Center-Oriented Aiming Strategy for Heliostat with Spinning-Elevation Tracking Method

Spinning-Elevation (SE) tracking system produces a decent image on the receiver surface; however, it is subjected to large variations in tracking speed. In this research, a Graphical Ray Tracing (GRT) model for Center-Oriented Spinning-Elevation (COSE) tracking method is developed to evaluate tracking angles. Instead of a target, a heliostat is pointed towards the on-field center point of the tower. Therefore, a spinning-axis of rotation is a line joining a heliostat, and a center of the tower and elevation-axis is perpendicular to it. This aiming strategy has shown a substantial reduction in rotations of spinning-motor. In contrast, the elevation-motor runs at slightly higher rotations than the target-oriented SE method for the same application. Also, COSE tracking method obtains better shape of the reflected image with less aberration on the receiver surface as compared to SE and the traditional Azimuth-Elevation (AE) method.

Influence of Fluid Compressibility and Movements of the Swash Plate Axis of Rotation on the Volumetric Efficiency of Axial Piston Pumps

This paper describes the design of a swash plate axial piston pump and the theoretical models describing the bulk modulus of aerated and non-aerated fluids. The dead space volume is defined and the influence of this volume and the fluid compressibility on the volumetric efficiency of the pump is considered. A displacement of the swash plate rotation axis is proposed to reduce the dead space volume for small swash plate swing angles. A prototype design of a pump with a displaced axis of rotation of a swash plate with two directions of delivery is presented, in which the capacity is changed by means of a valve follow-up mechanism. Comparative results for a pump with a displaced and a non-displaced swash plate rotation axis are presented, which confirm that displacement of the swash plate rotation axis causes an increase in volumetric efficiency that is apparent for high pressure discharge and small swash plate angles. The determined characteristics were compared with a mathematical model taking into account the compressibility of the fluid in the dead space volume and a satisfactory consistency was obtained.

STATE OF THE ART OF SMALL WIND ENERGY ANALYSING DIFFERENT CONTROLS

There are two wind turbine topologies according to the axis of rotation: horizontal axis, "Horizontal Axis Wind Turbines" (HAWT) and vertical axis, "Vertical Axis Wind Turbines" (VAWT) [2]. HAWT turbines are used for high power generation as they have a higher energy conversion efficiency [2]. However, VAWTs are used in mini wind applications because they do not need to be oriented to the prevailing wind and have lower installation cost.

PROBLEMS OF DRIVE MECHANISMS OF TECHNOLOGICAL SECTION OF FIRING AND GRINDING DURING CEMENT PRODUCTION

The analysis of conditions of long operation of driving mechanisms of technological sites of firing and grinding at cement production is carried out in the work. Typical variants of mutual arrangement of crown pair elements in case of rectilinear axis of rotation of technological unit body and axial beating of gear ring, as well as variant of mutual arrangement of crown gear elements in case of curved axis of rotation of rotary unit body are considered. A technique for determining the total angle of skew of the teeth of the crown pair, taking into account the errors of manufacture and the relative position of the wheels of the open gear. On the basis of experimental data the dependences of the total skew angle of the teeth of the crown pair as a function of the rotation angle of the gear crown are constructed and the possible range of the total skew angle under different operating conditions of the considered large rotating units is determined. To assess the stress-strain state of the elements of the ring gear mounted on the furnace body, a solid model was created in the software environment Solid Works Simulation. As an example, the dependences of the change in the magnitude of the deformation of the teeth of the toothed crown in the plane of action of a uniformly distributed normal force are determined. Practical recommendations for improving the design of the crown gear pair are offered. Keywords: rotary kilns; mills; crown gear; toothed crown; the angle of skew of the teeth; finite element method

Analysis of the umbrella-type reflector opening process on a stand with an active gravity compensation system

During the verification of the functioning of the transformed structures in ground conditions, it is necessary to minimize the effect of gravity in order to exclude the occurrence of additional loads on the hinge assemblies and opening mechanisms. To perform this task, when testing a transformable umbrella-type reflector, stands with an active gravity compensation system are used, in which the gravity compensation force is applied to each spoke of the reflector. However, when compensating for the gravity spokes of the reflector, the fixing point of the suspension cable does not coincide with the center of mass of the spoke, which leads to the appearance of additional moments of forces acting on the suspended structure. Therefore, as an object of research, a part of the reflector was considered, consisting of a spoke, with cords of a formforming structure attached to it and a mesh. A 3D model has been developed, using which the positions of the center of mass of the structure under consideration were determined in the key phases of the reflector opening. A computational analysis of the driving forces and moments acting on the structure in the process of disclosure is carried out. The degree of influence of the suspension point position on the inaccuracy of gravity compensation has been established. The results of the analysis presented in the article can be used as initial data for the development of an algorithm for the operation of an active gravity compensation system, which will be able to take into account the position of the suspension point and the center of mass of the structure relative to the axis of rotation of the spoke during the opening of the reflector, by changing the gravity compensation force.

