The article "Scale effect features during simulation tests of 3D printer-made vane pump models" discusses the influence of scale effect on translation of pump parameters from models, made with 3D-prototyping methods, to full-scale pumps. Widely spread now 3D-printer production of pump model parts or entire layouts can be considered to be the main direction of vane pumps modeling. This is due to the widespread development of pumps in different CAD-systems and the significant cost reduction in manufacturing such layouts, as compared to casting and other traditional methods.

The phenomenon of scale effect in vane hydraulic machines, i.e. violation of similarity conditions when translating pump parameters from model to full-scale pumps is studied in detail in the theory of similarity. However, as the experience in the 3d-printer manufacturing of models and their testing gains it becomes clear that accounting large-scale effect for such models has a number of differences from the conventional techniques. The reason for this is the features of micro and macro geometry of parts made in different kinds of 3D-printers (extrusive, and powder sintering methods, ultraviolet light, etc.).

The article considers the converting features of external and internal mechanical losses, leakages, and hydraulic losses, as well as the specifics of the balance tests for such models. It also presents the basic conversion formulas describing the factors affecting the value of these losses. It shows photographs of part surfaces of models, manufactured by 3D-printer and subjected to subsequent machining. The paper shows results of translation from several pump models (layouts) to the full-scale ones, using the techniques described, and it also shows that the error in translation efficiency does not exceed 1.15%. The conclusion emphasizes the importance of the balance tests of models to accumulate statistical data on the scale effect for pump layouts made by different 3D-prototyping methods since their conversion factors may vary.

The problem of capsizing object, which are free-supported under the forces of gravity, elasticity, friction, and other unpredictably changing external influences, is a global challenge for the civil engineering and for transport (air, road, rail, and others). Much of the research activities on capsizing the free-supported objects of the certain types are fragmentarily included in the different subject areas of technical applications. In particular, it is typical for a hydrotank that is a thin-walled shell-type liquid-filled container. The hydrotank problems are multiple structural, geometric and natural forms of nonlinearity. The aim of this study is to determine the phase and the critical parameters of the basic objects of simple shape with different supporting plane: cube; box; cylinder etc., pouring the fluid, with or without shell. Hydrotank capsize as a solid body with a fluid is analysed and as a first approximation this analysis precedes the assessment of stability of the object as a hydroelastic system. The experimental results prove the possibility to design, manufacture and use this type of hydrotanks to test underwater robots. The work gives more undestanding on the studied problem and on the sphere wherein results can be efficiently implemented.

The article describes a new design of the primary pump to run in powerful units (more than 1 GW) of power plants. The new construction has some advantages such as compactness, theoretical lack of radial and axial forces, and high efficiency in a wide range of flow. The abovementioned advantages can be possible owing to applying an innovative shape of the pump flow path. An impeller with the guide vanes forms the three-row single stage in the each row axial double entry blade system. The inlet and outlet parts have a shape of the involute that can ensure (according to calculated data) the efficiency and stability in a wide range of flow because of a lack of the spiral parts. The results of numerical calculations of the pump working flow theoretically confirm that demanding parameters of the pump (H=286 m; Q=1,15 m3 /s) can be obtained with competitive efficiency. To verify the proposed advantages of the construction, there was decision made to conduct the real physical experiment. For this purpose the small model of a real pump was designed with parameters H=14 m, Q=13 l/s. Construction of the pump model has a cartridge conception. In addition, there is a possibility for quick replacement of the some parts of the blade system in case of operational development of the pump. In order to obtain hydraulic characteristics of the pump to say nothing of the electromotor the torque gauge coupling is used. Numerical calculations for the pump model were also performed which confirm the operability. For manufacturing of the blade system the new perspective technology is applied. The main hydraulic components (impellers and guide vanes) are made of ABS plastic by using 3D-printer. According to this technology parts are made layer by layer by means of welded plastic filament. Using this method the satisfactory tolerance (approximately ±0,3 mm) of the parts was obtained. At that moment, it is possible to create the parts with the maximum size no higher than 150 mm. Immersing finished parts in acetone vapor enable us to increase the surface strength and reduce roughness. At this stage of the work some plastic parts are ready for assembling operation. Now manufacturing of other plastic parts of the blade system is under way along with pre-production of the rotor and stator components.

