Annotation: The article analyzes the energy potential of alternative sources of Ukraine. The projects using hydrogen technologies aimed at attracting solar energy to the infrastructure of energy technological complexes, in particular water desalination systems and for refueling automobile vehicles located in areas with high solar radiation potential, are considered. During the operation of water desalination plants using a solar power station as an energy source, contingencies are very likely to arise due to either a power outage (due to cloudy weather) or an emergency failure of individual elements of the system. In this case, it is required to ensure its removal from service without loss of technological capabilities (operability). For this purpose, it is necessary to provide for the inclusion in the technological scheme of the energy technological complex of an additional element that ensures operation of the unit for a given time, determined by the regulations for its operation. As such an element, a buffer system based on a hydrogen energy storage device is proposed. The current level of hydrogen technologies that are implemented in electrochemical plants developed at the Institute of Mechanical Engineering named after A. N. Podgorny of the National Academy of Sciences of Ukraine allows producing and accumulating the hydrogen under high pressure, which eliminates the use of compressor technology.

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 main directions of upgrading the pneumohydraulic systems are considered. Some methods of increasing their operability and reliability are analyzed.

Annotation: When accomplishing the task of spacecraft orbital injection, the necessity arises of main engine multiple ignitions and consequently, long pauses between the ignitions are possible. As the propellant during pauses between ignitions is in the conditions of practically full absence of gravitation and can freely move over entire tank volume taking practically any spatial position, to ensure main engine guaranteed ignition the necessity arises to move the propellant into pre-start position. The propellant is moved to the supply lines by way of creating longitudinal acceleration which is done using inertial continuity ensuring means (thrusters). The time of full liquid displacement from one position into another is the most important parameter having an impact on propellant amount in the tanks and accordingly, on power characteristics of a stage. The theoretical calculations of hydrodynamic processes are connected with considerable mathematical difficulties caused by complexity of solving hydrodynamic problems of determination of liquid flowing with free surface taking into account surface tension of the liquid and many other geometrical, kinematic, and dynamic factors. Therefore, the most reliable data from solving these problems are currently obtained only on model hydrodynamic stands where it is possible to model liquid behavior in tanks in the conditions of variable gravitation. The paper presents the authors-developed procedure of calculating the full time required for propellant components deposition during rocket’s apogee stage flight and the procedure of selecting the modeling parameters (scale, time, and acсeleration) to ensure development testing in the conditions of limited test stand base. The use of the proposed procedure allows (in initial phase of launch vehicle development) determining the full time required to perform deposition with sufficient accuracy and thus optimizing the propellant mass required for operation of inertial continuity ensuring system, which in its turn, will allow increasing the payload mass to be injected.