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导流条安放角度对管道车间断面螺旋流流速特性的影响

Influence of setting angle for guide bar on velocity characteristics of spiral flow in cross-sections between piped carriages

  • 摘要: 为分析筒装料螺旋流管道水力输送的能耗问题,该研究以导流条安放角为主要控制变量,采用理论分析与模型试验相结合的方法,研究了不同导流条安放角条件下管道车间断面的螺旋流流速特性。结果表明:不同导流条安放角条件下,管道车间断面的轴向流速分布趋势基本相同,均呈现先由管壁向内扩散,再由管轴线向外扩散的分布特征,且管道车间各断面轴向流速值整体较大,最大值达到3 m/s。不同导流条安放角下车间断面的径向流速基本在−1~1 m/s之间波动,且径向流速值为0的区域相对较大;随着导流条安放角度的增加,管道车间断面的径向流速逐渐呈现120°旋转对称分布,且在0°、120°与240°极轴方向上径向流速值较小。相较于轴向和径向流速,周向流速受导流条安放角的影响最大,且周向流速强度随导流条安放角的增大而增大,最大值能达到1.5 m/s。同时随着导流条安放角的逐渐增大,沿圆周断面呈逆时针旋转的周向速度增加;同径向流速类似,随着导流条安放角的增加,管道车间断面的周向流速也逐渐呈现120°旋转对称分布,但在0°、120°与240°极轴方向上周向流速值反而较大。该研究不仅完善了管道螺旋流理论,而且可为筒装料管道水力输送技术的推广应用提供理论参考。

     

    Abstract: This study aims to explore the velocity characteristics of spiral flow between piped carriages under various setting angles of the guide bar. A combined theoretical and simulation test was adopted, where the main control variable was set as the setting angle of the guide bar. The results showed that there was basically the same trend in the distribution of axial velocity at the section of two carriages in pipeline car under the different setting angles of the guide bar, where both spread inward from the pipe wall and then outward from the pipe axis. There was an overall large value of the axial velocity at each section of car carriages, with a maximum of up to 3 m/s. In the rear car, there was a positive or negative velocity of axial flow at the cross section, indicating the backflow occurred. The velocity values of water flow were basically positive at the section of the pipeline in the middle and front of the car. There was a gradual distribution of 120° rotation symmetry in both circumferential velocity and radial flow velocity at cross-sections between piped carriages with the increase in the installation angle of the guide bar. The value of circumferential velocity was larger, but that of radial velocity was smaller in the directions of 0°, 120°, and 240° polar axes. The intensity of circumferential velocity was much stronger as the setting angle of the guide bar increased, where the maximum circumferential velocity reached 1.5 m/s, indicating a great influence of setting angle on the circumferential velocity. Furthermore, the circumferential flow velocity was positive or negative, indicating two directions, including counterclockwise and clockwise. In percentage columnar accumulation, there was a stepladder characteristic of circumferential flow velocity under different setting angles of the guide bar. A positive correlation was found between the circumferential flow velocity and the setting angle of the guide bar. The radial velocity basically fluctuated between −1-1 m/s, where there was a relatively large area with zero. The radial flow velocity was also much smaller, compared with the axial and circumferential flow velocity. Two directions were found in the positive or negative radial flow velocity: inward and outward the circle center along the diameter. The finding can provide theoretical support for the spiral flow of pipelines and the popularization of piped hydraulic transportation.

     

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