In this paper, the performances of horizontal axis tidal turbines with three different blade pitching angles, i.e., 50°, 60° and 70°, have been evaluated using STAR-CCM+. The numerical simulation results show that the larger the pitch angle is, the greater the pressure difference between the upstream and the downstream surface of the blade is, and the pitch angle is greatly affected by the force on the impeller in the X axis direction of the incoming flow. When the pitch angle is increased from 50° to 60°, the impeller rotation speed increases by 33% and the average kinetic energy acquired increases by 77%.
With the rapid development of the global economy and technology, the demand for energy in human society is increasing. Fossils, coal and other traditional energy sources are facing a situation of imminent depletion after long-term high-intensity mining and consumption by human beings. The long-term large-scale use of fossil energy has led to a series of problems such as environmental pollution, global warming, and rising energy costs (Chen,2019), and the development and utilization of renewable energy has become one of the importance measures for the sustainable development of human society. Tidal energy and other marine energy sources have the advantages of strong regularity, predictability and high energy density. The horizontal axis power flow energy turbine as the core device for converting power flow energy into electrical energy has high energy acquisition efficiency and good self-starting performance (Wang, 2006; Gao, 2016; Schonbom, 2007; Khan, 2009), and has been widely used. For horizontal axis tidal turbine units, the study of the influence of the pitch angle of the power flow turbine on the hydrodynamic power of the impeller can provide an important reference basis for the design of the turbine control system (Gu, 2019).
Yonglin Li (2010) conducted velocity analysis and force analysis on the blades of vertical axis ocean current power generation turbines, and on the basis of this analysis, a preliminary pitch design scheme was proposed, and it was found that the scheme could improve the hydrodynamic performance of vertical axis ocean current power generation turbines through verification. Zhe Xie (2011) designed and produced a 1kW horizontal axis pitch turbine prototype, and conducted efficiency experiments based on flow rate and pitch angle turbine, which verified the advantages of low starting flow rate and high efficiency compared with fixed pitch turbine. De Jesus Henriques et al (2016) studied the effect of pitch angle on horizontal shaft power flow turbines considering the coexistence of wave currents, and found that increasing the pitch angle can effectively reduce the effect of waves on water turbines.
