Louver Pressure Drop

 

Louver Pressure Drop formula
\(  \Delta p \;=\;  \dfrac{ \rho }{ 2 } \cdot  \left(  \dfrac{ Q  }{ C_d \cdot A_c }  \right)^2 \)
Symbol	English	Metric
\( \Delta p \) = Louver Pressure Drop	\( lbf\;/\;in^2 \)	\( Pa \)
\( \rho \)  (Greek symbol rho) = Air Density	\( lbm\;/\;ft^3 \)	\( kg\;/\;m^3 \)
\( Q \) = Volumetric Flow	\( ft^3\;/\;sec \)	\( m^3\;/\;s \)
\( A_c \) = Louvre Core Area	\( in^2 \)	\( mm^2 \)
\( A_c \) = Discharge Loss Coeficient	\(dimensionless\)	\(dimensionless\)

Louver pressure drop is the reduction in fluid pressure that occurs as a fluid, such as air or gas, flows through a louver or a series of louvers.  It represents the energy lost due to the resistance created by the louvers' angled blades, which are designed to deflect or control the flow of the fluid. 

This pressure drop is a major factor in the design and operation of HVAC systems, air handling units, and industrial ventilation, as it directly impacts the system's efficiency and the power required by fans or pumps to maintain the desired flow rate.  A higher pressure drop means more energy is needed to push the fluid through the system.  The magnitude of the pressure drop is influenced by several factors, including the fluid's velocity, density, the louvre's design, blade angle, spacing, and the overall cleanliness of the louvre, as dirt and debris can increase resistance.  In essence, it's a measure of the aerodynamic resistance posed by the louver to the fluid moving through it.

When a fluid approaches a louver, its path is constricted and redirected by the angled blades.  This redirection causes a change in momentum and creates turbulent eddies, leading to a loss of kinetic energy and, consequently, a drop in static pressure.  This is governed by the principles of fluid dynamics, where the pressure drop is generally proportional to the square of the fluid velocity.  Therefore, even a small increase in airflow speed can significantly increase the pressure drop.  Engineers use this information to select the most efficient louvre designs and to size fans and other components appropriately to ensure the system operates effectively without excessive energy consumption.