Suresh Raj, Aaron Basil Raj
(2021)
Aerodynamics And Performance Of Variable Pitch Vertical Axis Turbines At Low Tip Speed Ratios.
Project Report.
Universiti Sains Malaysia, Pusat Pengajian Kejuruteraan Aeroangkasa.
(Submitted)
Abstract
The shift to renewable energy is imminent to aid the reduce its
total carbon footprint and fight off global warming. Wind and hydrokinetic energy
have great potential to replace the depleting reserves of fossil fuels. With its
scalability and omnidirectional advantage, vertical-axis turbines are a great
renewable energy source for off-grid and rural areas. Although the vertical
characteristics of the turbine look promising, it is known to have far lower
performance than its horizontal counterpart. This research investigates the detailed
aerodynamic study of lift and drag contribution on the turbine blades with variablepitch
blade through numerical simulation via an open-source software called Qblade.
The problems to be investigated in this research are the effects of pitch angle on the
aerodynamic contribution of the blades and the variable-pitch model to improve
performance over various operating ranges. It is suggested that applying pitch angle
to the blade at a controlled amount can help maintain a constant steady angle of
attack, which can be altered to extract the most performance. The effects of blade
pitching would be studied to determine the instantaneous aerodynamic loadings, the
tangential and normal forces while ultimately referencing the average power
coefficient, for overall performance. Variable-pitch blade will be employed in this
study to compare and determine the benefit and drawback of the pitching method for
vertical-axis turbine performance. The investigation would be carried out by a series
of numerical simulations of a single-bladed Darrieus turbine in Qblade using the
Lifting Line Free Vortex Wake (LLT) module. A single blade is chosen to solely study the complete aerodynamic loading without compromising the effects of
multiple blades and complex wakes. The blade
Blade Designer module with a NACA 0018 airfoil profile and experimentally tested
extrapolated airfoil polar data to ensure realistic and accurate data. Validation
studies are then carried out by comparing the simulated results from Qblade to
Computational Fluid Dynamics (CFD) solution and experimental tests to ensure the
method and model used in the simulation are accurate and trustworthy. The data
obtained from Qblade is then processed in MATLAB to observe the aerodynamic
loads on the blade and the aerodynamic contribution to the power produced in a
turbine rotation. A fine-tuned variable-pitch blade will be created through MATLAB
and implemented via Simulation Input Files in a turbine model in Qblade. LLT
simulation would be carried out for low tip-speed ratios of 0.75, 1.0, 1.6, 2.0, and
2.5, allowing us to observe the impact of different tip-speed ratios on variable-pitch
blade.
Actions (login required)
 |
View Item |
