Estimating the Aerodynamic Coefficients of a Savonius Rotor Blade Profile Developed Through the Simplex Search Method

2021 ◽  
Author(s):  
Man Mohan ◽  
Divyeshkumar D. Kansagara ◽  
Deepak Sharma ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Simulations ◽  
Rotor Blade ◽  
Aerodynamic Drag ◽  
Search Method ◽  
Small Scale ◽  
Blade Profile ◽  
Savonius Rotor ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Cubic Spline Curve

Abstract The Savonius rotor, a type of vertical-axis wind turbine, seems to be promising for small-scale power generation. Most of the studies conducted so far have focused on the evaluation of torque and power coefficients (CT, CP) of the rotor. This paper aims at analyzing the aerodynamic drag and lift coefficients (CD, CL) of a Savonius rotor blade profile that is generated by the simplex search method to maximize its CP. The optimization is carried out by coupling the numerical simulations with the simplex search method. The optimized blade profile thus obtained is symmetric about its axis, where one half is created through a natural cubic spline curve using three points. Two-dimensional (2D) unsteady numerical simulations have been conducted by adopting ANSYS FLUENT solver to examine the CD and CL of the optimized blade profile at an inlet air velocity of 7.30 m/s. The shear stress transport (SST) k-ω turbulence model is used to solve the transient Reynolds-averaged Navier-Stokes (RANS) equations. The aerodynamic analysis is performed over a range of tip speed ratios (TSRs). The total pressure, velocity magnitudes, and the turbulent intensity contours of the optimized blade profile are generated and studied at different angles of rotation. The CD and CL of the blade profile are investigated for a complete rotation with an increment of 1°. At TSR = 0.8, the optimized profile shows a CDmax of 1.91 at an angle of rotation of 54°, while CDmin is found to be 0.45 at an angle 147°.

Savonius Wind Turbine Blade Profile Optimization by Coupling CFD Simulations With Simplex Search Technique

2019 ◽  
Author(s):  
Ankit Agrawal ◽  
Divyeshkumar D. Kansagara ◽  
Deepak Sharma ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Optimization Technique ◽  
Low Noise ◽  
Blade Profile ◽  
Search Technique ◽  
Cfd Simulations ◽  
Simplex Search ◽  
Wide Range ◽  
Cubic Spline Curve

Abstract The Savonius rotor, a drag-based vertical axis wind turbine, is characterized by its design simplicity, low noise level, self-starting ability at low wind speed and low cost. However, its low performance is always a major issue. One of the remedies of this issue is to design an optimized rotor blade profile, which has mostly been developed through trial and error approach in the literature. In this paper, an optimum blade profile is obtained by maximizing its power coefficient (CP) by coupling CFD simulations of a rotor blade profile with the simplex search technique. Since the blade profile is symmetric about its axis, half of the blade geometry is created through natural cubic spline curve using three points. Two of them are kept fixed, whereas the other one is changed through optimization technique in its every iteration using MATLAB platform. In every iteration, the blade profile is meshed using ANSYS ICEM CFD. The analysis of the blade profile is performed through ANSYS Fluent by using shear-stress transport k-ω turbulence model. A finite volume method based solver is used to solve the transient 2D flow around the wind turbine. The optimum profile of the blade is compared with the conventional profile over a wide range of tip speed ratios (TSRs) in order to check its feasibility for practical applications. The optimum blade profile is found to be better than the semicircular blade in the range of TSR = 0.6–1.

An Efficient Hybrid Evolution Strategy Algorithm with Direct Search Method for Global Optimization

2019 ◽  
Vol 9 (3) ◽  
pp. 63-78
Author(s):  
Noureddine Boukhari ◽  
Fatima Debbat ◽  
Nicolas Monmarché ◽  
Mohamed Slimane
Keyword(s):  
Global Optimization ◽  
Adaptive Evolution ◽  
Optimization Problems ◽  
Search Method ◽  
Local Solution ◽  
Evolution Strategy ◽  
Direct Search Method ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Restart Strategy

The main purpose of this article is to demonstrate how evolution strategy optimizers can be improved by incorporating an efficient hybridization scheme with restart strategy in order to jump out of local solution regions. The authors propose a hybrid (μ, λ)ES-NM algorithm based on the Nelder-Mead (NM) simplex search method and evolution strategy algorithm (ES) for unconstrained optimization. At first, a modified NM, called Adaptive Nelder-Mead (ANM) is used that exhibits better properties than standard NM and self-adaptive evolution strategy algorithm is applied for better performance, in addition to a new contraction criterion is proposed in this work. (μ, λ)ES-NM is balancing between the global exploration of the evolution strategy algorithm and the deep exploitation of the Nelder-Mead method. The experiment results show the efficiency of the new algorithm and its ability to solve optimization problems in the performance of accuracy, robustness, and adaptability.

Inverse Heat Transfer Analysis of Porous Extended Surface Using Simplex Search Method

2013 ◽  
Author(s):  
Rohit Kumar Singla ◽  
Ranjan Das ◽  
Arka Bhowmik ◽  
Ramjee Repaka
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Measurement ◽  
Thermal Conditions ◽  
Search Method ◽  
Heat Transfer Analysis ◽  
Critical Parameters ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Extended Surface

This work deals with the application of the Nelder-Mead simplex search method (SSM) to study a porous extended surface. At first, analytical expression for calculating the local temperature field has been derived using an implicit Runge-Kutta method. The heat transfer phenomenon is assumed to be governed by conductive, naturally convective and radiative heat transfer, whereas the diffusion of mass through the porous media is also taken into account. Then, using the SSM, critical parameters such as porosity, permeability, and thermal conductivities of the extended surface have been predicted for satisfying a prescribed temperature field. It is found that many alternative solutions can meet a given thermal requirement, which is proposed to offer the flexibility in selecting the material and regulating the thermal conditions. It is observed that the allowable error in the temperature measurement should be limited within 5%. It is also found that even with few temperature measurement points, very good reconstruction of the thermal field is possible using the SSM.

A fin design employing an inverse approach using simplex search method

2013 ◽  
Vol 49 (7) ◽  
pp. 1029-1038 ◽  
Author(s):  
Ranjan Das ◽  
Ashis Mallick ◽  
K. T. Ooi
Keyword(s):  
Search Method ◽  
Inverse Approach ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Fin Design
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