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雷诺数对圆形渐缩喷嘴湍流射流的影响 总被引:2,自引:0,他引:2
The present study systematically investigates by experiment the influence of Reynolds number (Re) on a turbulent jet issuing from a smoothly-contracting round nozzle. Measurements were performed for seven Reynolds numbers varying from Re = 4,050 to Re = 20,100 using single hot-wire anemometry and over an axial distance of 30 nozzle exit diameters. Although all the exit velocity profiles are of "top-hat" shape, these measurements reveal significant dependence on Re of the exit and downstream flows. The effect of Re on both the mean and turbulent fields is substantial for Re < 10,000 and becomes weak beyond Re = 10,000. The length of the jet’s potential core and the far-field rates of decay and spread all depend significantly on Re. 相似文献
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基于PDA的GPS车辆监控系统 总被引:6,自引:0,他引:6
结合GPS、GIS、GPRS建立空间数据库,以及网络信息的传递以实现车辆监控。针对GPS与GIS集成中的一些关键技术进行研究:GPS信号是如何接受和处理、GPS信号点的地图匹配、车辆导航,实现监控中心和车辆之问的无线通信和信息交互,从而实现车辆的监控。 相似文献
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