Gray correlation

Brief

• The boundary between the bubble and slug flow

Math & Physics

Following the law of conservation of energy the basic steady state flow equation is:

$144 \frac{\Delta p}{\Delta h} = \bar \rho_m + \rho_m \frac{f v_m^2 }{2 g_c D} + \rho_m \frac{\Delta{(\frac{v_m^2}{2g_c}})}{\Delta h}$

where

$\bar \rho_m = \rho_L H_L + \rho_g (1 - H_L)$ slip mixture density

$\rho_m = \rho_L C_L + \rho_g (1-C_L)$ no-slip mixture density

Colebrook–White equation for the Darcy's friction factor:

$\frac{1}{\sqrt{f}}= -2 \log \left( \frac { \varepsilon'} {3.7 D} + \frac {2.51} {\mathrm{Re} \sqrt{f}} \right)$

Reynolds two phase number:

$Re = 2.2 \times 10^{-2} \frac {q_L M}{D \mu_L^{H_L} \mu_g^{(1-H_L)}}$

Workflow

To find H_g calculate :

$N_V = 453.592\ \frac{{\rho_m}^2 {v_m}^4}{g_c \sigma_L (\rho_L - \rho_g)}$

$N_D = 453.592\ \frac{g_c (\rho_L - \rho_g) D^2}{\sigma_L }$

$R = \frac{v_{SL}}{v_{SG}}$

$B = 0.0814 \left ( 1 - 0.554\ \ln \left (1 + \frac{730 R}{R+1} \right ) \right )$

$A = -2.2314 \left ( N_V \left (1 + \frac{205}{N_D} \right ) \right )^B$

$H_g = \frac{1-e^A}{R+1}$

Nomenclature

NV velocity number