Method for measuring convective heat transfer coefficient

Abstract

The invention discloses a method for measuring a convective heat transfer coefficient; the method comprises the following steps of: finding out a theoretically calculated cooling curve with the best overlap ratio with an actually measured cooling curve based on comparison between the actually measured cooling curve of a sample to be measured in air and the theoretically calculated cooling curve of the sample to be measured in air; and taking the heat transfer coefficient corresponding to the theoretically calculated cooling curve as the convective heat transfer coefficient between the surface of the sample to be measured and the air. The method lays a foundation for obtaining thermal spontaneous combustion critical parameters of a solid propellant or an engine and guaranteeing the test safety. The method is simple in equipment and easy and convenient to operate, the surface heat exchange coefficient of the solid propellant under different conditions can be measured, and the method can also be popularized to measurement of the surface heat exchange coefficient of uniform materials such as liners, heat insulation layers, non-metal materials and metal materials in all directions under different environmental conditions such as water cooling, quenching and heat treatment.

Description

technical field [0001] The invention relates to the technical field of measurement methods, in particular to a method for measuring convective heat transfer coefficients. Background technique [0002] Solid propellants contain a large amount of active components such as oxidizers, explosives, and metal fuels, which will decompose and release heat under a certain temperature stimulus. If the heat emitted by the propellant cannot escape in time, once the heat accumulates, it will cause the propellant to decompose. Spontaneous combustion causes a safety accident. The thermal spontaneous combustion of propellant has obvious size effect. For a grain of certain shape, propellant size, heat production rate, thermal conductivity, specific heat capacity and surface heat transfer coefficient (heat transfer environment) will affect the heat accumulation effect of propellant and then affect Hot spontaneous combustion. Among these parameters, the propellant size is easier to measure, t...

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Problems solved by technology

Among these parameters, the propellant size is easier to measure, the heat production rate can be determined by thermal analysis methods (such as microcalorimetry, DSC method), etc., and the thermal conductivity and specific heat capacity are specified in the standard QJ809-94 "Composite Solid Propellant Thermal Conductivity and Specific Heat Capacity Determination Method—Quasi Steady State Method”, but there is no method for the surface heat transfer coefficient of the propellant to refer to

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