๐จ Duct Sizing & Static Regain
Size circular and rectangular air ducts using Equal Friction and Velocity methods, with Colebrook-White friction, aspect ratio checks, and equivalent diameters.
โก Fortran 90 Engine
Double Precision (IEEE 754)
โ ISO / ASME Validated
Hvac
๐ Solver Telemetry
โ ACTIVE
๐๏ธ Views
19
โก Solves
17
๐พ Downloads
489
๐ฆ Fortran Code
4.4 KB
๐
Released
Jun 2026
โฑ๏ธ Latency
< 1 ms
๐จ HVAC Air Duct Flow Profile & Velocity Boundary Layer
Real-time visual simulation of rectangular & circular duct velocity streamlines๐ Configuration & Presets
๐ข Office Trunk (8000 mยณ/h)
๐๏ธ Hotel Quiet (3.5 m/s)
๐ณ Kitchen Hood (9 m/s)
๐ฅ Cleanroom (14k mยณ/h)
ASHRAE Duct Formulations:
โข Equivalent Diameter: De = 1.30 ยท (a ยท b)0.625 / (a + b)0.25
โข Friction Rate: ฮP/L = f ยท (ฯ vยฒ) / (2 De)
โข Velocity Pressure: Pv = ยฝ ฯ vยฒ [Pa]
โข Aspect Ratio: AR = max(a, b) / min(a, b) โค 4:1
โข Equivalent Diameter: De = 1.30 ยท (a ยท b)0.625 / (a + b)0.25
โข Friction Rate: ฮP/L = f ยท (ฯ vยฒ) / (2 De)
โข Velocity Pressure: Pv = ยฝ ฯ vยฒ [Pa]
โข Aspect Ratio: AR = max(a, b) / min(a, b) โค 4:1
๐ Sizing Results & Dimensions
Configure inputs and click Compute to view results.
๐ Calculation Methodology & ASHRAE Standards
Equal Friction & Huebscher Equivalence
The Equal Friction method maintains uniform pressure drop per unit length. The Huebscher formula computes rectangular ducts with equivalent flow capacity:
De = 1.30 ยท (a ยท b)0.625 / (a + b)0.25
Aspect Ratio & Noise Criteria
Rectangular ducts should maintain aspect ratio $AR \le 4:1$ to minimize sheet metal weight and prevent acoustic rumble generated by high velocity gradients.
Key Engineering Assumptions
- Standard air density $\rho = 1.204\,\text{kg/m}^3$ at $20^\circ\text{C}$ and $101.325\,\text{kPa}$.
- Galvanized steel absolute roughness $\epsilon = 0.09\,\text{mm}$.
- Standard commercial 25 mm dimensional increments applied for fabrication.