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至今,层流等热流加热圆管进口段内同时求解温度与速度分布,一般假定速度边界层已充分发展和粘度μ为常数,而且大都采用积分方法。本文采用数值计算的方法,分别对μ=常数及μ=f(T)两种情况进行了计算,得到了各截面的、沿对称轴线上的速度和温度分布,以及速度边界层充分发展所需长度。计算结果与实验数据的符合程度是相当好的,计算表明μ随温度变化对结果影响显著。
Up to now, temperature and velocity distribution have been solved simultaneously in the inlet section of the heat flow tube, such as laminar flow. It is generally assumed that the velocity boundary layer has been fully developed and the viscosity μ is constant, and most of them adopt the integral method. In this paper, the numerical calculation method is used to calculate μ = constant and μ = f (T) respectively. The velocity and temperature distribution along the symmetry axis of each cross section are obtained, and the velocity boundary layer is fully developed length. The calculated results are in good agreement with the experimental data. Calculations show that μ varies significantly with temperature.