Diffuser Shroud Research Articles

1823 大規模風車への適用を目指した新しい風レンズ体の提案(S17-1 風力発電(1),21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

We have developed a new wind turbine (Wind Lens Turbine) which consists of a diffuser shroud with a broad-ring brim at the exit periphery, a rotor and a nacelle. We are now researching this type of wind turbine of large scale. When this type of wind turbine becomes large, we have to consider the wind load to the wind turbine. In order to decrease structure weight, Wind Lens has to be compact for flow direction. So, it has become difficult to keep high output of Wind Lens. Then, we have studied new model of Wind Lens which decrease the wind load and structure weight, and increase electrical power output.

Numerical Studies of Flows Around a Wind Turbine Equipped with Flanged-Diffuser Shroud by Using an Actuator-Disc Model

Unsteady 3-D direct numerical simulations based on the finite-difference method (FDM) are carried out for flow fields around a wind turbine equipped with a flanged diffuser shroud. Generally, it is difficult to simulate numerically the flow around rotational bodies like rotors of wind turbines, because of unsteadiness due to a moving body and complex geometry. Therefore, we have devised an actuator-disc model for a wind turbine for simulating the resistance and rotational forces on fluid. Introduced those volume forces devised from the actuator-disc model into the external terms in N-S equations, the unsteady flow around a wind turbine can be simulated. The results of numerical simulations are compared with the wind tunnel tests and show a good agreement for the velocity and pressure fields.

Development of a High-Performance Wind Turbine Equipped with a Brimmed Diffuser Shroud

We have developed a new wind turbine system that consists of a diffuser shroud with a broad-ring brim at the exit periphery and a wind turbine inside it. The brimmed-diffuser shroud plays the role of a device for collecting and accelerating the approaching wind. Emphasis is placed on positioning the brim at the exit of the diffuser shroud. Namely, the brim generates a very low-pressure region in the exit neighborhood of the diffuser by strong vortex formation and draws more mass flow to the wind turbine inside the diffuser shroud. To obtain a higher power output of the shrouded wind turbine, we have examined the optimal form for the brimmed diffuser, such as the diffuser open angle, brim height, hub ratio, centerbody length, inlet shroud shape and so on. As a result, a shrouded wind turbine equipped with a brimmed diffuser has been developed, and demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about five compared to a standard (bare) wind turbine.

Steady and Unsteady Flow Phenomena in a Channel Diffuser of a Centrifugal Compressor

The aim of this paper is to understand the time averaged pressure distributions and unsteady pressure patterns in a channel diffuser of a centrifugal compressor. Pressure distributions from the impeller exit to the channel diffuser exit are measured and discussed for various flow conditions. And unsteady pressure signals from six fast-response sensors in the channel diffuser are analyzed by decomposition method. The strong non-uniformity in the pressure distribution is obtained over the diffuser shroud wall caused by the impeller-diffuser interaction. As the flow rate increases, flow separation near the throat, due to large incidence angle, increases aerodynamic blockage and reduces the aerodynamic flow area downstream. Thus the minimum pressure location occurs downstream of the geometric throat, and it is named as the aerodynamic throat. And at choke condition, normal shock occurs downstream of this aerodynamic throat. The variation in the location of the aerodynamic throat is discussed