Design Calculations of the Limiting Characteristics of Heat Pipes for Cooling Active Phased Antenna Arrays

Abstract

The article provides an algorithm for calculating the limiting characteristics of heat pipes for cooling active phased antenna arrays at a given saturation temperature. The maximum transmitted power is determined taking into account the limitations of the heat pipes operation by the capillary limit, by boiling (transition to film boiling, boiling limit), by the sonic limit at which the speed of steam reaches the speed of sound (sonic limit), by the entrainment of droplets liquid coolant from the surface of the wick with a counter flow of steam (entertainment limit) and viscous limit, which is realized at low temperatures (viscous limit). It is shown that an increase in the thickness of the wick and its porosity may be necessary to increase the capillary limit of heat pipes, while an increase in the thickness of the wick increases the thermal resistance of the tube and, accordingly, can lead to overheating of the cooled elements. Based on the above algorithm, design calculations for two types of heat pipes have been carried out. The dependences of various limits of the heat pipe on the operating temperature are plotted. Based on the above algorithm, calculations were performed for two types of heat pipes.

Investigation of mechanical properties of composite materials reinforced with carbon fibers

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Application of the spherical indenter for determination of the elastic modulus of coatings

“…In the present paper a comparison of different indentation techniques of polymer coatings on steel substrates is carried out on the measurement results. Macro tests were previously conducted for the investigated coatings to determine the bending elastic modulus of coated steel substrates [7][8][9][10][11][12][13][14][15][16][17][18][19]. It was shown that the coatings, despite their small thickness, have a significant influence on the elastic properties of thin steel plate specimens.…”

Heat transfer from a constant heat source to the plate surface: An analytical solution

“…And in papers [34][35][36][37][38] various mechanical investigations of heat protective composite materials on the basis of both analytical and numerical methods are given. Analytical solutions of thermoelasticity problems are important, including the validation of numerical solutions [39][40][41][42][43][44][45][46][47][48]. In this paper, we propose an analytical solution to the thermoelasticity problem for a plate heated by a source with a constant heat input at one surface.…”