Louvre Head Loss
Calculates the pressure-drop loss coefficient and pressure drop across angled louvers (blinds) fitted inside a duct or pipe.
Reynolds Number
Re=νVDhwhere V is the mean flow velocity, Dh is the hydraulic diameter of the duct, and ν is the kinematic viscosity of air. For a square-section duct, Dh equals the side width.
Loss Coefficient
The loss coefficient has two parts — a geometric base term and a Reynolds-number-dependent turbulence correction:
K=K0+max(0,1−Re50)⋅kquWhen Re ≤ 50 the turbulence correction term is taken as zero (the factor is clamped).
The geometric base term is:
K0=(FAR1−FAR)2The angle-and-count coefficient kqu increases with louver angle θ and number of louvers n:
kqu=C(n)sin2θPressure Drop
Δp=K⋅21ρV2References
- Idel'chik, I.E. and Fried, E., Flow Resistance, a Design Guide for Engineers, Taylor & Francis, Washington D.C., 1989, p. 306.