Experimental Study on Flow around Blades of Horizontal Axis Wind Turbine in Wind Tunnel (2nd Report, Studies on the Flow around Blade Based on Pressure Distribution)

Abstract

This paper describes the results of the surface pressure measurements on a wind turbine rotor and the velocity measurements around the rotating blade. The experiments are carried out in a wind tunnel with a 2.4 m diameter three-bladed wind turbine. The pressure taps are set at 31 positions in each of four test sections. Four radial sections at γ/R=0.3, 0.5, 0.7 and 0.85 are selected for the measurements. The pressure distributions are measured for both rotating and non-rotating situation. These pressure distributions are compared and used for detecting the angle of attack for the rotating blade. The pressure distribution at γ/R>0.7 shows the good agreements between rotating and non-rotating situation. The pressure distribution for the inner part of γ/R<0.5 shows the stall delay.Also, by using the angle of attack estimated from the pressure distribution and the velocity distribution, the representative point for the relative velocity to the blade section is discussed. The angle of attack is compared with the designed value by the blade elements momentum theory.