A Review of Solidity and Rotor Size Effects on Water-Pumping Windmills

2021 ◽  
Author(s):  
Omar Abdulkareem Qasim ◽  
Ahmet Samancı
Keyword(s):  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Wind Speeds ◽  
Water Pumping ◽  
Horizontal Axis Wind Turbines ◽  
Ideal Number ◽  
Design Requirements ◽  
Great Possibility ◽  
Low Wind Speeds ◽  
Different Diameters

The windmill is one of the important applications of wind energy and it is one of the best and the easiest ways to manipulate this wind power and use it for water pumping. The best feature of windmills is their high solidity, which gives high torque at the starting. Therefore, they will be able to lunch at low wind speeds like 2 m/s which gives a great possibility of utilizing, especially in the agricultural countries. This feature has been the focus of attention of researchers and developers over the long years. There are several factors affected by it, the most prominent of which is the number of blades and the diameter of the rotor. Some researchers have tested with different models of different diameters and others did on different numbers of blades. The challenge is how to find a model with an ideal number of blades and diameter that can give us the highest torque value under low wind conditions. In this paper, the multi-bladed horizontal axis wind turbines, which are used for water pumping, are discussed. Besides, the literature review is described, which presented the basic design requirements for windmill rotors as solidity, diameter, and tip speed ratio, also information given about materials that used in manufacture. The investigations of this paper are focused on the effect of the number of blades to reach the main goal and the best performance at located wind speeds.

Experimental and Numerical Assessment of Cross Flow Vertical Axis Wind Turbine

2019 ◽  
Author(s):  
Sivamani Seralathan ◽  
Micha Premkumar Thomai ◽  
Rian Leevinson Jayakumar ◽  
Basireddy Venkata Lokesh Reddy ◽  
Hariram Venkatesan
Keyword(s):  
Wind Turbine ◽  
Renewable Energy Sources ◽  
Cross Flow ◽  
Experimental Investigations ◽  
Speed Ratio ◽  
Positive Interaction ◽  
Polar Plot ◽  
Tip Speed Ratio ◽  
Wind Speeds ◽  
Low Wind Speeds

Abstract Due to increase in energy demand along with environmental awareness, the attention is shifting towards renewable energy sources. A wind turbine developed from Banki water turbine is used in this study as it starts at low-wind speeds and has high starting torque. Experimental investigations are carried out on a test rig equipped with open jet wind tunnel with wind velocity varying from 7 to 11 m/s. Later, 3D steady-state numerical analyses are performed using ANSYS CFX for better understanding of the flow physics of cross flow VAWT. The experimental investigations revealed that cross flow VAWT has a good self-starting ability at relatively low-wind speeds. A peak power coefficient (Cp, max) value of 0.059 is observed for the tip speed ratio (λ) of 0.30. As the tip speed ratio is raised further, the Cp value is observed to decrease gradually. The numerical simulations reveal the reason for the drop in Cp value. This is due to lessening of positive interaction between the flow and cross flow VAWT blades at higher λ due to vortex formation. The torque coefficient is found to decrease almost linearly from a peak value of around 0.49 at λ = 0 to a value of 0 around λ = 0.60. Polar plot between angle and torque shows that torque output of the turbine is nearly same in all directions which reinforce the potency of cross flow VAWT to be omni-directional as it produces the same performance regardless of wind directions.

Effect of Slotted Angle on Savonius Wind Turbine Performance

2021 ◽  
Vol 104 ◽  
pp. 83-88
Author(s):  
Rahmat Wahyudi ◽  
Diniar Mungil Kurniawati ◽  
Alfian Djafar
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Electrical Energy ◽  
Speed Ratio ◽  
Angle Variation ◽  
Wind Speeds ◽  
Turbine Performance ◽  
Savonius Wind Turbine ◽  
Low Wind Speeds

The potential of wind energy is very abundant but its utilization is still low. The effort to utilize wind energy is to utilize wind energy into electrical energy using wind turbines. Savonius wind turbines have a very simple shape and construction, are inexpensive, and can be used at low wind speeds. This research aims to determine the effect of the slot angle on the slotted blades configuration on the performance produced by Savonius wind turbines. Slot angle variations used are 5o ,10o , and 15o with slotted blades 30% at wind speeds of 2,23 m/s to 4,7 m/s using wind tunnel. The result showed that a small slot angle variation of 5o produced better wind turbine performance compared to a standard blade at low wind speeds and a low tip speed ratio.

scholarly journals Strategies for Enhancing the Low Wind Speed Performance of H-Darrieus Wind Turbine—Part 1

2019 ◽  
Vol 1 (1) ◽  
pp. 185-204 ◽  
Author(s):  
Palanisamy Mohan Kumar ◽  
Krishnamoorthi Sivalingam ◽  
Teik-Cheng Lim ◽  
Seeram Ramakrishna ◽  
He Wei
Keyword(s):  
Wind Speed ◽  
Poor Performance ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Wind Speeds ◽  
Low Wind Speed ◽  
Viable Solution ◽  
Speed Performance ◽  
Low Wind Speeds ◽  
Starting Characteristics

