Power Optimization of NACA 0018 Airfoil Blade of Horizontal Axis Wind Turbine by CFD Analysis

Introduction

Reducing carbon dioxide emissions is a major contributing factor in alternative energy proposals. In the United State (US) average fuel mix; about 1.5 pounds of CO₂ are emitted for every kilowatt-hour that is generated. Electricity consumption accounted for more than 2.3 billion tons of CO₂ in 2006. This accounted for 39.5 percent of the total emissions from human resources, according to the US Department of Energy. Coal-fired plants alone released over1.9 billion tons, which is one-third of the US total. The US Department of energy also projects that CO₂ emissions from power generation will increase by 19 percent between 2007 and 2030. This is due to new or expanded coal plants. A single 750 KW wind turbine produces roughly 2 million kilowatt hours of electricity annually (James, 2009). Generation of power from renewable energy resources has been extensively increased in several countries due to environmental issues and fossil energy trouble. In which the high generation level of renewable resources gives new opportunities and challenges for power sector (Alhelou et al., 2015; Alhelou & Golshan, 2016). One problem is that wind energy can only be produced when nature supplies sufficient wind. This is not a problem for most countries, which are connected to big grids and can, therefore, buy electricity from the grid in the absence of wind. It is, however, an advantage to know in advance what resources will be available in the near future so that conventional power plants can adapt their production. Now a days in upcoming smart grids, keep the sense of balance among the electrical demand and production. Electric energy would be the main concern due to the uncertainties of both requirement and production of electrical energy from renewable resources (Alhelou et al., 2018; Makdisie et al., 2018). Reliable weather forecasts are desirable since it takes some time for a coal-fired power plant to change its production. Combining wind power with hydropower would be perfect since it takes almost no time to open or close a valve at the inlet to a water turbine and water can be stored in the reservoirs when the wind is sufficiently strong (Spera, 1994). Wind machine has adopted the technology developed for the construction of airplane wings and airplane propeller blades and added some ingenious ideas of their own leading to a new and unique specialized technology. Wind machines operate in an environment totally different from the airplane wings characterized by continuously changing wind speeds and direction. Since the power contained in a moving air stream is proportional to the square of the rotor diameter and to the cube of the wind speed, the rotor blades must be carefully designed in order to optimally extract this power and convert it into torque that drives the electrical generator. Wind turbines come in different sizes and types, depending on power generating capacity and the rotor design deployed. Small wind turbines with output capacities below 10 kW are used primarily for residences, telecommunications dishes, and irrigation water pumping applications. The major responsibility of a power system is to constantly provide the demanded electric energy with a suitable value of service. When the production is lower/higher than the requirement, the frequency will go under/above the nominal value, to maintain the power balance the power system is used (Fini et al., 2016).

Main objective of this article is to obtain optimum power output. Wind energy presents several challenges in order to generate electricity. Power produced from the wind depends on wind velocity. So, at constant wind speed, constant power can be obtained. If constant wind speed is not there at that time constant power can be obtained by providing mechanism, i.e. by changing the blade angle up to certain limit. This work seeks to develop the design optimization for wind turbine rotor blade. By analysis of the rotor blade shows which blade angle give optimum power output. CFD simulation of blade helps to predict power, pressure distribution over the surface of airfoil and force acting on it. There are various blade simulation software’s commercially available in the market. In this work Ansys CFX software was used for simulation.