Hikaru Matsumiya

Three Dimensional Navier-Stokes Flow-Field Computations through Horizontal Axis Wind Turbine Blade

This paper presents the three-dimensional (3D) flow analysis around a horizontal axis wind turbine using pseudo-compressibility method combined with overset grid method. The computational results of 3D Navier-Stokes solution agree with two-dimensional (2D) ones of corresponding relative angle of attack at the middle span. However, it is found that the angle of attack at near the tip region is predicted to be smaller than that derived with 2D simulation which neglects the effect of tip vortex. The data obtained with the proposed algorithm of Computational Fluid Dynamics (CFD) are compared with the Blade Element and Momentum theory (BEM) data for a given angle of attack at each span section. Both sets of data are in good agreement with each other at the middle span position. Both BEM and CFD are able to analyze the down wash effect induced by a tip vortex and other variance of bound vortex in the span wise direction. However, the BEM underestimates the angle of attack at the hub and tip side where 3D flow effects are strong. In other words, the BEM estimates larger induced velocity than CFD.

Prospect of offshore wind energy development in Japan

In Japan, the cumulative capacity of wind turbine generation systems on land has increased steadily in recent years. To install a large number of wind turbines has inherent problems such as shortage of suitable land, and inadequate infrastructure such as power cables and roads. The necessity for development of offshore wind turbine generation systems has been recognised based on the above backgrounds. An expert committee to survey the prospect of offshore wind turbine generation in Japan was organised last year. In this paper, the prospect of offshore wind energy development in Japan is reported based on the discussion in the committee. As a result, it was found that there are some undesirable circumstances for offshore wind energy utilisation in Japan. For that reason, we need technological innovation as well as an increase in scale of wind farms in order to achieve an economical profit. The difficulty in realising of offshore wind farms in Japan relates to Japanese inshore conditions, various legal regulations and fishing rights issues.

Field Operation and Track Tests of 1-kW Small Wind Turbine Under High Wind Conditions

A 1-kW small horizontal-axis wind turbine “Airdolphin,” capable of high wind operation up to 50 m/s without pitch control system, is now under global round robin tests. The present paper reports a series of technical approach including design/analysis, track tests, and field tests conducted in support to the design process. One windy site “Erimo” and one offshore site “Fukushima” were chosen. For example, at “Erimo,” a record of one-day generation was 8.831 kWh on November 13, 2006 (day-averaged wind speed; 11.8 m/s) with 36.8% of capacity factor. An operation data under an attack of typhoon with 50 m/s maximum wind speed demonstrated the technical concepts of high wind operation and safety. A new term “capatureability” as an indicator of WT performance was proposed.