Small wind turbines are key devices for micro generation in particular, with a notable contribution to the global wind energy sector. Darrieus turbines, despite being highly efficient among various types of vertical axis turbines, received much less attention due to their starting characteristics and poor performance in low wind speeds. Radically different concepts are proposed as a potential solution to enhance the performance of Darrieus turbine in the weak wind flows, all along the course of Darrieus turbine development. This paper presents a comprehensive review of proposed concepts with the focus set on the low wind speed performance and critically assessing their applicability based on economics, reliability, complexity, and commercialization aspects. The study is first of its kind to consolidate and compare various approaches studied on the Darrieus turbine with the objective of increasing performance at low wind. Most of the evaluated solutions demonstrate better performance only in the limited tip speed ratio, though they improve the low wind speed performance. Several recommendations have been developed based on the evaluated concepts, and we concluded that further critical research is required for a viable solution in making the Darrieus turbine a low speed device.

A Study on Water Pumping by Using a Small Multi-Blades Windmill for Used in a Remote Area

2013 ◽  
Vol 724-725 ◽  
pp. 527-530
Author(s):  
Yuttachai Keawsuntia
Keyword(s):  
Wind Velocity ◽  
Life Time ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Pump System ◽  
Tip Speed Ratio ◽  
Water Pumping ◽  
Overall Efficiency ◽  
Water Base ◽  
Rotor Model

The objective of this research is to study the small multi-blades windmill for water pumping by using a studying performance of windmill which has a curvature plate ratio of 0.07 and determine overall efficiency and evaluate economic of the system. The results from the test run of windmill rotor model in the wind tunnel at a wind velocity of 3 m/s, the windmill give maximum power coefficient of 0.296 at a tip speed ratio of 1.18. The results from the test run of the windmill-pump system at 2 m head have an overall efficiency of 0.239 at the wind velocity of 1.2 m/s. The output of 2.38 L/min, which implies a rate of return for water pumping at 0.038 USD per cubicmetre of water base on 10 year-life time of windmill.

scholarly journals Wake Expansion and the Finite Blade Functions for Horizontal-Axis Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7653
Author(s):  
David Wood
Keyword(s):  
Radial Velocity ◽  
Wind Turbines ◽  
Loss Factor ◽  
Axial Direction ◽  
Horizontal Axis ◽  
Speed Ratio ◽  
Tip Speed Ratio ◽  
Constant Pitch ◽  
Horizontal Axis Wind Turbines ◽  
Blade Element

This paper considers the effect of wake expansion on the finite blade functions in blade element/momentum theory for horizontal-axis wind turbines. For any velocity component, the function is the ratio of the streamtube average to that at the blade elements. In most cases, the functions are set by the trailing vorticity only and Prandtl’s tip loss factor can be a reasonable approximation to the axial and circumferential functions at sufficiently high tip speed ratio. Nevertheless, important cases like coned or swept rotors or shrouded turbines involve more complex blade functions than provided by the tip loss factor or its recent modifications. Even in the presence of significant wake expansion, the functions derived from the exact solution for the flow due to constant pitch and radius helical vortices provide accurate estimates for the axial and circumferential blade functions. Modifying the vortex pitch in response to the expansion improves the accuracy of the latter. The modified functions are more accurate than the tip loss factor for the test cases at high tip speed ratio that are studied here. The radial velocity is important for expanding flow as it has the magnitude of the induced axial velocity near the edge of the rotor. It is shown that the resulting angle of the flow to the axial direction is small even with significant expansion, as long is the tip speed ratio is high. This means that blade element theory does not have account for the effective blade sweep due to the radial velocity. Further, the circumferential variation of the radial velocity is lower than of the other components.

scholarly journals Investigation of the Solidity Ratio in a Horizontal Wind Turbine

2021 ◽  
Vol 1 (2) ◽  
Author(s):  
Süleyman Tekşin ◽  
Mert Kurt
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Horizontal Wind ◽  
Speed Ratio ◽  
Horizontal Axis Wind Turbine ◽  
Generator System ◽  
Wind Speeds ◽  
Solidity Ratio ◽  
Different Diameters ◽  
Work Done

A wind turbine-generator system; Parameters such as wind speed, turbine blade diameter, number of blades, turbine height, tip speed ratio and solidity ratio are affected. In this study, horizontal axis wind turbine with diameter of 130 cm and blade solidity ratio values of 7%, 8,6% and 9,8% were constructed and the tests were made according to different blade speed ratios. The required blades were obtained from PVC pipes of different diameters. The experimental study was actualized in Erciyes University Mechanical Engineering, Engines Laboratory. For each profile, blade rotational speeds and wind speeds at various distances have been studied. It has been determined that the wind speed is reduced by the distance difference and accordingly the number of blade speed is decreased visibly. In the wing profiles with different blade solidity ratios resulting from the work done, the wing structure with the solidity ratio of 8.6% gave the best performance. CL and CD coefficients of the profiled specimens were analyzed by FLUENTTM, a program of computational fluid dynamics. One of the factors that should be taken into consideration in the production of wind turbines is the blade solidity ratio.

