充分發展圓管模型
圓形風管直管段壓力損失
計算直徑恆定之直圓形風管的分佈式壁面摩擦損失，需輸入流體密度、黏度與絕對粗糙度。過渡流與未建模管件不予推測。
直管段結果
一個 NREL/US DOE HVAC modelling presentation documents Darcy-Weisbach with laminar and turbulent friction-factor treatment. NASA defines Re=ρvL/μ as the inertial-to-viscous similarity parameter.
A NASA pipe-flow reference places transition usually between Re 2300 and 4000 depending on disturbances. No single regime equation is asserted in that interval, so this calculator reports it as out of scope. The DOE fluid-flow handbook notes viscosity is a fluid property affected by temperature.
已移除的聲稱： the former page hard-coded ρ=1.2 kg/m³ and μ=1.81×10⁻⁵ Pa·s without conditions, called a Haaland explicit approximation “Colebrook”, and applied it immediately above Re 2300. Unsourced roughness/velocity/equivalent-length presets and rectangular-duct shortcut were removed.
