The article is focused on the comprehensive analysis of the aerodynamics of air distribution devices with the combined heat and mass exchange, with the aim to improve the following hydro- and thermodynamic parameters of ventilation systems: flow rate, air velocity, hydraulic losses, and temperature. The inadequacy of the previously obtained characteristics has confirmed the need for more rational designs of air distribution systems. Consequently, the use of perforated plates was proposed to increase hydraulic losses for reducing the average velocity and ensuring a uniform distribution of the velocity field on the outlet of the device. The effectiveness of one of the five possible designs usage is confirmed by the results of numerical simulation. The coefficient of hydraulic losses decreased by 2.5–3.0 times, as well as the uniformity of the outlet velocity field for the air flow being provided. Based on the three-factor factorial experiment, the linear mathematical model was obtained for determining the dependence of the average velocity on the flow rate, plate’s area, and diameter of holes. This model was significantly improved using the multiparameter quasi-linear regression analysis. As a result, the nonlinear mathematical models were obtained, allowing the analytical determination of the hydraulic losses and average velocity of the air flow. Additionally, the dependencies for determining the relative error of measuring the average velocity were obtained.

The difficult operating conditions during the pumping of abrasive solid mediums lead to the rapid wear of the mechanical parts of the pumps. The use of jet pumps can significantly increase the reliability and durability of pumping equipment. However, direct-flow jet pumps have low efficiency. The use of the centrifugal force led to the creation of new jet pumps - vortex chamber pumps. Their performance indicators are better than direct-flow jet pump ones. The geometric parameters of the flow channel of the vortex chamber pumps were optimized. The study was carried out experimentally and numerically. Numerical simulation is based on solving the RANS equations with the shear stress transport turbulence model. The geometrical dimensions of the vortex chamber pump with the best performance indicators such as pressure and flow are found. The maximum achievable operating parameters of the vortex chamber pump are analyzed. The comparison of simulation results with experimental data is made.

На прикладi тестової задачi дослiджуються особливостi впливу рiзних чинникiв на напружено-деформований стан складених тонкостiнних конструкцiй iз болтовим з'єднанням окремих елементiв. Прикладом таких конструкцiй є металiчнi зерносховища -силоси, якi складаються iз панелей, що з'єднуються болтами. Тестова конструкцiя мiстить двi вузьких плоских смуги, з'єднаних внакид. У отвори в цих смугах розмiщений болт iз попереднiм затягуванням. Ураховується тертя i проковзування смуг i болта, контакт бiчної поверхнi болта i отворiв, а також взаємний вплив вигину i розтягування. Таким чином, у моделi врахованi геометрична, фiзична i структурна нелiнiйностi. Система пiддається дiї поперечного навантаження, яке прикладене до однiєї сторони смуги. Моделюється поетапне навантаження систем. Встановлено, що при навантаженнi дослiджувана система набуває прогин, який нерiвномiрно зростає з ростом навантаження. Це зумовлено тим, що на нього впливає i пружна деформацiя смуг, i взаємне проковзування в зонi з'єднання. При остаточному вибираннi зазору мiж болтом i отворами в панелях вiдбувається переважно пружне деформування системи. Пiсля першого розвантаження в системi установлюється залишковий прогин. Також встановлено, що у системi дiють поздовжнi зусилля, якi можуть бути набагато бiльшими вiд поперечних сил вiд навантаження. Характерним є сильний взаємний вплив вигину i розтягування смуги. У результатi дослiджень встановлено чинники, що визначають напружено-деформований стан дослiдженої системи: геометрична нелiнiйнiсть, контактна взаємодiя, тертя i проковзування, зв'язанiсть вигину i розтягування. Таким чином, без урахування всiх цих чинникiв розрахункова модель для подiбних тонкостiнних конструкцiй буде неадекватною, результати розрахункiв iз її застосуванням матимуть значнi похибки, а рекомендацiї -недостовiрними. Здiйсненi дослiдження дають можливiсть розроблення бiльш адекватних моделей для аналiзу реакцiї складених тонкостiнних конструкцiй на дiю навантаженняКлючовi слова: тонкостiнна конструкцiя, болтове з'єднання, напружено-деформований стан, металiчне зерносховище, геометрична нелiнiйнiсть UDC 539.3

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The labyrinth screw pumps are widespread in the chemical and oil industries. The scope of the possible use of the labyrinth-screw pumps working in aggressive mediums is much wider in comparison with the pumps with similar pressure and flow parameters. This is due to the type of operation and lack of the mechanical friction of the parts. Increasing the pump flow rate can be achieved by reducing hydraulic friction resistance or profiling the inlet and outlet of the fluid flow. The flow channel of the labyrinth screw pump has been improved and a new design of its movable operating elements has been developed based on the proposed concept of jet resistor diodes. The reduction of hydraulic resistance in the flow channel of the pump with the working fluid flow in the forward direction and increasing the resistance of the diode made it possible to obtain a more efficient design. The results of improvement are compared with experimental data. The simulation of the flow in the pump is performed by solving the RANS equations with the SST turbulence model. The flow predictions in the flow section are obtained. The flow rate characteristics of typical and developed pumps are calculated. The developed pump design allows for increasing its flow rate by almost 10%. At the same time as the flow rate of the pump increases its power output. The efficiency of the industry-developed labyrinth screw pump application is proven by comparing the flow rate characteristics of the pumps.

To date, the assessment of the technical level of individual elements of hydraulic drive systems has been significantly addressed, but most of them were positive-displacement machines. Thus, the development of a criterion which takes into account the maximum number of indicators and hydraulic devices and is based on common methodological principles is an important scientific and technical task for the assessment of the technical level of hydraulic machines, hydraulic units, and hydraulic devices. Based on a systematic analysis of the technical level evaluation indicators of a wide range of hydraulic drive system elements, namely hydraulic machines, hydraulic units, and hydraulic devices, a definitive criterion for assessing their technical level is synthesized. There were two stages in the study: theoretical and experimental. Initially, the most important factors influencing the reliability and efficiency of hydraulic devices were defined on the basis of operations research methods (hierarchy analysis method and multicriteria optimization). After the synthesis of the criterion, an experimental test was carried out based on a comparison of maintenance costs of real hydraulic devices. The obtained criterion allows one to make an assessment depending on constructive and operational indicators, based on common methodological principles. A comparison of the characteristics of maintenance costs of hydraulic devices per unit of power was made. Characteristic curves are hyperbolic, which proves the validity of the criterion.

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