The article deals with the static calculations in designing a high-performance fixed fluid power drive with a single positive-displacement hydraulic motor. Designing is aimed at using a drive that is under development and yet unavailable to find and record the minimum of calculations and maximum of existing hydraulic units that enable clear and unambiguous performance, taking into consideration an available assortment of hydraulic units of hydraulic drives, to have the best efficiency.

The specified power (power, moment) and kinematics (linear velocity or angular velocity of rotation) parameters of the output element of hydraulic motor determine the main output parameters of the hydraulic drive and the useful power of the hydraulic drive under development. The value of the overall efficiency of the hydraulic drive enables us to judge the efficiency of high-performance fixed fluid power drive.

The energy analysis of a diagram of the high-performance fixed fluid power drive shows that its high efficiency is achieved when the flow rate of fluid flowing into each cylinder and the magnitude of the feed pump unit (pump) are as nearly as possible.

The paper considers the ways of determining the geometric parameters of working hydromotors (effective working area or working volume), which allow a selection of the pumping unit parameters. It discusses the ways to improve hydraulic drive efficiency. Using the principle of holding constant conductivity allows us to specify the values of the pressure losses in the hydraulic units used in noncatalog modes. In case of no exact matching between the parameters of existing hydraulic power modes and a proposed characteristics of the pump unit, the nearest to the expected characteristics is taken as a working version.

All of the steps allow us to create the high-performance fixed fluid power drive capable of operating at the required power and kinematic parameters with high efficiency.

In all high-vacuum mechanical pumps, namely molecular and turbo-molecular there is a need in sealing of inputs of the movement. A dynamic seals type find a wide application in modern industry. Protective properties and optimization of the dynamic seals at the stage of design become a relevant topic to be researched.

The aim of the work is to develop a mathematical model of gas flow in the face gap between two rotating disks. In building this model, the following assumptions are introduced: molecular gas flow, full exchange of momentum in collisions of molecules with disk surface, reflection of particles from the wall submits to the law of diffuse reflection, distribution of gas molecules according to the thermal motion speeds being described by Maxwell`s law. The calculation is based on the use of Monte Carlo method (method of test particle), which consists in the statistical modeling of processes. The article describes an algorithm to construct a mathematical model step by step. The trajectory of each molecule movement is traced from the moment of its moving in till its moving out of the system. The article defines both a probability for gas molecules to pass through the face gap of disk vacuum pump in forward and backward direction and a conductivity of the gap.

A numerical experiment based on the developed program has been conducted with considering the movement of the required number of molecules to provide a sufficient accuracy of calculation. Gas flow in the face gap of disk vacuum pump is studied. As a result of the experiment it was found that geometrical parameters of the gap and speed of disk rotation have an impact on the conductivity. With raising speed of disk rotation the probability for particles to pass in forward direction increases, accordingly increasing the conductivity, and for particles to pass in backward direction it decreases thereby improving the vacuum properties of the pump. The work carries out a process adequacy test based on the equality of the conductivity of the forward and reverse passages with disks being stationary. The accuracy does not exceed a tolerance. Results and, accordingly, recommendations, given in the article, can be used in designing a flow passage of the disk vacuum pumps, for providing a movement in high-vacuum mechanical pumps, and in calculating the overflows in the flowing passages of a similar pump design.

In design and operation of the hydraulic drive a with throttle control it is necessary to know the relationship between the pressure drop in the throttle controller and the flow of the working fluid flowing through it. To define this relationship it is necessary to know the area of hole at the throttling channel inlet and the value of flow rate.

Experience shows that manufacturing process capabilities disable us to provide a completely circular hole at the inlet of a cylindrical throttle channel and exclude having a chamfer. In this case, it is impossible to use a direct method to measure the actual design value of the area obtained as a result of manufacturing the throttle channel. The paper proposes the indirect method to determine a design area. The method is based on the fact that the flow rates at the same Reynolds number, lying in the zone of self-similarity, with fluid flow through the cylindrical channel having a circular cross section in separated state are equal to the flow rate of a sharpedged hole in the thin wall.

In order to assess the correctness of the indirect method are experimentally studied throttle device models with cylindrical throttle channels of different geometric dimensions and models with a sharp-edged hole in the thin wall.

