Purpose: Rotating machines play a strategic role in the process; it is the case of a gear unit of a cement mill. These machines are composed of tribo-pairs (bearings and gears, etc.) subjected to mechanical stress and harsh industrial environments. This study aims to make an experimental investigation of bearing wear of a gear unit DMGH 25.4 of a horizontal cement mill. Design/methodology/approach: Several tests were carried out in collaboration with industrial Algerian companies, for example, spectroscopy, micro hardness, X-Ray diffraction analysis and microscopic examination of wear-characterized QJ1244 N2MA bearing. Findings: Experimental results reveal that there are two types of bearing wear: the first is a continuous mode of damage. The second mode is the wear by a third body (wear debris in suspension in oil). The spalling results from the propagation of cracks through the thickness of the material generally give rise to cracks in the sub-layer depth hertz. An unusual hardening observed suggests that the damage was caused by the dissipation of a large surge of frictional energy lasting several milliseconds. It is found also that heating due to insufficient lubrication of the bearing led to the formation of high-density fine carbides in the microstructure of 100Cr6, which tends to decelerate the movement of dislocations during plastic deformation. Practical implications: This study allowed the characterization of bearings wear in industrial mechanical systems. Originality/value: Characterization of the bearings showed that the unusual hardening observed suggests that the damage was caused by the dissipation of a large surge of frictional energy lasting several milliseconds. The microhardness of the worn bearing is very high compared to the beginning wear bearing, which is due to the quantity of carbides formed. The thermo-mechanical stresses do not affect the main phases such as martensite, but they accelerate the fracture propagation at the surface.

In this article, we present an investigative study on the often-overlooked partial wake phenomenon in previous studies concerning wind farm configurations. A partial wake occurs when a portion of the actuator disk of a downstream wind turbine is affected by the wake of another upstream turbine. This phenomenon occurs in addition to the full wake, where the entire upstream turbine is affected by the wake of the frontal turbine, also leading to a decrease in wind speed and consequently a reduction in power production. The proposed study is based on measuring the power generated by the area swept by the wake of an array of turbines in a wind farm. To accomplish this, we integrate the linear wake model of Jensen, the specifications of the ENERCON E2 wind turbine, and the wind farm data into Matlab-developed software (version 18) to perform the calculations. In a concrete application, this proposed method is validated by reproducing the previous works that neglected the partial wake in wind farm configurations. The simulation results obtained are analyzed, compared, and discussed under similar operational conditions.

With the world’s growing demand for energy, renewable energy production has become important in providing alternative sources of energy and in reducing the greenhouse effect. This study investigates the aerodynamics and performance of the WG/EV100 micro–Horizontal Axis Wind Turbine (HAWT) using Computational Fluid Dynamics (CFD). The complexity of VAWT aerodynamics, which is inherently unsteady and three-dimensional, makes high-fidelity flow models extremely demanding in terms of computational cost, limiting the analysis to mainly 2D Computational Fluid-Dynamics (CFD) approaches. This article explains how to perform a full 3D unsteady CFD simulation of HAWT. All main parts of the WG/EV100 HAWT were designed in SOLIDWORKS. Only the blade design was reverse engineered due to the unavailability of the CAD model and the complexity of its geometric characteristics. The impeller blade is scanned using a Coordi-nate Measuring Machine (CMM), and the obtained 3D scan data are exported from the PC-DMIS software to GEOMAGIC design X to obtain a CAD model of the blade.

Inconel738 is a nickel-based super alloy widely used in manufacturing gas turbines, particularly in the manufacture of blades that are in direct contact with hot gases during their operation. As a result, these blades are subjected to high temperatures, significant static and dynamic stresses, erosion and/or hot corrosion which can be very severe. The use of coatings is one of the most effective strategies to protect materials against corrosion and increase the wear resistance of materials. In this study, β-Ni-Al coatings were sprayed onto an Inconel738 substrate using a wire flame spraying process and characterization of coating has been made.

During the operation of a rotor, various types of vibrations appear in this mechanical system and often limit the performance and endanger the safety of the operation. Therefore, dynamic analysis is essential because precise knowledge of the vibration behaviour is essential to ensure proper operation. This article presents a set of scientific techniques for the modelling and simulation of rotor vibrations. To work out the equations of the vibratory movement of the rotor, we used the energy approach of Lagrange. To achieve this, a model with one blading wheel carried by a shaft supported by two hydrodynamic bearings is chosen basedon the characteristics of the rotor studied (Fan 280 cement draft fan). It is an arduous task to manually ascertain the analytical resolution of the differential equations that characterise the vibratory behaviour of the rotor. The numerical approach employing the finite element method, programmed on the ANSYS software, made it possible to perform the vibration analysis of the rotor. First, the FAN 280 cement draft fan rotor is modelled using SolidWorks 3D software and reverse design using the coordinate measuring machine (CMM) for the design of the fins. Then, the modal characteristics of the fan rotor model were analysed using the finite element analysis (FEA) software ANSYS Workbench. Also, to study the effect of blade wear on critical speeds, the Campbell diagram was obtained. Finally, harmonic analysis was performed to determine the amplitude of the rotor vortex at critical speeds obtained with and without blade wear.

In many engineering applications, particle-laden flows are a necessary part of the conveying process, but in other situations, they could have unintended consequences that must be avoided. As a part of the exhausting process, the induced cement-mill fan (FN-280) installed in a cement plant operates under critical conditions with the presence of high content of cement particles. Over time the dragged solid particles erode the rotating and stationary parts of the fan causing their damage. If one decides on a numerical approach to predict regions most prone to erosion and track the solid particle's trajectory within the fan domain by assuming a one-way coupling regime between the continuous and discrete solid phases, a deep insight into the flows physics within the centrifugal fan is required. With this aim, a three-dimensional numerical approach for the hole unsteady flow in a large-sized industrial centrifugal fan has been carried out in this paper. A fully resolved sliding mesh approach was employed to take into account the unsteady interaction between the impeller and the discharge volute. Based on the characteristic performance curves, the numerical results of the unsteady simulation at four operating conditions are validated with the experimental data. The comparisons reveal that the results of the unsteady simulation are in an acceptable level of agreement with the experiment, demonstrating the validity of the modelling approach adopted in this study.