Influence or Void and Flow Regime on Liquid Metal MHD Induction Generator Using Two-Phase Flow

In the present paper, the performance characteristics of a liquid metal MHD induction converter operated with two-phase mixture flow are treated experimentally and analytically in comparison with those with single-phase liquid flow as working fluid.

The experiments were performed with a flat-linear channel induction converter, through which NaK-N₂ two-phase mixture was made to flow at a velocity ranging 5–30m/sec, with a void fraction 0–50%.

Data were taken over the following range of non-dimensional parameters:

• Reynolds number: 3.3x10⁴–2.0x10⁵ (for liquid flow alone)

• Hartmann number: 12 (with magnetic field in r.m.s. and slip S = 1)

• Baroczy's property index: 0.0031–0.023 (for two-phase flow)

The electrical power output of the experimental generator showed a sudden decrease near 20% void fraction, which was attributed to change in the flow pattern, while the generator efficiency did not show such an abrupt drop, but decreased gradually with increase of the void fraction.

Coupling the electro-magnetic equations with the power law distribution for both fluid velocity and void fraction proposed by Bankoff, we have obtained numerically the performance characteristics of the liquid metal MHD induction converter operated with two-phase flow, which provided a quite satisfactory clarification of the results obtained experimentally.