ABOUT VALUES OF FRICTION FACTORS OF ENTRIES WITH LARGE CROSS-SECTIONS

The collection, analysis and generalization of practical data on the aerodynamic parameters of entries obtained during air-depression surveys were carried out. The average height of roughness was determined for entries with a cross-section of 10.0-16.0 m2 2 and roof bolting support technique. By calculation friction factor alpha were obtained for entries with the support technique and cross-section of 10.0 - 36.0 m(2). 2 Numerical modeling of the processes of air movement through entries with frame metal (arched) support was carried out. Based on the results, the minimum possible friction factors alpha were obtained for entries with a crosssection of 8.2 - 37.7 m(2). This friction factors actual for: a straight section of a clean (uncluttered) entry; uniform installation of support frames with distance between them of 0.31.2 m; no frame displacement relative to the entry axis.