Design of Wind Turbine Blade with Thick Airfoils and Flatback and its Aerodynamic Characteristic
large-scaled blade has posed many problems related to design and production. After introducing the features of blade with thick airfoils and flatback, based on relevant parameters of Huaren 100 kW wind turbine, the paper designed blade with thick airfoils and flatback, introduced blade parameter design, and analyzed the aerodynamic performance of blades using GH bladed software, obtaining the relationship between power output of wind turbine with blade tip speed ratio Cp. Furthermore, it analyzed the aerodynamic performance of original design blades, modified blades and Huaren 100 kW blades, and assessed the aerodynamic performance of modified blade.
Air Ducted Blade Design for Horizontal Axis Wind Turbines

 Background: Medium and small-scale wind turbines with no pitch control are cheaper than their controlled equivalents but are much more affected by aerodynamic stall, and local boundary layer separation occurs on the blade when critical wind speed is exceeded. As a result, they produce relatively low power. In this study, the delay of separation of the boundary layer from the surface was investigated by increasing the kinetic energy of the low-momentum fluid behind the surface utilizing the airflow from the air ducts added on the blade. Methods: To obtain the optimum performance from the blade, a computer-aided optimization study was conducted by taking the slope, diameter, number, and angle of attack parameters of the air ducts. The response surface methodology, a goal-oriented and multi-purpose method, was used as an optimization method to provide the best possible design according to the constraints and targets set for the parameters. Results: Optimum parameter values were determined using computational fluid dynamics analysis, and air ducted blade design was compared with the air duct-free blade design, and as a result, the power coefficient obtained from the blade was improved between 3.4% and 4.4% depending on wind speed. Conclusions: Opening air ducts up to a critical number of ducts increase viscous forces. this provides more power from the rotor. On the other hand, with the extra airflow coming from the air ducts, the flow separation behind the wing is delayed and the stall effect is shifted to higher wind speeds and the rotor can work for a longer time at nominal power. Besides, since all this is done with passive flow control, a remarkable increase in annual electricity production from the turbine is provided.
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.