The integrity of the wind turbine is protected with appropriate design of the blades with safe margin. The blades are the most exposed part of the machine, exposed to air, rust, moisture and friction. therefore during designing such factors have to be incorporated to protect the integrity of blades. The blades are considered as "balanced integration of economic, aerodynamic, structural dynamic, noise, and aesthetic considerations". and their size and shape determines the power generation through wind turbine. The design of the blade is based upon the material, blade number, airfoils, chord and twist distributions. Each of these factors determines the efficiency of the rotary machine. the material of the blade shall govern strength, airfoil geometry shall desired high lift-to-grad ratio and/or blade stiffness. The design of the horizontal wind has been categorised into upwind and downwind configurations. and various additional characteristics i.e. performance enhancers have been included such as diffusers and concentrators.
The modified design of the blades have been introduced which is the three-bladed rotor. this is "industry-accepted configuration". The advantages of such design are related to the modest noise parameters. beside such design has also translated into lower blade fatigue. The selection of the blade number is based upon the stiffness of the blades, aerodynamic efficiency, and tower-shadow impulsive noise. The three-bladed rotor is preferred due to "rotor-noise and aesthetic considerations". It is important to realise that for specific rotor diameter, the three-bladed rotor will have "two-thirds the blade loading of a two-bladed rotor and one-third that of a one-bladed rotor". The three-bladed rotor has "lower impulsive noise resulting from blade loading for either a downwind or upwind tower shadow". In case of two-bladed and one-bladed rotor, the lower aerodynamic efficiency is controlled through "lower solidity and higher tip speeds for a given diameter or power relative to three-bladed rotors". As per general rule, the increase in rotor noise is subject to the higher tip speed. where the "noise is proportional to the fifth power of tip speed".
From technical perspective, the balancing of the rotor is critical exercise and small magnitude of imbalance can lead to excessive vibration on the machine which shall result in the fatal damage. The three-blade rotor are much balanced than two-bladed rotor, "the 120-degree spacing between the blades, rotor dynamics are more benign than for the 180- and 360-degree spacing associated with two- and one-bladed rotor systems, respectively". It has been proven that the three-bladed rotor is reliable, and requires minimum operating and maintenance cost, as compared with the cost incurred by two-bladed and one-bladed rotors.
Airfoils are the critical component of the rotor, the airfoil itself is the blade. The thickness and geometry of blades determines the performance characteristics of the rotor. The airfoil is designed such that laminar flow is developed across the airfoil and low drag is generated. Airfoils developed for high Reynolds numbers experience "significant laminar separation bubbles", such occurrence can lead to substantial damage to the airfoil, and can lead to roughness. The formation of the bubbles is not desirable, because it will "lead to large