Designing more sophisticated contemporary liquid rocket engines requires a precise understanding of the hydrodynamics in the blading sections of the pressurisation station, which is most often a turbopump. Friction loss in blade passages and outlets forms a significant proportion of all losses. The paper shows that it is necessary to account for the initial region of hydrodynamically unbalanced flow in the boundary layer, which is most characteristic of relatively short passages in blading sections of liquid rocket engine turbopumps. We performed the analysis required to select friction drag laws for components of pressurisation station blading sections. We considered and proposed a method for numerically integrating a system of equations to determine the variation in characteristic thickness of a spatial boundary layer and friction loss, accounting for the inertial component of the flow core velocity, depending on which flow modes occur in the components of pressurisation station blading sections in a liquid rocket engine. We show that it is necessary to correctly select the friction laws and to take the initial region into account so as to precisely determine the power parameters

Low thrust engines perform important functional tasks in control systems of motion, orientation and stabilization of spacecraft on various paths and space orbits. They are subject to high-reliability and long operating time in pulsed modes with a large number of starts. Bench tests of the engines are a special part of the program development of low thrust engines with high reliability and efficiency. The article analyses wave processes in hydraulic lines of test benches, which prevent obtaining reliable parameters and performances of engines during tests. Authors show that the exclusion of oscillation processes in test bench systems is the main condition for the organization and planning of tests. Similarity conditions for bench hydraulic lines of spacecraft propulsion systems are developed. A methodology for estimating the frequency responses of the bench lines during pulsed test modes is presented. Mathematical functions of geometric parameters of the bench hydraulic lines on the pulse responses of low thrust engines are obtained, allowing optimization of the bench propellant feeding system to avoid resonance oscillation processes. Research results provide reliable estimates of the parameters and reliability of low thrust engines.

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The research generates an integral relation of the energy equations for the temperature three-dimensional boundary layer allowing to integrate surfaces of any shape to determine thickness of energy loss. An equation to determine thickness of energy loss is necessary to specify heat transfer law and local heat transfer coefficients within boundary conditions of turbo machinery cavities.

The research elaborates the main characteristics of the liquid propellant engines; it determines that some turbo pump units have got the frequency of rotor spinning up to 100 000 and even 120 000 r.p.m. The authors analyse the current methodologies to specify losses connected with disc friction. The methodologies determining disc friction coefficient often obtain criterion-empirical character, and due to increasing a number of rotor spinning of turbo pump unit of the liquid propellant engines, they reflect the specification reliability inaccurately. The research demonstrates equations to determine disk friction coefficients based on considering the theory of three-dimensional boundary layer to a rotational flow taking into account the turbulent process of velocity distribution. The authors give recommendations on determining an index of velocity distribution degree depending on Reynolds rotation criterion of a disc and plug flow.