# The ChE World

The Chemical Engineers' World
 Conversion | Geometry Formula | Chocked Flow | Chemical Properties Home | Contact Us | Sitemap Choked flow is a compressible flow effect. The parameter that becomes "choked" or "limited" is the mass flow rate. Choked flow is a fluid dynamic condition associated with the Venturi effect. When a flowing fluid at a given pressure and temperature passes through a restriction (such as the throat of a convergent-divergent nozzle or a valve in a pipe) into a lower pressure environment the fluid velocity increases. At initially subsonic upstream conditions, the conservation of mass principle requires the fluid velocity to increase as it flows through the smaller cross-sectional area of the restriction. At the same time, the Venturi effect causes the static pressure, and therefore the density, to decrease downstream past the restriction. Choked flow is a limiting condition which occurs when the mass flow rate will not increase with a further decrease in the downstream pressure environment while upstream pressure is fixed.Wikipedia

Choked/Unchoked Flow:

# Don't Use.

 Critical Pressure Ratio = \small \bold{\color{blue} R_{crit} = { \left ( \frac{2}{k+1} \right ) }^{ \frac{k}{k-1}}} k = Heat Capacity Ratio = Adiabatic Index = γ k usually in the range 1.09 to 1.67. \small \bold{\color{blue} k = \gamma = \frac{c_p}{c_v}} Inlet Pressure (in absolute Pa) = Pin Outlet Pressure (in absolute Pa) = Pout Flow is CHOKED or critical if \small \bold{\color{blue} R_{crit} \geq \frac {P_{out}}{P_{in}}} Flow is UNCHOKED or subcritical if \small \bold{\color{blue} R_{crit} < \frac {P_{out}}{P_{in}}}

Enter absolute inlet pressure and outlet pressure and heat capacity ratio (k) in below input boxes.

Pin Inlet Pressure (absolute Pa):
Pa
Pout Outlet Pressure (absolute Pa):
Pa

Heat Capacity Ratio (k):

Critical Pressure Ratio (Rcrit):

Absolute Pressure Ratio:

Under this condition, the flow is:

 \small \bold{\color{blue} \dot{m} = CA \ \sqrt[]{k \rho_{in} P_{in} { \left ( \frac{2}{k+1} \right ) }^{ \frac{k}{k-1}}} \ = \ CAP_{in} \ \sqrt[]{\left ( \frac{kM}{Z_{in} RT_{in}} \right ) { \left ( \frac{2}{k+1} \right ) }^{ \frac{k}{k-1}}} } \small {\color{black} \dot{m} } = mass flow rate, kg/s \small {\color{black} C } = discharge coefficient, dimensionless, usually 0.72. \small {\color{black} A } = discharge hole cross-sectional area, m2. \small {\color{black} \rho_{in}} = real gas (total) density at total pressure Pin and total temperature Tin, kg/m3. \small {\color{black} T_in } = absolute upstream total temperature of the gas, K. \small {\color{black} M } = gas molecular weight (dimensionless). \small {\color{black} R } = Universal Gas Law constant, (Pa.m3) / (kgmol.K) = 8.314472.103. \small {\color{black} Z_{in}} = the gas compressibility factor at Pin and Tin. Ideal gas Zin = 1.

To calculate the choke flow, please enter (C, A and ρin) or (C, A, M, Zin, and Tin)

 Discharge Coefficient (C): Hole Cross-sectional area (A): m2 Variable(s) to be inputed: ρin M, Zin and Tin Density at Pin and Tin (ρin) kg/m3 Molecular Weight (M): Compressibility Factor at Pin and Tin (Zin): Temperature(Tin): K

 Choked Mass Flow Rate (m): kg/s Choked Mass Flow Rate (m): kg/s All our online converters are free to use. We try to keep our software free of bugs and errors but we do not take any responsibility for any problems caused through the use of these calculators and converters. Units Converter | Complex Units Converter | Currency Converter | Date Converter | Geometry Formula | Universal Constants | Contact Us | Sitemap