Takuya IWAMURA’s research while affiliated with Tokyo National College of Technology and other places

Wind turbines with a propeller-type rotor on a horizontal axis employ turbine blades have a thickness ratio δ(the ratio of chord length C against maximum thickness T), which is small at the blade tip (thin blade), and is large at the blade root (thick blade). In this study, we focused on the effects of vortex generator on allowing a significant expansion of the operable range to a higher angle of attack that causes a stall. And the flow visualization and velocity distribution around the airfoil were measured and compared with without of vortex generator. This paper examines in detail around the blades affects flow separation from the blade surface and aerodvnamic characteristics associated with stalls.

Various blades are used for fluid machinery such as wind turbines and pumps. This report focuses attention on wind turbine blades. Wind turbine generator systems consisting of wind turbines with propeller-type rotors on a horizontal axis employ turbine blades to effectively catch aerodynamic forces commonly represented by lift and drag. The thickness ratio of the blade is small at the blade tip (thin blade) and is large at the blade root (thick blade). The previous paper proposed that placing a cylindrical rod in front of a blade as a simplified stall control method for controlling the flow around the blade and avoiding stall phenomena improved the flow on the upper surface of the blade and extended the operable range significantly until the angle of attack reached the high attack angle region where a stall occurred. In this paper, a cylindrical rod in front of the thick blade was placed to examine the behavior of flow aro und the blade by using experimental and studied the effect of the cylindrical rod on the control of stall phenomena.

Water hammer pumps can effectively use the water hammer phenomenon for water pumping. They are capable of providing an effective fluid transport method in regions without a well-developed social infrastructure. The results of experiments examining the effect of the geometric form of water hammer pumps by considering their major dimensions have been reported. However, these conventional studies have not fully evaluated pump performance in terms of pump head and flow rate, common measures of pump performance. The authors have focused on the effects on the pump performance of various geometric form factors in water hammer pumps. The previous study examined how the hydrodynamic characteristics was affected by the inner diameter ratio of the drive and lift pipes and the angle of the drive pipe, basic form factors of water hammer pumps. The previous papers also showed that the behavior of water hammer pump operation could be divided into four characteristic phases. The behavior of temporal changes in valve chamber and air chamber pressures according to the air volume in the air chamber located downstream of the lift valve was also clarified in connection with changes in water hammer pump performance. In addition, the effects on water hammer pump performance of the length of the spring attached to the drain valve and the drain pipe angle, form factors around the drain valve, were examined experimentally. This study focuses on the form of the lift valve, a major component of water hammer pumps, and examines the effects of the size of the lift valve opening area on water hammer pump performance. It also clarifies the behavior of flow in the valve chamber during water hammer pump operation.

In recent years, public concern about environmental affair is growing at the same time, wind power generation systems have been common, it is required to improve the efficiency of wind turbine blades, leading to its operational stability and high efficiency. In this study, it is examined if the blade surface roughness affects the flow condition around the wind turbine blades to control the blade performance. Specifically, the flow velocity around blades are measured by using the hot-wire anemometer, so as to identify the flow behavior on the blade surface and behind the blades. As a result, flow separation is decreased because of contain roughness on the blade, and it is clarified that flow behavior on the blade surface and behind the blades is changed due to the blade surface roughness.