二维水翼型空化流的数值计算(英文)

In order to predict the effects of cavitation on a hydrofoil, the state equations of the cavitation model were combined with a linear viscous turbulent method for mixed fluids in the computational fluid dynamics (CFD) software FLUENT to simulate steady cavitating flow. At a fixed attack angle, pressure distributions and volume fractions of vapor at different cavitation numbers were simulated, and the results on foil sections agreed well with experimental data. In addition, at the various cavitation numbers, the vapor fractions at different attack angles were also predicted. The vapor region moved towards the front of the airfoil and the length of the cavity grew with increased attack angle. The results show that this method of applying FLUENT to simulate cavitation is reliable.     

粘流方法的螺旋桨尾流场数值分析(英文)

The computational fluid dynamics(CFD) method is used to numerically simulate a propeller wake flow field in open water.A sub-domain hybrid mesh method was adopted in this paper.The computation domain was separated into two sub-domains,in which tetrahedral elements were used in the inner domain to match the complicated geometry of the propeller,while hexahedral elements were used in the outer domain.The mesh was locally refined on the propeller surface and near the wake flow field,and a size function was used to control the growth rate of the grid.Sections at different axial location were used to study the spatial evolution of the propeller wake in the region ranging from the disc to one propeller diameter(D) downstream.The numerical results show that the axial velocity fluctuates along the wake flow;radial velocity,which is closely related to vortices,attenuates strongly.The trailing vortices interact with the tip vortex at the blades’ trailing edge and then separate.The strength of the vortex shrinks rapidly,and the radius decreases 20% at one diameter downstream.     

混合动力轨道车电传动系统

GCD-1000HJ型混合动力轨道车是一种以内燃机和动力电池为动力源的重型轨道车,该车为四轴电传动轨道车,具有内燃机牵引、动力电池牵引和混合牵引三种工作模式。该车具有空气制动和电阻制动两种制动方式,在电制动工况下,可将动能转化成电能给动力电池充电,实现能量回收利用,节约燃油。文章对GCD-1000HJ型混合动力电传动轨道车牵引主传动系统、辅助系统的构成和方案特点进行了详细的说明。     

运用周期性边界条件预报螺旋桨的敞水性能(英文)

Mathematical models of propellers were created that investigate the influence of periodic boundary conditions on predictions of a propeller’s performance. Thrust and torque coefficients corresponding to different advance coefficients of DTMB 4119, 4382, and 4384 propellers were calculated. The pressure coefficient distribution of the DTMB 4119 propeller at different sections was also physically tested. Comparisons indicated good agreement between the results of experiments and the simulation. It showed that the periodic boundary condition can be used to rationally predict the open water performance of a propeller. By analyzing the three established modes for the computation, it was shown that using the spline curve method to divide the grids can meet the calculation’s demands for precision better than using the rake cutting method.     

企业要上市？管理先上市

对于想做大做强的企业，上市无疑是一剂“补药”。然而“是药三分毒”，企业要上市，管理必须先上市!“管理上市”是企业以上市公司的管理要求规范自身的各项经营活动．以上市所必须的社会化、公开化、规范化、制度化为契机．实现管理规范化．提升自身管理能力和竞争力。     

基于SWOT分析法的铁路货运CRM对策

通过SWOT分析法,以六盘水车务段为背景,对其货运业发展的优势、劣势、机遇和威胁进行了客观分析;在此基础上找出货运业务的特点和重点,运用CRM相关知识,提出了4V营销、关系营销等新营销方式在货运业务中的应用方法和效果,以实现铁路货物运输的资源最优化和效益最大化.     

桨舵组合式节能推进器设计及水动力性能验证

为减小螺旋桨尾流能量耗散,提高桨舵系统的推进效率,开展桨舵组合式推进器设计研究。首先,基于适伴流设计思想结合面元法编制最大阻力减额的扭曲舵设计程序,获得桨后舵不同展向位置的扭曲角度,并通过与一前端削平的舵球及桨毂光顺连接形成桨舵组合式推进器的设计方案。然后,采用数值仿真分析获得均匀流场中桨舵组合式推进器的水动力性能、压力分布与流场特性等细节,初步验证设计方案的合理性。最后,开展船后桨舵组合式推进器的水动力性能试验,获得不同航速下螺旋桨和舵的水动力性能。试验结果表明,桨舵组合式推进器较原型桨舵推进器的效率在全航速段均有一定程度的提升,在设计工况点提升值达2.7%,证明设计方法正确,设计方案合理可行。