Dynamic analysis of a ten-link tooth-lever differential transmission

This article discusses the dynamics of a ten-link tooth-lever differential transmission mechanism. The force analysis of the transmission mechanism is given in order to find the dependence for determining the reaction in kinematic pairs and the balancing moment of the pair of forces and to show some features of the tooth-lever transmission mechanism. The force calculation was carried out taking into account the accelerated movement of links since their acceleration in modern high-speed machines is very significant. To obtain a more accurate concept of the external forces and moments loading the transmission mechanism in the accelerated movement of the links, the dynamics of the transient process of roller technological machines was considered. Cases of feeding the processed material were considered both from the side of the intermediate gears and from the side opposite to the parasitic gears. Dependencies were obtained to determine the force characteristics of this mechanism. Cases of pressure unloading and overloading on the processed material from the side of the free shaft, depending on the location of the transmission mechanism are shown. The dependence of the reaction force of intermediate gears on their own axes of rotation on the angle between the levers is shown. With an increase in the angle between the levers, the reaction of the intermediate gears on the axis of rotation increases.

Improving the efficiency of carousel wind turbine using aerodynamic shield

The problem of increasing the efficiency of using the oncoming air flow for a wind wheel with a vertical axis of rotation, which is a mechanical drive of the wind heat generator, is considered. It is proposed to increase the efficiency of the device by installing an aerodynamic shield for the air flow oncoming the wind wheel. Such a shield is a cylindrical body in which a heat generator is placed. The shield creates an effect of confuser, leading to an increase in the speed and, consequently, in the kinetic energy of the air flow acting on the rotor blades. It is shown experimentally that the presence of an aerodynamic shield under the conditions of the experiments carried out at an incoming air flow velocity of ~ 1 m/s leads to a practical doubling of the wind wheel torque.

Study on combined machine for the subsurface soil treatment

The purpose of the study is to substantiate the relative position of the working bodies of a combined machine for non-fall tillage of winter crops. The design scheme and the principle of operation of the combined machine are given. The basic principles and methods of classical mechanics, mathematical analysis and statistics were used in this study. It is established that the most optimal design scheme of a combined machine for non-tillage of the soil and its preparation for sowing of repeated crops is considered to be a scheme consisting of non-tillage cases with crushers, a battery with cut-out spherical disks and a roller. According to the results of theoretical and experimental studies, it was found that with a longitudinal distance between the shaft-free bodies of 40 cm and a transverse distance of 90 cm, a longitudinal distance from the toe of the ploughshare to the center of the support wheel of 50 cm and a longitudinal distance from the toe of the ploughshare of the shaft-free body to the axis of rotation of the cut-out spherical disk of 120 cm, a longitudinal distance from the axis of rotation of the cut-out spherical disk to the center of the roller of 75 cm, high-quality tillage with minimal energy costs is provided.

Effect of the forces of one-way magnetic attraction on the reliability of the bearing unit of the traction switched reluctance motor

The subject of the research is a traction switched reluctance motor with an uneven air gap. The main purpose of the work is to determine the forces of one-way magnetic attraction, evaluate and analyze these forces, develop measures to reduce the forces to an acceptable value. In the article, the forces of disbalancement and the forces of one-way magnetic attraction are considered in the relationship. The finite element method was used to determine the main parameters of the switched reluctance motor. The studies were carried out for two idealized variants of the location of the rotor rotation axis. In the first case, the axis of rotation is combined with the axis of symmetry of the stator. The second option considers the case of displacement of the axis of rotation together with the axis of symmetry of the rotor. It is determined that the resulting force of one-way magnetic attraction with an uneven air gap reaches significant values and significantly exceeds the permissible values. An algorithm for calculating the characteristics of a switched reluctance motor is proposed, which takes into account the tolerances for the manufacture of its design elements. The algorithm allows you to adjust the requirements for the bearings used, ensure the required level of reliability of the traction switched reluctance motor (SRM) and predict the level of vibration and noise.