The experimental studies have found that for models with cylinderical throttle channels, design values of the inlet area received by indirect method lie between the values of the area determined by direct measurement of the outer and inner diameters of the chamfer. Graphs of the flow rate as a function of the Reynolds number obtained from the experimentally determined dependence of the flow on the available head and taking into account the value of the hole areas defined by an indirect method coincided for all models with the cylinderical throttle channels and for the model with a circular hole in a thin wall in the range of Reynolds numbers from 104 до 106 .

The assessment results allow us to draw a conclusion that the indirect method to determine the design area of the throttle channel inlet is correct and recommend this method for practical use.

The article describes the features of numerical simulation of acoustic oscillation excitation in the resonators with a foam insert (regenerator) to study the excitation of thermo-acoustic oscillations in the circuit of small-sized engine model on the pulse tube.

The aim of this work is the numerical simulation of the emerging oscillations in thermoacoustic engine resonator at the standing wave. As a basis, the work takes a thermo-acoustic resonator model with the open end (without piston) developed in DeltaEC software. The precalculated operation frequency of the given resonator model, as a quarter of the wave resonator, is ν = 560 Hz.

The paper offers a simplified finite element resonator model and defines the harmonic law of the temperature distribution on regenerator. The time dependences of the speed and pressure amplitude for the open end of the resonator are given; the calculated value of the process operating frequency is approximately equal to the value of the frequency for a given length of the resonator. Key findings, as a result of study, are as follows:

1. The paper shows a potential for using this ESI-CFD Advanced software to simulate the processes of thermal excitation of acoustic oscillations.

2. Visualization of turbulent flow fluctuations in the regenerator zone extends the analysis capability of gas-dynamic processes.

3. Difference between operating frequency of the process simulated by ESI-CFD Advanced and frequency value obtained by analytical methods is about 4%, which is evidence of the model applicability to study the acoustic parameters of thermo-acoustic transducers. Experimental results have proved these data.

The paper dwells on the features of the chemical composition and structure of alloys based on Ni3Al. It examines the effect of heat treatment on the structure and phase parameters and on the short-term strength of the intermetallic VKNA-1B alloy.

Smelting bar stock was made by technique of vacuum induction. A directional solidification method was used to provide heat treatment of samples on the UVNS-4 installation.

The heat treatment was performed in the following modes: heating to a temperature of 1200, 1290, 1300 ° C, holding for 100, 4, 4 hours, respectively, furnace cooling to 800 ° C, then air-cooling. For heating was used the batch furnace VEBK S 400/100 with a maximum operating temperature of 1350 ° C. Samples were loaded in the furnace at 800 0C.

The phase composition of the VKNA-1B alloy was examined through physicochemical analysis based on electrochemical insulating phases in different electrolytes. The composition and quantity of the isolated phases were determined by the results of X-ray and chemical analysis methods.

To analyse the microstructure was used a scanning electron microscope JSM-840. In original cast state the VKNA-1B alloy has a cellular-dendritic structure. In the axes of the dendrites there is a γ'-phase (~ 75-80% vol.) surrounded by a viscous γ-phase in the form of thin layers; in the inter-dendritic regions there are large particles of γ'-phase. The increasing temperature of heat treatment comes with coarsening γ'-phase particles in inter-dendritic regions and, essentially, has no effect on the phase composition of the alloy. Results of mechanical tensile tests have shown that the alloy retains high strength values after long-term exposure and the increasing cell size of γ'-phase in the axes of the dendrites when raising the temperature leads to an increase in short-term strength of the alloy.

An electric drive of work rolls of the single-stand rolling mill duo-160 located in the laboratory of Bauman Moscow State Technical University (BMSTU) is selected as an object of the theoretical study. After the work rolls have gripped the work-piece the torsional vibrations occur in the drive; a 5-mass dynamic model is built to determine their forms and frequencies. Equations of torsionalvibration movement of masses with time are based on the Lagrange equations of type II. The paper identifies intrinsic moments of inertia and angular stiffness of parts and units of the electric drive. The graphs of the moments of elastic forces are built taking into consideration the dampers and backlashes. A revealed transition process has shown that given amplitudes of the cyclic shear stresses arising in dangerous section of the most loaded top spindle do not exceed the limit of its endurance in this section. In case of excess revealed, it would lead to accumulation of fatigue damage in the spindle metal and to formation of fatigue crack that most probably would appear near the shaft surface rather than in the metal mass. With further using the electric drive this micro-crack would be gradually evolved into macro-crack, the working cross-sectional area of the shaft would be reduced so that there would be a spindle failure and on the surface of a fatigue fracture of its shaft a strongly marked crack growth zone and a completely broken zone would be observed.