Experimental study of heat transfer on the rubber-cord cased pneumatic element surfaces under the natural convection

One of the ways of improving the calculations accuracy of the stationary objects and vehicles protection systems from vibrations and impacts is taking into account the influence of heat exchange processes with the environment occurring in the rubber-cord cased pneumatic elements and obeying Fourier's law of heat conduction and Newton's heat-transfer law. In the conducted study, the heat transfer coefficient values on the pneumatic element walls in the natural convection conditions are defined experimentally. The test bench, testing technique and used measuring instruments which are the heat flux sensors with the internal thermocouple are described. The heat transfer coefficient on the rubber-cord casing curved surface and on the metal flanges flat ones is found out to assume constant values being sufficient for practical application in the operating temperature range based on the process data. When applying the heat exchangers technical theory methods for the pneumatic elements calculation, it is acceptable to consider as a first approximation that the heat transfer coefficient has the identical values on all outer surfaces of the pneumatic element. (paper)