The Lockhart–Martinelli parameter () 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:
- is the liquid phase mass flowrate;
- is the gas phase mass flowrate;
- is the gas density;
- is the liquid density.
- Lockhart, R.W., Martinelli, R.C.; Chem. Eng. Prog., Vol. 45. 1949, pp. 39–48