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Unsteady CFD simulations on the effects of number of blades on counter rotating wind turbine (CRWT) were carried out in order to investigate the performance and the flow characteristics. In this paper, 2-bladed and 3-bladed CRWT were designed using Blade Element Momentum Theory (BEMT) which comprised of S833, S834, and S835 airfoils. As a comparison baseline, a SRWT model which have similar design with front rotor of the 3-bladed CRWT would be also investigated. It was found that the SRWT had the same rotational speed with the front rotor of the 3-bladed CRWT. There was about 10.24 % and 11.79 % rotational speed reduction of the rear rotor from the front rotor of 2-bladed CRWTs and 3-bladed CRWTs, respectively. Both of 2-bladed CRWT and 3-bladed CRWT have higher total power than SRWT, thereby generating more larger velocity deficits in the wake flow.

In this research, the effect of number of blades (2 and 3) of counter rotating wind turbine (CRWT) were simulated in transient condition to be further analyzed the performance and the fluid flow characteristic formed. The simulations used finite volume method approach with additional turbulance model SST k-omega under transient condition to be analyzed the development of the fluid flow started from idling rotors until rotated on their own steady angular velocities. Results of this research show that 2-bladed CRWT had higher steady angular velocity characteristic than 3-bladed CRWT, both of the front and rear rotors, but 3-bladed CRWT had faster performance in term of time to achieve their steady angular velocities than 2-bladed CRWT during the transient process. In term of mechanical power produced, the 3-bladed CRWT performed better than 2-bladed CRWT, around 10.5% in their own steady angular velocities. This results were supported by velocity deficit flow visualizations and velocity profile in selected regions.

Validity and reliability of end-user computing satisfaction in Indonesian language to measure digital nursing assessment tool Thermodynamic analysis of the effect of reservoir temperature change on the performance of organic rankine cycle system on geothermal power plant Abstract. Nowadays monitoring systems are designed with embedded technology such as Wireless Sensor Network. A communication stack based on IPv6 for low power devices named 6LoWPAN gives a great opportunity for sensor networks to communicate with the Internet using IP. However, with a few differences between the 6LoWPAN protocol stack and IP protocol stack, it is difficult for 6LoWPAN sensor networks to be operated from the Internet directly. In order to be directly connected to IPv6 networks, tunneling is required. Therefore, tunneling process test on 6LoWPAN network to connect to IPv6 networks needs to be done to show how each 6LoWPAN nodes will be accessible through the edge node and IPv6 network. In this research, we have conducted experiments to design the 6LoWPAN networks and test the tunneling process on 6LoWPAN network to connect with IPv6 networks. We have created a 6LoWPAN network with one edge node and two end nodes. The result shows that each node will be accessible using its IPv6 address through the edge after tunneling process is successfully executed. This research can become an insight for further studies on 6LoWPAN protocol stack as a part of the WSN-based monitoring system in movement.