Simulation Savonius Wind Turbine with Multi-Deflector Budi Sugiharto 1,2,a , Sudjito Soeparman 2,b , Denny Widhiyanuriyawan 2,c and Slamet Wahyudi 2,d 1) Mechanical Engineering, Faculty of Science and Technology, Sanata Dharma University, Yogyakarta 2) Mechanical Engineering, Faculty of Engineering, Brawijaya University, Malang a sugihartobudi@yahoo.co.id, b sudjitospn@yahoo.com c denny_malang2000@yahoo.com, d slamet_w72@yahoo.co.id Keywords: multi-deflector, CFD, static torque, Coand-like flow, dragging flow, overlap flow Abstract. This paper aims to study the windmill Savonius with multi-deflector. Multi-deflector placed around the windmill, which aims to reduced negative torque to the returning blade and directing the flow of wind to the advancing blade . CFD analysis with ANSYS software. The initial conditions with variation wind speeds 3, 4, 5 and 6 m / s. The result indicated by velocity distribution at positions 0 0 , 45 0 , 90 0 and 135 0 . The largest static torque occurs at position 450 caused by the greater the Coand-like flow, dragging flow and overlap flow. The greater the static torque that occurs with increasing wind speeds. Introduction Savonius a vertical axis windmill that operates due to the drag force on the blades, but it also affects the lifting force of the mechanical power transmitted to the shaft. Savonius windmill has advantages such as simple design and construction, can receive wind from any direction, can work at low wind speeds, large static and dynamic torque but it has low efficiency [1]. Savonius windmill performance can be improved by additional deflector aimed at reducing the negative torque to the returning blades and directing the flow of the advancing blade [2,3,4]. However, Savonius with deflector performance is influenced by the tip clearance between the deflector, the greater the tip clearance so the greater losses that occur [4]. Single deflector has a weakness can only accept wind from the front, when there is a change in wind direction it is necessary to change the deflector position. Multi-deflector overcome this so that the wind direction from anywhere is not a problem. In addition to the multi-deflector can reduce the vortex that occurs behind the windmill. The influence of tip clearance on the static torque and velocity distribution will be observed in the use of multi- deflector. Methodology Simulation using ANSYS software with geometry surface-plane, and the dimensions; in a blade radius (r) 103 mm, blade thickness (t) 5 mm, overlap (o) 31 mm or overlap ratio (o/2r) 0.15, windmill diameter (D) 391 mm. Multi-deflector with the number 8 has a long dimension of 1.5 r and thickness 5 mm. Tip clearance windmill to multi-deflector varied by 0.1 r 0.2 r and 0.3 r. Windmills and multi-deflector coaxial placed in the middle of a wind tunnel shown in Figure 1. The solution using the Pressure-based, steady time, space 2D, Model k - epsilon, Standard Wall Functions, Velocity Pressure Control Coupling with Semi-Implicit Method for Pressure Linked Equation (SIMPLE), discretization Momentum Second Order Upwind and Pressure Standard [5,6,7]. Given boundary condition input variable wind speed are 3, 4, 5 and 6 m / s, and the output of outflow. Applied Mechanics and Materials Submitted: 2015-12-07 ISSN: 1662-7482, Vol. 836, pp 289-293 Accepted: 2016-01-27 doi:10.4028/www.scientific.net/AMM.836.289 Online: 2016-06-01 © 2016 Trans Tech Publications, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, www.ttp.net. (ID: 202.94.83.73-06/04/16,05:46:41)