Experimental and Numerical Investigation Into Vertical Axis Water Turbine Self-Starting Phenomenon

Abstract

In rural areas and isolated regions of the world, it is often difficult to obtain reliable access to electricity. A solution often exploited is the use of diesel generators to power homes but that has its negative effects on climate change. In this study, an alternative solution is being investigated, which involves the use of water turbines. For low head applications such as rivers, hydrokinetic turbines are used to harness the kinetic energy in rivers. There are two types of hydrokinetic turbines: horizontal and vertical axis water turbines. The turbine studied in this paper is the Darrieus type vertical axis water turbine (VAWT) which has three straight blades. Darrieus type VAWT primarily use lift forces to operate. Advantages of vertical axis water turbines are simple construction, low cost, and being able to self-orient. However, the Darrieus VAWT has several disadvantages like self-starting problem, low coefficient of performance, shaking, debris accumulation, and cavitation. In this study, the effect of using thermoplastic polyurethane blades with varying levels of flexibility have been investigated to remedy the self-starting problem. For blade profile, S1046 airfoil is selected. 3-D numerical models were created by using time-accurate Reynolds-averaged Navier Stokes (RANS) commercial solver (ANSYS Fluent 2019 R3). Experimental results show that turbine with lower blade hardness starts to rotate at 0.34m/s while the turbine with higher blade hardness experiences rotation at 0.51m/s.