The paper considers some compact wedge-profiled seals for shafts and flanges of hydraulic machines made from light and durable material. Studies of the narrow-edged metal seals show that high tightness can be obtained with a minimum width of the contact. Under the high pressure of working fluid on the cylindrical surface, the compact wedge-profiled seals sag and completely adhere to the cones of seats, with ends slipping across the flat surfaces with no loss of integrity. The hollow portion available in the elastic characteristic enables us to reduce the contact stress (pressure) when compact wedge-profiled seals are used in movable joints, reducing friction and their wear.

The article presents the research results aimed at theoretical justification of requirements for automatic adaptive control systems (AACS) to be the basis of developed intelligent transmissions of multi-drive wheeled all-terrain vehicles.

To conduct studies was used a specially developed mathematical model of motion of triaxial all-wheel drive vehicle “Gidrohod-49061”, equipped with CVT full flow hydrostatic transmission (HST) on a non-deformable support surface. This mathematical model is to simulate different operating conditions of the vehicle, which are a consequence both of disturbances from the road and of control actions from the driver and AACS.

The article presents some results of theoretical and experimental studies to prove the adequacy of the developed mathematical model.

The results analysis of mathematical modeling proved conclusively that one of the main tasks to be solved owing to developed AACS of intelligent transmission of multi-drive wheeled vehicle is to reduce the mismatch value in operation of drive wheels.

It is shown that the reasons for these mismatches can be either AACS error when processing control signals or other factors that characterize operating conditions of the drive wheels. Therefore, the paper proposes to develop a tracking control system of HST of the considered vehicle using the output parameters characterizing operation conditions of its drive wheels rather than the values of control parameters of hydraulic working volumes. As output parameters, it is proposed to use the speed of the drive wheels (hydro-motor shafts) and pressure drop in the main pump hydraulic drives, coming to HST.

Therefore it is proposed to develop HST AACS of the vehicle under consideration, as a system of two-level regulation, including the kinematic (main level) and power (level of correction) circuits. The former provides, at the first approximation, the required values of the drive wheel speeds in the given conditions, and the latter, within the dead zone of the former, seeks to provide the optimum torque distribution to the wheels in these conditions.

The article presents main design and structure principles of pumping stations. It specifies basic requirements for the favorable hydraulic operation conditions of the pumping units. The article also describes the designing cases, when computational modeling is necessary to analyse activity of pumping station and provide its reliable operation. A specific example of the large pumping station with submersible pumps describes the process of computational modeling of its operation. As the object of simulation was selected the underground pumping station with a diameter of 26 m and a depth of 13 m, divided into two independent branches, equipped with 8 submersible pumps. The objective of this work was to evaluate the effectiveness of the design solution by CFD methods, to analyze the design of the inlet chamber, to identify possible difficulties with the operation of the facility. In details are described the structure of the considered pumping station and applied computational models of physical processes. The article gives the detailed formulation of the task of simulation and the methods of its solving and presents the initial and boundary conditions. It describes the basic operation modes of the pumping station. The obtained results were presented as the flow patterns for each operation mode with detailed explanations. Data obtained as a result of CFD, prove the correctness of the general design solutions of the project. The submersible pump operation at the minimum water level was verified, was confirmed a lack of vortex formation as well as were proposed measures to improve the operating conditions of the facility. In the inlet chamber there are shown the stagnant zones, requiring separate schedule of cleaning. The measure against floating debris and foam was proposed. It justifies the use of computational modeling (CFD) for the verifying and adjusting of the projects of large pumping stations as a much more precise tool that takes into account all the features of the object compared to the empirical formulas.