螺旋风管的内壁绝对粗糙度
摘要：
通过回顾国内外关于螺旋风管摩擦阻力计算方法的相关文献,分析了气流在螺旋风管内与在直缝风管内的差异及其成因。用科尔布鲁克公式推导出了一种用实测数据反算螺旋风管内壁绝对粗糙度的公式,并根据用实测数据拟合得出的比摩阻计算式反算求出了部分管径螺旋风管的内壁绝对粗糙度。结果表明,螺旋风管的内壁绝对粗糙度并非是一个常数,而是管径和管内轴向平均风速的函数,甚至可为负数。
Abstract：
This article reviews the calculation methods of spiral duct friction loss in some Chinese and foreign literature, analyses the differences and reasons between the airflow in spiral duct and longitudinal seam duct. A formula for back-calculating the inner wall absolute roughness of spiral ducts using measured data is derived based on the Colebrook equation,and the inner wall absolute roughness of some diameters of spiral ducts is back-calculated by the friction factor calculation formula obtained by fitting with the measured data. The results show that the inner wall absolute roughness of spiral ducts is not a constant, but a function of the duct diameter and the axial average airflow velocity within the duct, and it can even be negative.
Keywords:spiral duct; longitudinal seam duct; friction loss; inner wall absolute roughness; measured data; duct joint spacing; spiral airflow; airflow velocity