A Ffowcs Williams-Hawkings numerical aeroacoustic study of varied and fixed-pitch blades of an H-Rotor vertical axis wind turbine

The effects of sound pressure level at two observation positions of a fixed and varied blade pitch angle at Low-Mach unsteady incompressible Reynolds-Average Navier-Stokes flow approach, on an H-rotor Vertical Axis Wind Turbine. The objective of the study is to compare the noise dissipation and output power/energy of the airfoil blades design of the vertical axis wind turbine in residential zones. The Ffowcs Williams-Hawkings (FHWH) techniques were applied to validate the output noise and vortex shedding of the different angles of attacks (AoA). The study postulated that the time history of the calculated sound pressure level at two observers positions: the aeroacoustic, blade vortex interaction noise, flow separations, dynamic stall experience from varied angled of attacks are found to produces less noise and vortex shedding compared to the fixed angle of attack.

Mixing Efficiency Comparison of Symmetric and Asymmetric Airfoil Blades in a Continuous Stirred Tank Reactor

This study compared mixing efficiencies of the symmetric and asymmetric airfoil blades in a continuous stirred tank reactor (CSTR) at various mixing velocities and angles of attack. The symmetric airfoil blades (NACA0009 and NACA0015) and asymmetric airfoil blades (NACA2414 and NACA4412) were set at different angles of attack and mixing velocities. The tank reactor was equipped with two sets of three airfoil blades at the upper and the lower parts of the stirring shafts at the angles of attack 0 deg, 10 deg, 16 deg, and 20 deg, and the mixing velocities of 80, 110, 140, and 190 rpm. The mixing efficiencies were evaluated from the homogenous appearance of plastic particles (5 mm in diameter) dispersed in water by an image processing technique. The results indicated that the mixing efficiencies of both the symmetric and asymmetric airfoil blades increased with increasing mixing velocities and at the angles of attack 0 deg and 10 deg, and slightly decreased with increasing mixing velocities at the angles of attack 16 deg and 20 deg due to the blade stall and mixing saturation as well as short-circuiting flow from the high flowrate. There was no significant mixing velocity effect on mixing efficiencies at the angles of attack 10 deg, 16 deg, and 20 deg except 0 deg of the symmetric and asymmetric airfoil blade systems. The two asymmetric airfoil blade types gave higher mixing efficiencies than the two symmetric airfoil blade types. The results from this study can be applied for a novel blade design for an efficient mixing flow, which will be beneficial for industrial biogas production.

Study of Leading-Edge Dimple Effects on Airfoil Flow Using Tomographic PIV and Temperature Sensitive Paint

Airfoil blades can experience a significant change of angle of attack during operation cycles, which may lead to static or dynamic stall in various applications. It is unclear how elements distributed at the leading edge would affect the aerodynamic performance and stall behaviors. In the present study, a distributed dimples configuration was investigated and compared to a baseline smooth NACA0015 airfoil at low Reynolds numbers. Two- and four-camera, tomographic particle image velocimetry (PIV), and temperature sensitive paint (TSP) techniques were set up to gather flow and surface information near the curved leading-edge surface and to study flow separation. Results suggest that distributed dimples configuration create abrupt separation leading to stall and induce a similar stall compared to the smooth model. However, the stall is induced more abruptly and with different flow patterns. Results show that patterns of separated shear layer at stalled conditions were enhanced by the current configuration. Effect of these structures on the boundary layer transition were also analyzed based on combined tomographic PIV and TSP measurement techniques.

Perancangan dan Pemodelan Turbin Darrieus untuk Pembangkit Listrik Tenaga Arus Laut (PLTAL)

<em>Sea current energy is one of the new and renewable energy that is currently being developed to replace fossil energy which is starting to deplate its availability. Sea current energy research continues to be developed. One of the studies that can be developed is modeling laboratory-scale sea currents, so that it is necessary to design a model of Sea Current Power Plants that aims to improve the process of understanding the energy. In this design, a model of Sea Current Power Plant with a capacity of 150 Watt is designed using the Darrieus Turbine. The design results some data such as : diameter of 428 mm for turbine rotor, height of 327 mm for turbine rotor, chord length of 0.04 m for 3 NACA 0018 airfoil blades, and a transmission ratio of 1 : 5 for transmission systems using a straight gear gearbox. In addition, the turbine generated 205.5 rpm rotation at flow rate of 1.15 m/s with turbine efficiency of 40%.</em>