圆管内定型湍流的流速分布规律

VELOCITY DISTRIBUTION LAW OF STEADY TURBULENT FLOW IN PIPE

目前通用的圆管内定型湍流的对数速度分布规律,存在两个主要揣点,一是在管中心处流速分布曲线产生尖角,二是用此规律得到的阻力系数λ值在Re<10~5时与莫迪图不符。这是由于认为在整个湍流核内切应力全等于管壁处的切应力所致,实际上切应力与距管中心的距离成正比。本文由此出发而导出湍流核内流速分布规律,从而消除了上述缺点。

There are two shortcomings in the common used logarithmic distribution law of the steady turbulent flow in pipe. Firstly, the velocity distribution curve is not smooth at the center of pipe. Secondly, The friction factor λ from this law at Re<10~5 is inconsistent with the Moody diagran, Boh are because of that the shearing stress at all turbulent region is misundrstood to be the same as well as that at the pipe wall. In fact the shearing stress is directly proportional to the vadius of pipe.Based on this, the velocity distribution law of the steady turbulent region is found in this paper.The shortcomings as above are eliminated by using this formula.