Wind Turbine Blade Dynamics Simulation under the Effect of Atmospheric Turbulence

Wind energy is one of the fastest growing sources of renewable energy because of its cleanliness and sustainability. Due to the turbulent nature of wind, a wind turbine experiences severe dynamic loading and faces the danger of fatigue failure. In addition, severe blade deflections imply failure by tower strikes. For this reason, the study of blade deflections under different turbulence conditions is of high importance. In this work, a wind turbine’s blade is simulated under different turbulent conditions. Four different wind fields are generated with a mean wind velocity of 12 m/s and turbulence intensities of 1, 10, 25, and 50%. The blade deflections are calculated in the out-of-plane and in-plane directions as a time-marching series with different blade azimuth positions. The higher the turbulence intensity, the severer the fluctuations of the deflections around its mean value. For the 50% turbulence intensity, the standard deviation of the out-of-plane deflection is 600% larger than that of the 1% turbulence intensity case. The maximum deflections increase significantly as well. A maximum of 3.78 m of out-of-plane tip deflection leads to the danger of a tower strike. And a positive tip deflection of 0.07 m in the in-plane direction indicates that the blade goes against its natural behavior and against the inertial loads while rotating. Continuous monitoring of wind conditions is a must, to put the turbine on brake in cases of gusts and severe turbulence. In areas of high turbulence, downwind turbines can provide a better alternative to allow blade deflections without the danger of tower strikes. Doi: 10.28991/ESJ-2023-07-01-012 Full Text: PD

Structural Dynamics of AWT-27 Wind Turbine Blade

Wind energy is one of the world’s current leading renewable energy resources. One of the major aspects of studying wind turbines is the structural dynamics for the turbine structure including blades and support structure. In the current work, the blades of the Advanced Wind Turbine (AWT-27) are investigated in a dynamic approach. Different wind fields have been generated for the study to provide different Design Load Conditions (DLCs). Three laminar wind velocities of 5 m/s, 12 m/s, and 17 m/s were simulated. Turbulent wind flow fields have also been generated at the three standard classes A, B and C of high, medium, and low turbulence intensities respectively. The generated wind fields were used as inputs to calculate the aerodynamic loads for each wind condition using the Blade Element Momentum (BEM) theory. Aerodynamic loads have been calculated, namely, the shear force on five different locations along the blade length. Results of the simulation are summarized such that the shear forces at the blade root, 30%, 50%, 70% of the blade length are known for each wind condition. The summary serves as a guide for further optimization of the blade structural design

Low-Cost, Low-Weight Test Rig Design for a Laboratory-Scale Twin Rotor Wind Turbine

Multi-Rotor Wind Turbine (MRWT) has been proven advantageous over Single-Rotor Wind Turbine (SRWT) in many aspects. In order to study the performance of MRWT over SRWT, this work presents a low-cost and low-weight design for a test rig for laboratory-scale wind turbine configurations. The configurations under study are a single-rotor, and a twin-rotor of the same size with a diameter of 30 cm. Aerodynamic loads have been calculated using the Blade Element Momentum (BEM) method, then the loads were used for stress analysis over the test rig proposed. The test rig is designed on Solidworks and the aerodynamic and inertial loads were applied for static structural analysis. The analysis showed that both configurations are safe against failure and the deflections were reasonable to ensure low vibrations which may affect the turbine performance. The single-rotor configuration test-rig is about 16 gm in mass, with a 1.67 factor of safety, while the twin-rotor configuration weighs 360 gm with a factor of safety of 3.7

Solar Chimney Power Plants: A Mini Review

The main investigations of a novel solar thermal application known as SCPP are summarized in this paper. It is a method of producing electricity from solar energy that relies on the fact that air rises when it is heated. An adequate position within a tall chimney can be utilized to position a turbine to turn it, creating an updraft that can be used to generate power. This system\u27s specifications, design, construction, and use are all covered in the paper along with experimental and analytical research related to it. It also emphasizes the development and execution of SCPP programs

