Orifice Area

Orifice area refers to the area cross-section of an orifice, which is a small opening or hole through which fluid flows.  The orifice area is an important parameter in fluid dynamics and flow calculations, particularly in applications such as pipes, nozzles, and valves.

• Geometric Orifice Area (GOA)  -  The orifice opening
• Effective Orifice Area (EOA)  -  The minimal cross-section area of the downstream jet.
• Contraction Coefficient (\(C_c\))  -  The ratio of the area measured at the vena contracta (EOA), to the area of the orifice (GOA) or \(C_c = EOA \;/\; GOA\)
• Discharge Coefficient (\(C_d\))  -  The ratio of actual flow to ideal flow or \(C_d = Q_a \;/\; Q_i\)

 

Orifice Area formula
\( A_0 \;=\; Q  \;/\; C_d \; \sqrt{ 2 \; G \; h_c }  \)     (Orifice Area) \( Q \;=\; A_o \; C_d \; \sqrt{ 2 \; G \; h_c }  \)  \( C_d \;=\; Q  \;/\; A_o \; \sqrt{ 2 \; G \; h_c } \)  \( G \;=\; ( Q \;/\; C_d \; A_o )^2  \;/\; 2  \; h_c  \)  \( h_c \;=\; ( Q \;/\; A_o \; C_d )^2  \;/\;  2  \; G  \)
Symbol	English	Metric
\( A_o \) = Orifice Area	\( in^2 \)	\( mm^2 \)
\( Q \) = Orifice Flow Rate	\(ft^3 \;/\; sec\)	\(m^3 \;/\; s\)
\( C_d \) = Orifice Discharge Coefficient	\( dimensionless \)	\( dimensionless \)
\( G \) = Orifice Gravitational Constant	\(lbf-ft^2 \;/\; lbm^2\)	\(N - m^2 \;/\; kg^2\)
\( h_c \) = Orifice Center of Head	\( in \)	\( mm \)