Orifice Area

on . Posted in Flow Instrument

orifice area 1Orifice 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)

\( Q \;=\; A_o \; C_d \; \sqrt{ 2 \; G \; h_c }  \) 

\( C_d \;=\; Q  \;/\; A_o \; \sqrt{ 2 \; G \; h_c } \) 

\( G \;=\; ( Q \;/\; C_d \; A_o )^2  \;/\; 2  \; h_c  \) 

\( h_c \;=\; ( Q \;/\; A_o \; C_d )^2  \;/\;  2  \; G  \) 

Solve for Ao

orifice flow rate, Q
orifice discharge coefficient, Cd
orifice gravitational constant, G
orifice center of head, h

Solve for Q

orifice area, Ao
orifice discharge coefficient, Cd
orifice gravitational constant, G
orifice center of head, h

Solve for Cd

orifice flow rate, Q
orifice area, Ao
orifice gravitational constant, G
orifice center of head,h

Solve for G

orifice flow rate, Q
orifice area, Ao
orifice discharge coefficient, Cd
orifice center of head, h

Solve for h

orifice flow rate, Q
orifice area, Ao
orifice discharge coefficient, Cd
orifice gravitational constant, 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 \( dimensionless \)
\( G \) = orifice gravitational constant \(lbf-ft^2 \;/\; lbm^2\)  \(N - m^2 \;/\; kg^2\) 
\( h_c \) = orifice center of head \( in \) \( mm \)

 

Piping Designer Logo Slide 1

Tags: Area Orifice and Nozzle