated through solving three-dimensional, steady and uncompressible N-S equations with finite volume method. Numerical simulation analysis of side force coefficient, stream lines, body surface pressure distribution of wagon-shaped car are presented and a preliminary discussion of aerodynamic characteristics of correlative situations is obtained. Finally, the C3 -x/l curve of side force coefficient（C3） of car following relative distance （x/l） between cars is obtained. By comparison, the curve is coincident well with the experimental data, which shows creditability of numerical simulation methods presented.展开更多
A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord ...A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord could be passed through a straight pipeline 150 meters long and a roll of vinyl tube 50 meters long. However, under the same condition, the cord could not pass through when using the turbulent flow. To obtain a high speed stable spiral flow, a nozzle with an annular slit connected to a conical cylinder was used. A pressurized fluid with no tangential flow was supplied through this slit and the fluid, passing through the conical cylinder, was deformed into spiral flow with the steeper axial velocity distribution compared to that of turbulence pipe flow due to Coanda effect and instability. As a result, the cord was attracted to the axis area of the pipe, which effectively increased the ability for the work of cord passing. This high ability for cord passing is attributed mainly to the reduction of the friction made between the cord and the pipe wall, caused by the deformation to spiral flow.展开更多
PROOS is a distributed operating system running on the computing nodes of massively parallel processing computer Dawning-1000. It is an efficient and easily extendible micro kernel operating system. It supports the in...PROOS is a distributed operating system running on the computing nodes of massively parallel processing computer Dawning-1000. It is an efficient and easily extendible micro kernel operating system. It supports the intel NX message passing interface for communication.展开更多
基金National Natural Science Foundation of China(No. 50275052).
文摘In the course of studying on aerodynamic change and its effect on steering stability and controllability of an automobile in passing, because of multi interaction streams, it is difficult to use traditional methods, such as wind tunnel test and road test. If the passing process of an automobile is divided into many time segments, so as to avoid the use of moving mesh which takes large calculation resource and CPU processing time in calculating, the segments are simulated with computational fluid dynamics （CFD） method, then the approximate computational results about external flow field will be obtained. On the basis of the idea, the change of external flow field of wagon-shaped car at the moment of passing is simulated through solving three-dimensional, steady and uncompressible N-S equations with finite volume method. Numerical simulation analysis of side force coefficient, stream lines, body surface pressure distribution of wagon-shaped car are presented and a preliminary discussion of aerodynamic characteristics of correlative situations is obtained. Finally, the C3 -x/l curve of side force coefficient（C3） of car following relative distance （x/l） between cars is obtained. By comparison, the curve is coincident well with the experimental data, which shows creditability of numerical simulation methods presented.
文摘A new effective technique, useful in telecommunications industry for passing an optical telephone cord attached to a connector through pipeline,has been developed using the spiral flow. Using this technique, the cord could be passed through a straight pipeline 150 meters long and a roll of vinyl tube 50 meters long. However, under the same condition, the cord could not pass through when using the turbulent flow. To obtain a high speed stable spiral flow, a nozzle with an annular slit connected to a conical cylinder was used. A pressurized fluid with no tangential flow was supplied through this slit and the fluid, passing through the conical cylinder, was deformed into spiral flow with the steeper axial velocity distribution compared to that of turbulence pipe flow due to Coanda effect and instability. As a result, the cord was attracted to the axis area of the pipe, which effectively increased the ability for the work of cord passing. This high ability for cord passing is attributed mainly to the reduction of the friction made between the cord and the pipe wall, caused by the deformation to spiral flow.
文摘PROOS is a distributed operating system running on the computing nodes of massively parallel processing computer Dawning-1000. It is an efficient and easily extendible micro kernel operating system. It supports the intel NX message passing interface for communication.
