Boiling crisis in porous structures

A hydrodynamic model of the boiling crisis in porous structures based on holographic interferometry and velocimetry has been developed, taking into account the liquid excess. The critical values of heat exchange surface height and structure thickness are established, the minimum value of hydrodynamic pressure that creates the required liquid surplus is determined. Two mathematical models of the boiling crisis involving internal boiling characteristics, revealed by means of velocity filming are proposed. The highest values of critical flows have been obtained for a dimensionless pressure of 4.4.10(-3), and its growth to the value of 0.44 has little effect on the change in the crisis situation. All three models for the boiling crisis agree well with experiment for a wide range of pressure changes (0.01 ... 8) MPa, with the effect of thermophysical properties derived from the models rather than by experimental selection of pressure. Three types of heat sources have been used in the experiments: electric, gas, and radiant, and the experiments have been completed by destroying heat-exchange surfaces and porous structures. Studies have been conducted on seven porous structures under the electric heating method and on eight other porous structures under gas heating for 26 combustion chambers and nozzles up to their destruction.

Automated summary

This study develops a hydrodynamic model of the boiling crisis in porous structures using holographic interferometry and velocimetry. Two mathematical models are proposed based on internal boiling characteristics revealed by velocity filming. The models agree well with experimental results for a wide range of pressure changes and different heat sources and porous structures.