一般干线输气管都在阻力平方区The main pipelines are generally in the r...
未知题型一般干线输气管都在阻力平方区The main pipelines are generally in the resistance square area, 不满负荷时在混合摩擦区Under load in the mixed friction zone, 城市及居民区的配气管在水力光滑区。The air pipes of urban and residential areas are in the hydraulic smooth area.