矩形:Q=1000 m³/h,v=4 m/s,长宽比 2 → A=0.07 m²,372.68×186.34 mm,D_eq≈283.86 mm 矩形。Q=1000 m³/h=0.2778 m³/s。A=Q/v=0.06944 m²。b=√(A/r)=0.1863 m,a=0.3727 m。D_eq=1.30·(a·b)^0.625/(a+b)^0.25≈0.2839 m(以代码为准)。{"result":"Duct sizing (rectangular). Q=0.28 m³/s, v=4 m/s → A=0.07 m². Rectangular 372.68×186.34 mm (14.67×7.34 in), aspect 2, equivalent diameter 283.86 mm.","metadata":{"input":{"shape":"rectangular","flowRate":1000,"flowUnit":"m3/h","velocity":4,"aspectRatio":2},"result":{"shape":"rectangular","flowRate_m3_s":0.28,"velocity_m_s":4,"area_m2":0.07,"width_m":0.37,"height_m":0.19,"width_mm":372.68,"height_mm":186.34,"width_in":14.67,"height_in":7.34,"aspectRatio":2,"equivalentDiameter_m":0.28,"equivalentDiameter_mm":283.86,"equivalentDiameter_in":11.18}}}
圆形:Q=500 CFM,v=5 m/s → A=0.05 m²,D≈245.13 mm 圆形。Q=500 CFM=500·0.000471947=0.23597 m³/s。A=Q/v=0.23597/5=0.04719 m²。D=√(4A/π)≈0.2451 m≈245.13 mm(以代码为准)。{"result":"Duct sizing (circular). Q=0.24 m³/s, v=5 m/s → A=0.05 m². Diameter D=245.13 mm (9.65 in).","metadata":{"input":{"shape":"circular","flowRate":500,"flowUnit":"CFM","velocity":5},"result":{"shape":"circular","flowRate_m3_s":0.24,"velocity_m_s":5,"area_m2":0.05,"diameter_m":0.25,"diameter_mm":245.13,"diameter_in":9.65}}}