COMBINED TECHNOLOGIES FOR MANUFACTURING PARTS IN SOLID ELECTROLYTES

Рассмотрены вопросы изготовления открытых и полуоткрытых полостей в труднообрабатываемых деталях путем использования твердого электролита, наносимого на заготовку перед установкой удаляемой вставки. Показаны особенности протекания процесса анодного растворения припуска при статическом состоянии рабочей среды. Такие исследования выполнены впервые. Разработаны и проверены на практике изготовления типовых деталей режимы обработки для реализации процесса. Показано, что твердые электролиты имеют перспективы для дальнейшего использования при проектировании технологических процессов изготовления сложнопрофильных изделий из металлических труднообрабатываемых материалов, в том числе внедряемых на создаваемых образцах ракетно-космической техники. Они расширяют технологические возможности комбинированных методов, в которых одним из воздействующих факторов является электрическое и электромагнитное поле с высокой концентрацией мощности в импульсе. Впервые достигнута возможность разделять сборочные единицы путем образования зазора между сопрягаемыми деталями без доступа в зону обработки жидкой рабочей среды, определяющей возможность локального съема припуска в месте сопряжения и удаления слоя материала, достаточного для разборки узлов. Заложены основы использования для нанесения твердого электролита аддитивных технологий путем наращивания равномерных слоев перед сборкой изделия. Предлагаемая технология перспективна для изготовления сборных конструкций с ограниченным доступом инструмента в зону выполнения операции. Кроме того, новая технология может успешно применяться в процессе ремонта машин We considered the issues of manufacturing open and semi-open cavities in difficult-to-machine parts by using solid electrolyte applied to the workpiece before installing the removable insert. We show the features of the process of anodic dissolution of the allowance at a static state of the working medium. Such studies have been performed for the first time. We developed and tested in practice the processing modes for the implementation of the process for the manufacture of standard parts. We show that solid electrolytes have prospects for further use in the design of technological processes for the manufacture of complex-profile products from metal hard-to-machine materials, including those introduced on the created samples of rocket and space technology. They expand the technological capabilities of combined methods, in which one of the influencing factors is an electric and electromagnetic field with a high concentration of power in a pulse. For the first time, the ability to separate assembly units by forming a gap between mating parts without access to the processing zone of a liquid working medium has been achieved, which determines the possibility of local removal of the allowance at the mating point and removal of a layer of material sufficient for disassembling the units. We laid the foundations for the use of additive technologies for applying solid electrolyte by building up uniform layers before assembling the product. The proposed technology is promising for the manufacture of prefabricated structures with limited tool access to the operation area. In addition, the new technology can be successfully applied in the process of car repair

Boosting engine performance with Bose-Einstein condensation

At low-temperatures a gas of bosons will undergo a phase transition into a quantum state of matter known as a Bose-Einstein condensate (BEC), in which a large fraction of the particles will occupy the ground state simultaneously. Here we explore the performance of an endoreversible Otto cycle operating with a harmonically confined Bose gas as the working medium. We analyze the engine operation in three regimes, with the working medium in the BEC phase, in the gas phase, and driven across the BEC transition during each cycle. We find that the unique properties of the BEC phase allow for enhanced engine performance, including increased power output and higher efficiency at maximum power.

Particularity of Heat Exchange of Twisted Heat Exchangers in External Flow

Perfecting the existing technologies and developing new ones require to rethink the processes in order to obtain qualitatively new results. Widespread use of cryogenic engineering in the chemical industry and medicine calls for a thorough analysis of both the efficiency of thermodynamic cycles and the hardware design of appropriate equipment. The power necessary to obtain low working medium temperatures is distributed between the cooling of the object and the losses in the various elements of the cryogenic setup. One of the best ways to increase the efficiency of the setup is to use the cold energy recovery. This is done by using various designs of recuperative heat exchangers, such as twisted heat exchangers. Existing methods of calculating the parameters of power equipment are based on empirical dependencies, which require some justification and clarification in order to be used for calculating cryogenic equipment parameters. The article describes the experimental setup, presents the research methods applied and analyses the results of the study on convective heat transfer in external flow past the tubular surface of the twisted heat exchanger. The obtained results for the laminar gas flow mode at Re < 2300 allowed determining the length of the initial heat section depending on the regime parameters of the contact phases and the geometric specifications of the twisted heat exchanger. The obtained dependence will make it possible to refine the method of calculating the parameters of the twisted heat exchanger in the annular channel.

