Annotation: During experimental investigation of the dynamic characteristics of a pneumatic test bench for testing liquid rocket engine high-flowrate automatic units, the effect was detected of 20-35% sound speed increase in the gas flow moving along the channel with corrugated wall (metal hose) which is a part of test bench drain system. The article presents the results of experiments and the task of theoretical justification of the effect is solved. It is indicated that its causes may be two mutually complementary factors – a decrease of gas compressibility at eddy motion and oscillations of metal hose wall. The physical model is considered that describes variation of gas elasticity and density in the conditions of high flow vorticity. It is supposed that in the near-wall layer of the channel, toroidal vortexes (vortex rings) are formed, which move into turbulent core of the flow where their size decreases and the velocity of rotation around the ring axis of torus increases. The spiral shape of the corrugation ensures also axial rotation, which increases vortexes stability. The intensive rotation around the ring axis creates considerable centrifugal forces; as a result, the dependence of pressure on gas density and the sound speed increase. The mathematical model has been developed that describes coupled longitudinal-lateral oscillations of gas and channel’s corrugated shell. It is indicated that in the investigated system, two mutually influencing wave types are present – longitudinal, which mainly transfer gas pressure pulses along the channel and lateral ones, which transfer the shell radial deformation pulses. As a result of modeling, it has been ascertained that because of the lateral oscillations of the wall, the propagation rate of gas pressure longitudinal waves (having the same wave length as in the experiments at test bench) turns out to be higher than adiabatic sound speed.

Annotation: The paper presents Yuzhnoye SDO experience in operating the workable models of rocket propellant vapors and water solutions thermal neutralization units. The processes going on in the thermal neutralization chamber are described. The neutralization unit design modernization is considered. The prospects for neutralization units improvement are defined.

Annotation: The paper considers the method of calculation of generative pressurization system for a tank with nitrogen tetroxide in which an attempt is made to model the temperature stratification of gas in the tank throughout the height of the tank. The applied physical model takes into account the impact of gas dynamic processes, heat-mass-exchange, and chemical reactions on gas parameters in the tank. The satisfactory convergence of the calculation results with the experimental data is shown.

Annotation: This article contains information on the calculation of the thermodynamic and translational properties of the gaseous xenon in the amount sufficient for the most engineering applications. The equation of state of xenon was obtained in dimensionless form, enabling calculations of the thermodynamic values using already known methods, developed for the air and other extensively used gases. An example is made on the implementation of the method based on this equation for calculation of the density, enthalpy and entropy of the gaseous xenon. The accuracy of calculation of these properties in the temperature range from 300 to 3000 K from 0,1 up to 120 MPa pressure was from 0,2 to 1,6%. Sufficiently accurate and simple dependencies were obtained for calculation of the enthalpy and heat of vaporization at the saturation line. Accuracy of the enthalpy calculation of the liquid xenon at the saturation line is not below 0,2%, the accuracy of the calculation of the heat of vaporization is not below 0,5%. New, simpler method, as compared to standard reference data, to calculate the translational properties (thermal conductivity, viscosity) of xenon at atmospheric pressure has been proposed. It is shown that thermal conductivity and viscosity can be calculated from the expression of the same type with different coefficients. Accuracy of the calculation of these properties using the proposed method is not below 2,2%. Considering the unsatisfactory test results of the well-known methods of calculation of the translational properties at high pressures, the effective method for approximating the table values of these properties has been proposed. In this case, at first, the temperature data at fixed pressures are approximated, then using these approximations, the values of the properties are calculated at the given temperature and various pressure values. After this, the value of the property is interpolated at the given high pressure. As an example of the implementation of this method, the Mathcad software for calculations of the thermal conductivity of gaseous xenon at high pressure is given. The materials of the article are intended for the specialists dealing with heat exchange processes.

Annotation: The general information on gas pressure reducers, on their purpose in launch vehicles and spacecraft pneumohydraulic systems is set forth. The impact of different operating conditions on physical characteristics of these devices is considered. The main and auxiliary parametric characteristics of the reducer are presented and the physical process of gas pressure reduction in it is explained. The error of output pressure regulation is evaluated using full differential of function, whose arguments (input pressure, flow rate, temperature) have scatter. The reducer temperature curve is shown and the impact of structural temperature on the value of dynamic (with flow rate) and static (without flow rate) pressure in reducer output cavity is explained. The difference between the excess pressure reducer and absolute pressure reducer is shown. The brief review of the designs of liquid and bimetal thermal compensators is presented, their advantages and disadvantages are described and the experience of reducers testing with regulating springs made of elinvar is analyzed. Attention is focused on operating temperature and its impact on stability of reducer adjustment. The formulas that describe thermodynamic processes occurring in the reducer are presented. Special attention is given to the properties of regulating spring of the reducer because of change of elasticity modulus coefficient at different temperatures, the expected pressure scatter at reducer output is evaluated and the necessity of measures to reduce this error is explained. To compensate for temperature disturbance, the formula of gas pressure in closed volume of sensitive element is derived. The essence of original technique of pneumocorrection of initial pressure in sensitive element cavity that was proposed and introduced on Yuzhnoye SDO-developed reducers is set forth.