Aerodynamic Design and Wind Tunnel Tests of Small-scale Horizontal-axis Wind Turbines for Low Tip Speed Ratio Applications

2022 ◽  
pp. 1-34
Author(s):  
Ojing Siram ◽  
Neha Kesharwani ◽  
Niranjan Sahoo ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Pitch Angle ◽  
Horizontal Axis ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Small Scale ◽  
Wind Tunnel Tests ◽  
Tip Speed Ratio ◽  
Horizontal Axis Wind Turbines

Abstract In recent times, the application of small-scale horizontal axis wind turbines (SHAWTs) has drawn interest in certain areas where the energy demand is minimal. These turbines, operating mostly at low Reynolds number (Re) and low tip speed ratio (λ) applications, can be used as stand-alone systems. The present study aims at the design, development, and testing of a series of SHAWT models. On the basis of aerodynamic characteristics, four SHAWT models viz., M1, M2, M3, and M4 composed of E216, SG6043, NACA63415, and NACA0012 airfoils, respectively have been developed. Initially, the rotors are designed through blade element momentum theory (BEMT), and their power coefficient have been evaluated. Thence, the developed rotors are tested in a low-speed wind tunnel to find their rotational frequency, power and power coefficient at design and off-design conditions. From BEMT analysis, M1 shows a maximum power coefficient (Cpmax) of 0.37 at λ = 2.5. The subsequent wind tunnel tests on M1, M2, M3, and M4 at 9 m/s show the Cpmax values to be 0.34, 0.30, 0.28, and 0.156, respectively. Thus, from the experiments, the M1 rotor is found to be favourable than the other three rotors, and its Cpmax value is found to be about 92% of BEMT prediction. Further, the effect of pitch angle (θp) on Cp of the model rotors is also examined, where M1 is found to produce a satisfactory performance within ±5° from the design pitch angle (θp, design).

Analytical and experimental study of the integral aerodynamic characteristics of low-speed wind turbines

2014 ◽  
Vol 118 (1209) ◽  
pp. 1229-1244 ◽  
Author(s):  
M. Valiev ◽  
R. Stepanov ◽  
V. Pakhov ◽  
M. Salakhov ◽  
V. Zherekhov ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Power Efficiency ◽  
Wind Farm ◽  
Aerodynamic Characteristics ◽  
Optimal Conditions ◽  
Low Speed ◽  
Wind Speeds ◽  
Horizontal Axis Wind Turbines ◽  
Low Wind Speeds ◽  
Theoretical Results

Abstract This paper proposes a new wind turbine concept suitable for low-speed winds. The design is studied using a combination of wind-tunnel experimentation and aerodynamic theory. After processing the experimental results, and after comparison with theory, the optimal conditions for the operation of the turbine are identified. Experimental and theoretical results suggest that the design offers a realistic alternative to conventional horizontal axis wind turbines. In addition, the proposed turbine has good power efficiency at low wind speeds, and is suitable for deployment in areas not yet favoured by wind farm developers.

On the Effect of Altitude on the Performance of a Small Wind Turbine Blade

2014 ◽  
Author(s):  
Abolfazl Pourrajabian ◽  
Masoud Mirzaei ◽  
Reza Ebrahimi ◽  
David Wood
Keyword(s):  
Wind Turbine ◽  
Objective Function ◽  
Output Power ◽  
Geometry Optimization ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Wind Speeds ◽  
Starting Time ◽  
Small Wind Turbine ◽  
Low Wind Speeds

This study deals with the effect of the altitude on the performance of a Small Wind Turbine (SWT) blade. Four potential regions of wind energy with altitudes up to 3,000 m were selected and a three-bladed, 2 m diameter small HAWT was designed for those regions. Starting time was combined with output power in an objective function to improve the performance of the turbine at low wind speeds. The goals of the objective function, the output power and the starting performance, were addressed by geometry optimization of the blade which was carried out by the genetic algorithm. The modified Blade-Element Momentum (BEM) theory was applied to calculate the output power and starting time. Results show that the performance of an optimal blade which was optimized for operating at sea level degrades for other regions. That degradation is more important for the starting performance in comparison with the reduction of the power coefficient. To improve the performance of the blade in the considered regions, two redesign procedures were carried out. First, the geometry of the blade was optimized respect to the air density of the regions which led to increase of the power coefficient and the starting time. Much more power was achieved using the second approach in which the tip speed ratio was added to the geometry of the blade as an additional design variable. Results also indicate that the generator resistive torque remarkably puts off the starting of the turbine especially at very high altitudes.

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