Аннотация:The main ways to improve the efficiency of power equipment are associated with an increase in the maximum temperature of the working fluid in the cycles of power plants. However, its value is limited by the strength of materials and the efficiency of cooling systems of the most heat-stressed elements of power plants. In connection with the growth of thermal stress level in the elements of the design of power plants and engines, there is a growing interest in the use of transpiration, screen, ablation and evaporative cooling methods.
From the standpoint of thermal physics the most promissing cooling method is transpiration or porous cooling. In this case, the coolant flows through an extremely branched network of internal microchannels, intensively cooling down the wall. Porous cooling has the highest theoretical efficiency, which is characterized by the difference of the coolant temperature at the outlet of the permeable wall to the temperature of its outer surface. Due to technological and operational difficulties, as well as uncertainties in theoretical aspects, these cooling methods have so far limited application, but they are the most promising for use in cooling systems of gas turbine blades, combustion chambers, afterburner nozzles and rocket engines.