Lockhart–Martinelli parameter

The Lockhart–Martinelli parameter ($$\chi$$) is a dimensionless number used in internal two-phase flow calculations. It expresses the liquid fraction of a flowing fluid. Its main application is in two-phase pressure drop and boiling/condensing heat transfer calculations.

It is defined as:



\chi = \frac{m_\ell}{m_g} \sqrt{\frac{\rho_g}{\rho_\ell}}, $$

where


 * $$m_\ell$$ is the liquid phase mass flowrate;
 * $$m_g$$ is the gas phase mass flowrate;
 * $$\rho_g$$ is the gas density;
 * $$\rho_\ell$$ is the liquid density.