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圆角铣削动态切削力方向力系数的时变性研究
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作者 谢黎明 苏彩虹 +1 位作者 靳岚 芮执元 《组合机床与自动化加工技术》 北大核心 2016年第6期51-54,共4页
针对圆角铣削加工过程切削力不稳定问题,建立考虑再生颤振作用下的圆角铣削动态切削力模型,通过铣削过程中刀具相对于工件坐标的变化,推导切入、切出角随刀具角速度变化的计算公式,研究动态切削力的方向力系数的时变性问题,在仿真得到... 针对圆角铣削加工过程切削力不稳定问题,建立考虑再生颤振作用下的圆角铣削动态切削力模型,通过铣削过程中刀具相对于工件坐标的变化,推导切入、切出角随刀具角速度变化的计算公式,研究动态切削力的方向力系数的时变性问题,在仿真得到的颤振稳定性叶瓣图基础上,对圆角铣削在颤振条件下方向力系数的时变性处理的正确性进行验证,并分析了切削力系数及铣刀齿数对颤振稳定性的影响,为圆角铣削切削参数的选择提供了可靠依据。 展开更多
关键词 圆角铣削 颤振稳定性 动态切削力 方向力系数
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The Effect of Netting Solidity Ratio and Inclined Angle on the Hydrodynamic Characteristics of Knotless Polyethylene Netting 被引量:5
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作者 TANG Hao HU Fuxiang +3 位作者 XU Liuxiong DONG Shuchuang ZHOU Cheng WANG Xuefang 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第5期814-822,共9页
Knotless polyethylene(PE) netting has been widely used in aquaculture cages and fishing gears, especially in Japan. In this study, the hydrodynamic coefficient of six knotless PE netting panels with different solidity... Knotless polyethylene(PE) netting has been widely used in aquaculture cages and fishing gears, especially in Japan. In this study, the hydrodynamic coefficient of six knotless PE netting panels with different solidity ratios were assessed in a flume tank under various attack angles of netting from 0?(parallel to flow) to 90?(perpendicular to flow) and current speeds from 40 cm s^(-1) to 130 cm s^(-1). It was found that the drag coefficient was related to Reynolds number, solidity ratio and attack angle of netting. The solidity ratio was positively related with drag coefficient for netting panel perpendicular to flow, whereas when setting the netting panel parallel to the flow the opposite result was obtained. For netting panels placed at an angle to the flow, the lift coefficient reached the maximum at an attack angle of 50? and then decreased as the attack angle further increased. The solidity ratio had a dual influence on drag coefficient of inclined netting panels. Compared to result in the literature, the normal drag coefficient of knotless PE netting measured in this study is larger than that of nylon netting or Dyneema netting. 展开更多
关键词 panel fishing hydrodynamic Reynolds nylon polyethylene perpendicular Angle assessed aquaculture
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Flow Past an Accumulator Unit of an Underwater Energy Storage System: Three Touching Balloons in a Floral Configuration 被引量:3
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作者 Ahmadreza Vasel-Be-Hagh Rupp Carriveau David S-K Ting 《Journal of Marine Science and Application》 2014年第4期467-476,共10页
An LES simulation of flow over an accumulator unit of an underwater compressed air energy storage facility was conducted. The accumulator unit consists of three touching underwater balloons arranged in a floral config... An LES simulation of flow over an accumulator unit of an underwater compressed air energy storage facility was conducted. The accumulator unit consists of three touching underwater balloons arranged in a floral configuration. The structure of the flow was examined via three dimensional iso surfaces of the Q criterion. Vortical cores were observed on the leeward surface of the balloons. The swirling tube flows generated by these vortical cores were depicted through three dimensional path lines. The flow dynamics were visualized via time series snapshots of two dimensional vorticity contours perpendicular to the flow direction; revealing the turbulent swinging motions of the aforementioned shedding-swirling tube flows. The time history of the hydrodynamic loading was presented in terms of lift and drag coefficients. Drag coefficient of each individual balloon in the floral configuration was smaller than that of a single balloon. It was found that the total drag coefficient of the floral unit of three touching balloons, i.e. summation of the drag coefficients of the balloons, is not too much larger than that of a single balloon whereas it provides three times the storage capacity. In addition to its practical significance in designing appropriate foundation and supports, the instantaneous hydrodynamic loading was used to determine the frequency of the turbulent swirling-swinging motions of the shedding vortex tubes; the Strouhal number was found to be larger than that of a single sphere at the same Reynolds number. 展开更多
关键词 droplet-shaped bluff body LES swirling flow swinging flow shedding vortex tubes underwater balloons
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