Universal orthometric real gas equation of state for modeling processes in rocket-and-space technology units

Abstract

A domain of the working parameters of the gas unified for all units of pneumatic automation, limited by isochore, adiabatic and two isotherms is formed. The requirements on the real gas equation suitable for dynamic calculations of these units areformulated. The known equations of state for real gas are analyzed and the reasons of their being not convenient to use are indicated. To obtain a new equation, it is proposed to use the theory of orthometric states of gas and the Boyle scales to measure its parameters. The form of the target equation is chosen and by using the standard tabular data the values of its three tuning coefficients are obtained. It turns out that nitrogen, argon, krypton, xenon, methane, oxygen, and air have the same two coefficients of the model, which result boosts the development of the theory of real gas. Similar equations are obtained for helium, xenon, krypton, and methane. It is shown that in the domain of gas working parameters all thermodynamic properties andcaloric characteristics follow from the equation of state, the formulas for calculating these functions are given. The calculated characteristics are compared with standard tabular data; the maximum of the compressibility factor error is 0.05...0.1 %. An improved compressibility equation for real gas in a cavity is deduced. Methods for solving algebraic equations for the density and temperaturearising at the phases of formation of initial conditions and at integration of the equations of compressibility and continuity are described. Directions of further development of the model and its practical applications are indicated.Для агрегатів пневмоавтоматики ракетної техніки визначена область зміни параметрів робочого тіла й сформульовані вимоги до рівняння стану реального газу, придатному для динамічних розрахунків цих агрегатів. Обрана ортометрична форма шуканого рівняння й отримані значення його настроювальних коефіцієнтів. Наведено формули для розрахунків термодинамічних і калоричних функцій, визначена похибка моделі. Отримано уточнене рівняння стисливості реального газу в порожнині. Зазначено напрямки подальшого розвитку моделі та її практичного застосування.