Given the state of the world nowadays, renewable energy is becoming more and more essential rendering wind turbine electricity quite important. Its shape and the fact that the Savonius vertical axis wind turbine runs at relatively low wind speeds with high torque values makes it suitable for practical uses such as that of an irrigation system in agriculture industry. This paper utilizes numerical research with Computational Fluid Dynamics (CFD) to investigate the performance of a vertical-axis wind turbine. The ANSYS CFD program was engaged to construct the simulations during the pre- and post-processing stages. Wind speed remained constant while the angular velocity was altered to enable analysis of the flow through the wind turbine. Because of its mechanical simplicity, the primary profile of a semicircle has remained a typical option for turbines that generate high torque based on drag force. The effects of using elliptical curves and the fluctuation in thickness along the profile chord were both examined in this study. Equivalently, an attempt to optimize the rotor's design was made. After the performance of a numerical simulation, a geometry consisting of simple circle arcs was developed, with a 10.9% improvement in the power coefficient, analogous to prior optimizations with more complicated geometries. The numerical results derived include the torque coefficient evolution throughout a full rotation as well as the distribution of vorticity magnitude at different rotor points.

In order to develop a sustainable economy based on the efficient use of green energy resources, it is necessary to research and innovate systems such as wind turbines. In this paper, a new configuration for vertical axis wind turbines was proposed and numerically analyzed using CFD methods. The concept is based on solving the starting problem of lift-based vertical axis wind turbines. The new concept consists of three blades with different chords, arranged at different radii so that the interaction between the blades is reduced and the operation in the vortex wake is minimal, thus reducing the losses. Through comparing a classic case of an H-Darrieus wind turbine with the new concept, not only were satisfying results regarding the blade-to-blade interaction presented, but an increased efficiency of up to 10% was also observed. Among the presented results is the variation of the vorticity magnitude at different positions of the blades, thus, the concept’s blade-to-blade interaction is reduced. Conclusions drawn after the investigation are in favor of the proposed geometry and the concept should be pursued further.

The popularity of small wind turbines intended for domestic use has significantly increased during the recent years, and it is reasonable to assume that this trend will continue given the present political and economic environment. There is a greater need for clean, pollution-free energy due to worries about climate change. In this study, a 1.5 KW vertical-axis Darrieus helix wind turbine for residential use was designed and its performance was mathematically evaluated under typical wind speed circumstances of 12 m/s. The study is split into two sections: In the first, we examined a standard wind turbine design with three identical blades, whereas in the second, the blades were different, each with a unique airfoil with a varying chord, even though they shared the same rotor diameter. For each case, 5 CFD simulations were performed in order to determine the power characteristics of the wind turbines. To correctly set up the computational domain, the number of elements and the minimum element size were taken into account whereas mesh dependency analysis was performed. In order to compare the results, the vorticity magnitude was measured at 4 different blade locations in each boundary condition. The results showed that when the power coefficient of the turbines is considered, such geometry adjustments are possible. Furthermore, the evolution of the torque coefficient over a full 360-degree rotation was studied. A summary of the improvements in performance resulting from the geometry adjustment is provided.

The oil and gas sector is important to the global economy because it covers the exploration, production, processing, transportation, and distribution of oil and natural gas resources. Despite constant innovation and development of technologies to improve efficiency, reduce environmental impact, and optimize operations in the gas and oil industry over the last few decades, there is still room to increase the efficiency of the industry’s equipment in order to reduce its carbon footprint. The separation of gas from oil is a critical stage in the technological production chain, and it is carried out using high-performance multi-phase separators to limit greenhouse gas emissions and have a low impact on the environment. In this study, an improved gas–oil separator configuration was established utilizing CFD techniques. Two separator geometry characteristics were studied. Both cases have the same number of subdomains, two porous media, and four fluid zones, but with a difference in the pitch of the cyclone from the inlet subdomain. The streamlines in a cross-plan of the separator and the distribution of the oil volume fraction from the intake to the outlet were two of the numerical results that were shown as numeric outcomes. The validation of these results was performed using an experimental testing campaign that had the purpose of determining the amount of lubricating oil that is discharged together with the compressed gas at the separator outlet.

For both conventional and renewable energy conversion processes, computational fluid dynamics (CFD) has been used to address more energy-related challenges in recent decades. Using CFD to investigate vertical-axis wind turbines has become more common in recent years. The main goals of this application have been to more accurately predict the turbine’s performance and to comprehend the complicated nature of the complex turbulent flow. The vertical-axis wind turbine (VAWT) simulation for energy-generating applications has several intricate components. One of them is the study of the chaotic flow that occurs during the first stages of the starting process, and which greatly influences overall effectiveness. In this article, the performance of the wind turbine was increased using a passive flow control approach. The numerical research was carried out using Large Eddy Simulation for four alternative tip speed ratios in both cases, the classic and the optimized case, equipped with a vortex trap on the extrados of the blades. The power and torque coefficient variations, as well as the velocity magnitude contours, show that the starting process may begin with a significant improvement in efficiency when flow control is used.

This paper presents an experimental investigation on using high strength-to-weight composite materials to reduce the mass of a centrifugal compressor impeller by 600%. By reducing the blades number from 17 to 7 and by doubling their thickness, the compression ratio and efficiency were maintained close to the reference metallic impeller. Using autoclave technology, seven composite blades were manufactured individually and assembled to form the impeller. After manufacturing, small deviations were found at the blade’s tip. As these deviations were found to be symmetrical, impeller balancing was successfully performed removing a total of 45 g of mass, followed by an experimental test on a dedicated test bench. Experimental testing identified the resonant frequencies of the composite centrifugal impeller at 13.43 Hz 805 rot/min and at 77 Hz with a 0.1 mm/s amplitude at 4400 rot/min, highlighting feasibility and the advantage of a composite compressor impeller design with application in centrifugal compressors and rotating machine assemblies and sub-assemblies. As there are numerous numerical investigations performed on the strength analysis and on the lay-up orientations mechanical behaviour for polymer composite materials with respect to the design of centrifugal impellers, no experimental evaluations in relevant working conditions have been performed to date. As the paper contains relevant experimental data on the subject, the outcome of the paper may aid the oil and gas or aviation industries.