Measurement of quality test of aerodynamic profiles in wind turbine blades using laser triangulation technique

Abstract

The development of an optical contact instrument for measuring the geometric shape of aerodynamic profiles on blades of small power wind turbines is presented. The instrument uses the triangulation principle, where a structured line laser pattern is projected onto the surface of one of the faces of the blade under test, a camera captures the image of the line and is processed to interpret the distorted form of the projected line. A linear sweep of the instrument makes it possible to measure the profile in another section of the blade. Comparison and evaluation results of two symmetric profiles of the NACA 0012 family are presented, one manufactured in a 3D printer and the other one is a metal profile AF104 of a subsonic wind tunnel. Additionally, three sections of a blade with profile FX 63‐137 of a 1.5 kW wind turbine were evaluated. An aerodynamic analysis shows a reduction in the lift coefficient and in the efficiency of the aerodynamic profile, as well as an increase in the drag coefficient. The sensitivity of the instrument is 0.1 mm on the Z‐axis.

Vibration Measurement Using Laser Triangulation for Applications in Wind Turbine Blades

“…If a disturbance is applied to the beam, it begins to vibrate in the direction of the axis of the reference system, and these mechanical displacements are observed in the Figure 1 as lateral displacements ∆ . A mathematical expression associates the changes of height ∆ with the observed lateral displacements ∆ ′, knowing in advance the parameters such as the distance from the image plane to the pinhole , the distance from the pinhole to the plane of the beam , and the angle of camera observation , as in reference [22] we have…”

“…Experimentally, measuring the parameters involved in Equation ( 10) is not very practical, so the use of a calibration process of the optical measurement system is conveniently used, i.e., the motorized linear displacement stage travels known equidistant displacements along the z axis, and these displacements are observed in the image plane (Figure A mathematical expression associates the changes of height ∆z with the observed lateral displacements ∆x , knowing in advance the parameters such as the distance from the image plane to the pinhole k, the distance from the pinhole to the plane of the beam r, and the angle of camera observation α, as in reference [22] we have…”

“…Height changes in the reconstruction of a profile are measured from the lateral displacements of the light projected on the object under test, and generally the projection has a linear structure, which is achieved by refraction in a cylindrical lens. Furthermore, LTT have a simple arrangement and fast measurement speed, so there exists a wide range of applications in the inspection and quality control of the production process [22][23][24][25][26][27][28][29]. An interesting contribution of this technique is shown in reference [22], where the use of LTT in the reconstruction of aerodynamic profiles for quality tests on wind turbine blades is presented.…”

“…Furthermore, LTT have a simple arrangement and fast measurement speed, so there exists a wide range of applications in the inspection and quality control of the production process [22][23][24][25][26][27][28][29]. An interesting contribution of this technique is shown in reference [22], where the use of LTT in the reconstruction of aerodynamic profiles for quality tests on wind turbine blades is presented.…”

Optical Setup for Error Compensation in a Laser Triangulation System

“…It is a commonly used method in industrial applications due to its simple, cheap, and robust operation and high measurement rates [ 10 ]. Disadvantages include the decreasing resolution with increasing measurement distance and its strong dependency on the pointing stability of the laser source as well as the surface properties of the measurement object [ 11 , 12 ]. Most commercialized triangulation systems typically have a relative precision of around to at a working distance of 20–1000 with a measurement range of to [ 13 ], though there are a few systems available with a measurement range of up to several meters [ 2 ].…”