The influence of Laval nozzle throat size on supersonic molecular beam injection

In this study, finite element analysis （FEA） has been used to investigate the effects of different Laval nozzle throat sizes on supersonic molecular beam. The simulations indicate the Mach numbers of the molecular stream peak at different positions along the center axis of the beam, which correspond to local minimums of the molecular densities. With the increase of the throat diameter, the first peak of the Mach number increases first and then decreases, while that of the molecular number density increases gradually. Moreover, both first peaks shift progressively away from the throat. At the last part, we discuss the possible applications of our FEA approach to solve some crucial problems met in modern transportations.     

基于轴心位置监测的船用汽轮机组对中调整方法研究

为使机组的轴系对中状态处于一个较佳的状态,降低轴系不对中对机组振动噪声的影响,在分析了传统对中方法不足的基础上,提出了基于轴心轨迹监测的对中调整方法,该方法综合了考虑机组热态状态的轴承座变形、热胀等因素,可较为准确地反映机组热态运行下轴系的对中状态,实践证明该方法可为机组的热态对中调整起指导作用。同时,分析了其不足之处[其后应补充一些研究结论及意义],并指出后续还需进一步通过试验探索进行完善,以提高其应用精度。