Aeroelastic Analysis of a Coplanar Twin-Rotor Wind Turbine

Multi-rotor system (MRS) wind turbines can be a competitive alternative to large-scale wind turbines. In order to address the structural behavior of the turbine tower, an in-house aeroelastic tool has been developed to study the dynamic responses of a 2xNREL 5MW twin-rotor configuration wind turbine. The developed tool has been verified by comparing the results of a single-rotor configuration to a FAST analysis for the same simulation conditions. Steady flow and turbulent load cases were investigated for the twin-rotor configuration. Results of the simulations have shown that elasticity of the tower should be considered for studying tower dynamic responses. The tower loads, and deformations are not straightforward with the number of rotors added. For an equivalent tower, an additional rotor will increase the tower-top deflection, and the tower-base bending moment both in the fore-aft direction will be more than doubled. The tower torsional stiffness becomes a crucial factor in the case of a twin-rotor tower to avoid a severe torsional deflection. Tower natural frequencies are dominant over the flow conditions in regards to the loads and deflections

Stability of dental implants placed in healed bony sites of hyperlipidemic patients: A case series

Background: The effect of elevated levels of serum fats ­­-hyperlipidemia- on the long-term implant stability and bone quality has been heavily examined in animal-model studies. This human-based case series is the first clinical study which aimed at clinical and radiographic evaluation of dental implant stability and the changes in bone density in patients with high lipid profile. Materials and Methods: Twelve female patients, each had a single healed bony site which indicated for implantation together with high serum fasting (Low-density lipoprotein) LDL level (≥160 mg/dl) were included in this study. The clinical implant stability values (ISQ) which were measured using the Resonance Frequency Analysis (RFA) method, and CBCT changes were recorded at baseline and six months post-implant insertion. Results: All patients showed implant success after six months. There was a significant increase of implant stability after 6 months from (65.92 ± 6.39 ISQ) to (74.42±6.20 ISQ) (p<0.001)

System identification, fuzzy control and simulation of a kite power system with fixed tether length

In wind energy research, airborne wind energy systems are one of the promising energy sources in the near future. They can extract more energy from high altitude wind currents compared to conventional wind turbines. This can be achieved with the aid of aerodynamic lift generated by a wing tethered to the ground. Significant savings in investment costs and overall system mass would be obtained since no tower is required. To solve the problems of wind speed uncertainty and kite deflections throughout the flight, system identification is required. Consequently, the kite governing equations can be accurately described. In this work, a simple model was presented for a tether with a fixed length and compared to another model for parameter estimation. In addition, for the purpose of stabilizing the system, fuzzy control was also applied. The design of the controller was based on the concept of Mamdani. Due to its robustness, fuzzy control can cover a wider range of different wind conditions compared to the classical controller. Finally, system identification was compared to the simple model at various wind speeds, which helps to tune the fuzzy control parameters.</p

System identification, fuzzy control and simulation of a kite power system with fixed tether length

In wind energy research, airborne wind energy systems are one of the promising energy sources in the near future. They can extract more energy from high altitude wind currents compared to conventional wind turbines. This can be achieved with the aid of aerodynamic lift generated by a wing tethered to the ground. Significant savings in investment costs and overall system mass would be obtained since no tower is required. To solve the problems of wind speed uncertainty and kite deflections throughout the flight, system identification is required. Consequently, the kite governing equations can be accurately described. In this work, a simple model was presented for a tether with a fixed length and compared to another model for parameter estimation. In addition, for the purpose of stabilizing the system, fuzzy control was also applied. The design of the controller was based on the concept of Mamdani. Due to its robustness, fuzzy control can cover a wider range of different wind conditions compared to the classical controller. Finally, system identification was compared to the simple model at various wind speeds, which helps to tune the fuzzy control parameters.Wind EnergyDelft University Wind energy research institut