Investigation of dynamic processes in pressure measurement systems for gas-liquid media

Initial-boundary value problems for systems of differential equations are considered, which are mathematical models of the mechanical system "pipeline - pressure sensor". In such a system, to mitigate the effects of vibration accelerations and high temperatures, the sensor is located at a certain distance from the engine and is connected to it via a pipeline. The "pipeline - pressure sensor" system is designed to measure pressure in gas-liquid media, for example, to control the pressure of the working medium in the combustion chambers of engines. On the basis of the proposed models, the joint dynamics of the sensitive element of the pressure sensor and the working medium in the pipeline is studied. To describe the motion of the working medium, linear models of fluid and gas mechanics are used, to describe the dynamics of a sensitive element, linear models of the mechanics of a deformable solid are applied. Analytical and numerical methods for solving initial-boundary value problems under study are presented. The numerical study of the initial-boundary value problem was carried out on the basis of the Galerkin method. In analytical study using the introduction of averaged characteristics, the solution of the original two-dimensional problem is reduced to the study of a one-dimensional model, whose further study made it possible to reduce the solution of the problem to the study of a differential equation with a deviating argument. Also, a numerical experiment is carried out and an example of calculating the deflection of the sensor’s moving element is presented.

Analysis of the Heating Process of Hydraulic Motors during Start-Up in Thermal Shock Conditions

Conditions that prevail during harsh winters and hot summers pose a serious challenge for machine designers building devices suitable for operation in extreme weather. It is essential for the designers and the users to define the principles and conditions for the safe operation of machines and devices with hydraulic drive in low ambient temperatures. Bearing in mind the above, the author tested the hydraulic motors in thermal shock conditions (cold motors were fed with a hot working medium). This enterprise required the design and construction of a specialized stand for testing hydraulic motors, including satellite motors, in thermal shock conditions. The stand was equipped with the apparatus and a system for measuring the temperature of the moving parts of the satellite motor. The experimental tests were conducted in the laboratory of the Faculty of Mechanical Engineering and Ship Technology at Gdańsk University of Technology. The paper presents the results of tests of a correctly and incorrectly operating satellite motor during start-up in thermal shock conditions. The results concerned the course of oil temperatures, temperatures of heated elements, oil pressures, and the pressure drop in the motor. The influence of the oil pressure drop in the motor on its temperature increase was determined. The distributions of the temperature fields of the heated elements of the satellite motor during start-up in thermal shock conditions were derived by means of computer simulation. The utilization of the distribution of the temperature fields of the motor elements enables the evaluation and analysis of the work of this unit. The conducted tests may determine the conditions for the proper operation of hydraulic motors started in thermal shock conditions.

The Main Ways to Control the Efficiency of Vibration Abrasive Processing

The paper considers the main factors affecting the stability of the technological operation of vibration abrasive processing. The main ways of increasing the efficiency of processing by controlling its stability are revealed. The scheme of adaptive control of the process of vi-broabrasive machining is proposed according to the criterion of stability of the volume of loading of the working chamber, as one of the main factors that determine the stability of the cutting ability of the working medium (tool). The work substantiates the relevance of increasing the efficiency of vibration processing, as one of the promising methods of finishing. As a criterion of efficiency, the processing time was taken to ensure the specified quality indicators of the processed parts. Taking into account the peculiarities of vibroabrasive processing, three options for determining the minimum required processing time are proposed. In order to identify ways to increase the efficiency of processing, the analysis of the structure of the technological system was carried out, the classification of its elements was made. Based on the results of the analysis, it was concluded that a necessary condition for increasing the efficiency of processing is to ensure the stability of the parameters of the technological operation. In this regard, the main factors influencing the stability of the technological operation of vibration abrasive processing using the Ishikawa diagram are highlighted. The paper also presents the results of experimental studies of the influence of the volume of loading the working chamber on the cutting ability of the tool (working environment). Based on the results of theoretical and experimental studies, the main ways of increasing the efficiency of processing, including by controlling its stability, have been determined. The scheme of adaptive control of the process of vibroabrasive processing according to the criterion of stability of the volume of loading of the working chamber, as one of the main factors determining the stability of the cutting ability of the working medium (tool), is proposed.

Application of the technology of induction chemical-thermal treatment to improve the physical and mechanical properties of tantalum

The results of the chemical thermal treatment (CTT) of tantalum in a solid carbon- containing medium in the temperature range from 1000 to 1300 °C were presented. CTT consisted in heating a workpiece with a working medium in a container made of a refractory material. The induction heating method was used for heating. After strengthening treatment, tantalum samples were characterized by increased hardness, which grew from 140 to 1100 HV0.02.

Algorithm of the dynamic functional of the adaptive torque distributor as applied to agricultural machines

The article deals with the problem of improving the drive of the driving wheels and working bodies of agricultural machines. The analysis of works on the research topic showed that this problem is solved by giving the very executive mechanisms of the agricultural machine the ability to adjust the characteristics in the direction that improves certain indicators of the quality of functioning, by the purpose of which it is possible to judge the efficiency of the operation of such a machine. The flexibility of the structure can only be ensured by the presence of additional degrees of mobility. Therefore, it is proposed to use differential mechanisms of varying complexity in the drive, which will provide continuous automatic regulation of its own operating parameters depending on changes in the resistance of the working medium to the executive bodies of the machine.