Experimental Investigation of Possibilities to Improve Filtration Efficiency of Tangential Inlet Return Cyclones by Modification of Their Design

Experimental Studies of Welded Joints in Structures Subject to High Impact Vibrations Using Destructive and Non-Destructive Methods

This article presents the issues of control and quality assurance of high-strength railway rail joints. Selected test results and requirements for rail joints made by welding with stationary welders on the basis of the requirements included in the PN-EN standards have been described. In addition, destructive and non-destructive tests of weld quality were performed, including visual tests, geometrical measurements of irregularities, magnetic particle and penetration tests, fracture tests, observations of micro- and macro-structure and hardness measurements. The scope of these studies included conducting tests, monitoring the process and evaluating the results obtained. Laboratory tests on the rail joints confirmed the good quality of the rail joints from the welding shop. Increasingly less damage to the track in places of new welded joints is proof that the methodology of laboratory qualification tests is correct and fulfils its task. The presented research will help educate engineers on the welding mechanism and the importance of quality control of rail joints during their design. The results of this study are of key importance for public safety and will improve knowledge on the correct implementation of the rail joint and how to conduct quality control tests in accordance with the requirements of the currently applicable standards. It will help engineers choose the right welding technique and choose solutions to minimize cracks.

Simulation Study on the Corrugated Plate Gas-Liquid Separator with the Assistance of the Drainage Hook

Corrugated plate separators are widely used in the field of gas-liquid separation because of their excellent separation performance. The separation effect is very sensitive to the internal auxiliary structure of drainage hooks, so it is extremely important to study the action principle of drainage hooks to optimize the performance of corrugated plate separators. In this paper, Fluent is used as the solver and the realizable k-ε model is used to compare the separation performance of unhooked, single-hooked, and double-hooked corrugated plates. The results show that the separation efficiency of wave plates with hooks can reach 100%, the separation efficiency of wave plates without hooks is about 90%, and the superiority of the separation efficiency of single-hook and double-hook wave plates is related to the droplet partition diameter, which is positively correlated with Re. The pressure drop and separation efficiency increase with the increase of plate hook spacing, and the pressure drop and separation efficiency of single-hook and double-hook corrugated plates have different performance advantage zones influenced by Re and K _a. When the Re is 9.64 × 10³ and K _a is 0.294, the separation effect of corrugated plates with the single hook and double hook is the same. Through the analysis of the gas-phase flow field and droplet motion trajectory, it is found that the drainage hook enhances the separation effect of the corrugated plate separator by increasing the local gas velocity and forming a vortex inside the drainage hook.

Experimental Studies of PowerCore Filters and Pleated Filter Baffles

The material most commonly used to filter and clean the intake air of vehicle internal combustion engines is pleated filter paper, which in most cases is shaped in the form of a cylinder or panel. The production technology has a low cost and is not complicated. In addition to high separation efficiency and filtration performance, pleated filter media are required to have low initial pressure drop, which depends on the geometry of the bed. Much research has been conducted in this area. Dust accumulated in the filter bed causes an increase in pressure drop, which is the cause of deformation and sticking of pleats. The lack of stability of the pleats, the need to strengthen them, and the need to obtain small sizes while achieving high efficiency and accuracy of filtration of engine intake air was the reason for the development of a different design and a new technology for making filter cartridges called PowerCore. The distinctive feature of these filters is axial flow in one direction of the air stream, which avoids turbulence and thus minimizes pressure drop. This paper presents a comparative analysis of a standard PowerCore and PowerCore G2 filter bed and two cylindrical filters with a pleated filter bed made of cellulose and polyester. The conditions and methodology of experimental testing of filters with test dust are presented. During the tests, the characteristics of separation efficiency and filtration performance, as well as pressure drop as a function of the mass of dust retained on the filter of two PowerCore filters and two cylindrical filters were performed. Three specimens of test filters with the same filtration area were made from each sample of filter bed. The results showed that in each test of the filter bed, there is an initial filtration period characterized by low (96-98%) initial separation efficiency and the presence of large (d_pmax) dust grains. As the dust loading of the bed increases, the separation efficiency and filtration performance obtain higher and higher values. The initial period of filtration ends when the conventional value (99.9%) of separation efficiency is reached. The duration of this period depends on the type of filter bed and for the PowerCore G2 filter ends for a dust loading of k_m = 33.1 g/m², and for the cellulose filter for k_m = 117.3 g/m². During the initial period, the air behind the PowerCore G2 filter contains grains with sizes in the range of d_pmax = 9-16 µm. Behind the cellulose filter, dust grains are much larger, d_pmax = 17-35 µm. The total operating time of the PowerCore G2 filter, limited by the achievement of the permittivity resistance Δp_wdop = 3 kPa, is twice that of the other filter compositions tested.