CFD and experimental investigation of a diffuser-deflector assisted Persian VAWT for urban and industrial airflow energy harvesting

Numerical Analysis of Flow Conditions Inside an Impulse Turbine Under Reciprocating Flow

Oscillating water column wave energy converters require self-rectifying turbines capable of maintaining stable performance under bidirectional airflow. This study numerically investigates the aerodynamic performance and internal flow characteristics of an axial-flow impulse turbine using OpenFOAM under both uniform and reciprocating airflow conditions. Rotor motion was modeled using the Multiple Reference Frame approach, and the numerical model was validated against experimental data for one-way flow at an inlet velocity of 8.71 m s−1 and rotational speeds ranging from 300 to 1300 rpm. The CFD results successfully reproduced the experimental efficiency trend, yielding a peak efficiency of η = 0.4269 at 700 rpm and ϕ ≈ 0.95, which closely aligns with the experimental peak efficiency of η = 0.4425. Validation metrics demonstrated a high degree of accuracy, with an RMSE of 0.0219, a mean absolute error of 0.0197, a maximum absolute error of 0.0399, a squared Pearson correlation coefficient of 0.826, and a peak-efficiency difference of 3.5%. Flow-field analysis revealed that low rotational speeds resulted in high outlet velocities and incomplete energy extraction, whereas excessive rotational speeds caused flow misalignment, downstream vortex formation, and additional aerodynamic losses. Under reciprocating flow conditions, characterized by a sinusoidal velocity amplitude of 8.71 m s−1 and periods of 0.5–2.0 s at 700 rpm, both input and torque coefficients exhibited hysteresis, with the strongest loops observed at the shortest periods. Examinations of streamline, pressure, and velocity distributions indicated that residual flow during flow reversal alters the effective inlet direction in the subsequent half-cycle, resulting in flow memory and a phase-dependent turbine response. As the present computational domain excludes the OWC chamber, these findings characterize turbine-level aerodynamic performance rather than the complete system power coefficient.

Design and Construction of a Savonius Helix-Type Vertical Axis Wind Turbine Using Computational Fluid Dynamics

This study presents the design, simulation, fabrication, and experimental validation of a Savonius Helix vertical axis wind turbine optimized for low wind regimes in Cilacap, Indonesia. Wind data from NASA POWER were analyzed at two locations, revealing dominant low wind conditions with notable temporal variability. The turbine geometry was optimized based on aerodynamic and inertial parameters, followed by Computational Fluid Dynamics (CFD) simulations to evaluate torque, pressure distribution, and power coefficient across four configurations (2B90P, 2B180P, 3B90P, 3B180P). The optimal design was fabricated using fiberglass and tested under no-load and loaded conditions with a Permanent Magnet DC generator. Results indicate strong agreement between CFD trends and experimental performance, despite deviations caused by mechanical losses and atmospheric turbulence. Overall, the Savonius Helix configuration demonstrates effective energy capture capability in low wind environments, confirming its feasibility for small-scale renewable energy applications.

CFD-Based Numerical Analysis of a Vertical Axis Wind Turbine

This research is a numerical investigation into the two-dimensional configuration of a Savonius vertical axis wind turbine (VAWT) using computational fluid dynamics (CFD). Transient analysis has been performed on this turbine using rotatable domains in COMSOL Multiphysics to capture the unsteady aerodynamic characteristics. A transient analysis was also performed using the incompressible Navier-Stokes equations to determine the following performance characteristics: velocity distribution; pressure distribution; torque generated by turbine; and acceleration of rotor. The results showcase how blade flow asymmetry between advancing and returning blades creates periodic vortex shedding patterns, and how the torque generated is also fluctuating. For the purpose of this analysis, the torque increases from near zero torque to approximately 0.45 N·m., while the angular velocity grows from 0 rad/sec (initially) to roughly 37 rad/sec (maximum velocity achieved) during the transient analysis. During the simulation, the rotor speed achieved during transient analysis is approximately 350 rpm, with a corresponding mechanical power value ranging from approximately 16 to 17 W. The results obtained from the transient analysis suggest that the flow separation and wake behaviour associated with unsteady states are critical to determining the overall turbine performance. Furthermore, the CFD model created through this investigation establishes a solid methodology for determining the performance of Savonius vertical axis wind turbines relative to predicted aerodynamic characteristics and design optimization criteria.

Experimental and CFD analysis of Horizontal Axis Wind Turbine with Umbrella scoop attachment

CFD-Based Aerodynamic Optimization of Vehicle-Mounted Axial Wind Turbine Blades

The increasing demand for sustainable energy solutions has encouraged the development of renewable energy technologies that can be integrated into various applications, including transportation systems. Wind energy generated from vehicle-induced airflow represents an alternative energy source that remains underutilized due to complex aerodynamic characteristics and unstable flow conditions. This study aimed to optimize the aerodynamic performance of vehicle-mounted axial wind turbine blades by determining the most suitable angle of attack using Computational Fluid Dynamics (CFD) simulations. The research method involved numerical analysis using CFD software to evaluate the aerodynamic behavior of turbine blades under different angle-of-attack variations of 0°, 5°, 10°, 15°, and 20°. Performance evaluation was conducted based on the lift-to-drag ratio and velocity contour distribution to identify the optimal blade configuration. The results showed that the angle of attack significantly affected aerodynamic performance, with the 10° configuration producing the highest lift-to-drag ratio and the most favorable airflow characteristics. Higher angles of attack resulted in increased flow separation and aerodynamic losses, whereas lower angles produced insufficient lift generation. The optimized turbine design consisted of six blades with a rotor diameter of 0.35 m, demonstrating the potential application of vehicle-induced airflow energy harvesting systems. In conclusion, CFD-based optimization provided an effective approach for improving the performance of vehicle-mounted wind turbine blades and supported future development of renewable energy technologies for sustainable transportation applications.

Electromechanical and CFD-coupled analysis of deflector-guided savonius pico-hydro turbine with quarter-circular blade rotors

Global electricity demand continues to rise, increasing dependence on fossil fuels and accelerating greenhouse gas emissions that contribute to climate instability. Small-scale hydropower offers a clean alternative, particularly for distributed and space-constrained applications where conventional hydropower systems are difficult to implement. Among available concepts, the Savonius Pico-Hydro Turbine (SPHT) is attractive because of its simple structure, low production cost, and good self-starting capability. However, previous studies have mainly focused on mechanical performance, while the combined evaluation of mechanical response, electrical output, generator efficiency, and hydrodynamic flow behavior remains limited. The novelty of this study lies in the use of a quarter-circular blade profile instead of the commonly used semi-circular Savonius blade, combined with experimental electromechanical testing, CFD-based flow visualization, and deflector-angle variation. Two- and four-blade SPHT configurations were examined under realistic loading conditions, while CFD simulation was employed to clarify velocity distribution, pressure loading, momentum exchange, and deflector-guided flow patterns. The results showed that the four-blade rotor produced higher torque and a stronger electrical response than the two-blade rotor. CFD contour analysis supported these findings by showing stronger momentum exchange and more distributed pressure loading around the higher-solidity rotor. The deflector investigation further indicated that a 30° deflector angle provided the most effective flow redirection and pressure distribution among the evaluated cases. Overall, the proposed experimental and numerical framework provides a practical basis for optimizing quarter-circular SPHT design through blade configuration selection and deflector-angle tuning, supporting compact and reliable pico-scale clean energy generation for remote and low-infrastructure applications.