Експериментальне дослідження рідинно-парового ежектора з конічною камерою змішування

The article is devoted the design of working process of liquid-vapor ejector of a vacuum unit with conical mixing chamber, working on principle of stream thermocompression, research of influence of thermodynamic parameters and descriptions of active and passive streams on the process of mixing with the purpose of achievement of most vacuum unit efficiency.The main content of the article is study the nature of passive mixing flows with different thermodynamic properties on the geometric parameters of the mixing chamber.Experimental study of liquid-vapor ejector with conical mixing chamber on a transparent model allowed to confirm the mechanism of the working process at pressures below atmospheric pressure, namely the boiling of metastable superheated liquid, characterized by the presence of three critical sections expiry of expanding the channels to the definition section of flow separation from the walls of the channel and its position relative to the nozzle exit of active flow. Also the nature of the mixing process in the chambers of conical shape is investigated. It allows establishing maximum efficiency by optimizing the flow of liquid-vapor ejector with conical mixing chamber.The estimation of the appropriateness of units on the basis of LVE in vacuum systems through a comparative exergy analysis of basic and alternative schemes offered by the method of J. Tsatsaronis.В статье приведена модель расчета геометрических и энергетических параметров конической камеры смешения жидкостно-парового эжектора. Представлены результаты экспериментального исследования плоскопараллельного жидкостно-парового эжектора с камерой смешения конической формы и проведен их сравнительный анализ с теоретическими данными. Выполнен анализ эксергетической эффективности применения эжектора с конической камерой смешения.У статті подана модель розрахунку геометричних та енергетичних параметрів конічної камери змішування рідинно-парового ежектора. Представлені результати експериментального дослідження плоскопаралельного рідинно-парового ежектора з камерою змішування конічної форми і проведено їх порівняльний аналіз з теоретичними даними. Виконано аналіз ексергетичної ефективності використання ежектора з конічною камерою змішування

Influence of typological features of the nervous system on individual performance in running for short distances in athletes with visual impairment on the example of an elite athlete

Introduction: The purpose of the work is to theoretically and experimentally substantiate the influence of psychophysiological factors on individual performance in athletics sprint in high-qualified athletes on the example of an elite athlete. Material and methods: In this study, participated 1 athlete, 36 years of age, female. Athlete is specializing in short-distance running and long jump, the European Athletics Champion 2010; prize winner of the World Paralympic and Paralympic Games among athletes with visual impairments (T12 category) in 2016. The study was conducted for 5 months. Twice a week, testing was conducted (psychophysiological indicators and running speed); 36 tests of one athlete were conducted. Individual characteristics of the psychophysiological state and results in running for 100 m for five months were analyzed. Results. The models of multiple linear regression between results in 100 m run for an elite athlete with visual impairment and psychophysiological indices are compiled. High importance of psychophysiological indices in individual performance in running on 100 m is shown. Conclusions. Compensatory mechanisms of visual function deficiency were established to maintain high speed in the 100 m run as psychophysiological functions: indicators characteristic of sprinters (speed of simple reaction and motility of the nervous system) and specific indicators (efficiency, strength of the nervous system)

Comparative biomechanical characteristics of one-arm hang in climbing for beginners and qualified athletes

The aim of the study was to identify the basic kinematic characteristics of the one-arm hang in climbing for beginners and qualified climbers. Material and methods: Technique of the one-arm hang in climbing among 20 leading climbers of the World and Ukraine and 20 beginner male amateur climbers was analyzed. A qualified athlete participated in the demonstration of various models of the one-arm hang performance. By means of Kinovea software 0.8.15, the kinematic characteristics of two models of the technique were analyzed (model 1 for beginner athletes, model 2 for qualified athletes). Results: The presence of significant differences ( p < 0.001) between beginners and qualified athletes in the magnitude of the angles between the shoulder and clavicle, between the spine and the vertical axis in the phase of fixation of the one-arm hang was revealed. The dynamics of the angle between the shoulder and clavicle from the moment of capture of the climbing hold to the phase of fixation of the hang was shown. A theoretical justification for the correct climbing technique regarding to the laws of mechanics and the laws of force interaction in kinematic chain was provided. Conclusions: Beginner athletes carry out the one-arm hang mainly due to the ligamentous apparatus of the joints of the shoulder girdle with minimal inclusion of muscles, which is dangerous by trauma to the ligaments of the shoulder joint. Skilled athletes perform the one-arm hang with trunk and leg muscles included, which reduces the strain from the ligamentous apparatus and lowers the possibility of injury to the ligaments of the shoulder joint