🚪 Air Curtain Aerodynamics

Determine air curtain Foster Deflection Number (Dn), AMCA 220 aerodynamic sealing efficiency, doorway infiltration reduction, and heating/cooling energy saved.

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated

Hvac

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💾 Downloads 309 📦 Fortran Code 4.4 KB

📅 Released Jun 2026

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🚪 Overhead Air Curtain Planar Jet Barrier & Deflection

Real-time visual simulation of downward turbulent jet resisting outdoor thermal & wind infiltration

📝 Configuration & Presets

🛒 Supermarket (H=2.8m, 11.5 m/s) ❄️ Cold Storage (-20°C / +20°C) 🚛 Loading Dock (H=4.5m, 20 m/s) 🛍️ Retail Quiet (8.5 m/s)

📐 Doorway Dimensions & Nozzle

Door Height H [m]:

Door Width W [m]:

Nozzle Discharge Slot Width b₀ [mm]:

Discharge Jet Velocity v₀ [m/s]:

🌡️ Thermal Gradient & Wind Pressure

Outward Discharge Angle α [°]: Standard: 15° to 20° outward

Outdoor Cross Wind Speed [m/s]:

Indoor Temperature T_i [°C]:

Outdoor Temperature T_o [°C]:

AMCA 220 Formulations:
• Deflection Number: D_n = (ρ_i b₀ v₀² cos α) / [ g H² |ρ_o − ρ_i| + ½ C_p ρ_o v_w² H ]
• Sealing Efficiency: E_seal ≈ 70% to 85% in optimal range (0.15 ≤ D_n ≤ 0.40)
• Thermal Energy Saved: Q_saved = E_seal · ṁ_infilt · c_p · |T_i − T_o| [kW]

📊 Air Curtain Performance Results

📊 Output Summary
💾 Fortran Source

Aerodynamic Sealing Efficiency

E_seal = 75.0 %

⚠️ OVERPOWERED (Excessive Jet Spill & Turbulence)

D_n = 0.535

Thermal Energy Saved 21.19 kW 72291 BTU/h

Unprotected Infiltration 5,751 m³/h 3,385 CFM

Fan Electric Power Draw 0.04 kW COP_barrier = 211.9

Air Curtain Discharge Flow 1,928 m³/h 1.8m wide × 35mm

📈 Sealing Efficiency (%) vs Discharge Velocity

📉 Heating/Cooling Energy Saved (kW) vs Outdoor Temp

=================================================================
 THERMOFLUIDCALC — AIR CURTAIN AERODYNAMICS REPORT
=================================================================
Case Title                 : Commercial Retail Boutique Low-Noise Doorway
Doorway Dimensions (H x W) : 2.40 m x 1.80 m
Nozzle Slot / Velocity     : 35.0 mm / 8.50 m/s (Angle = 10.0°)
Indoor / Outdoor Temp      : 22.0 °C / 8.0 °C (ΔT = 14.0 °C)
Outdoor Cross Wind Speed   : 1.50 m/s
-----------------------------------------------------------------
Foster Deflection No (Dn)  : 0.5350
Aerodynamic Barrier Status : ⚠️ OVERPOWERED (Excessive Jet Spill & Turbulence)
SEALING EFFICIENCY (E_seal): 75.00 %
Unprotected Infiltration   : 5,751.3 m3/h (3,385 CFM)
Thermal Energy Saved       : 21.19 kW (72291 BTU/h)
Fan Power Consumption     : 0.04 kW (COP = 211.9)
=================================================================

📘 Calculation Methodology & AMCA 220 Standards

Foster Deflection Criterion

The Deflection Number $D_n$ compares the downward planar jet momentum against the opposing transverse forces of thermal buoyancy and wind pressure:

                    Dn = (ρi b₀ v₀² cos α) / [ g H² Δρ + ½ Cp ρo vw² H ]
                

Optimal Barrier Operation

When $0.15 \le D_n \le 0.40$, the air curtain reaches the floor with sufficient momentum to split cleanly, preventing up to 85% of conditioned air loss.

Key Engineering Assumptions

Standard planar turbulent turbulent jet expansion angle $\approx 14^\circ$.
Fan combined motor and aerodynamic efficiency $\eta = 60\%$.
Outward nozzle discharge angle $\alpha = 15^\circ$ to counteract inward draft.

ThermoFluidCalc Engineering Report