Full-Field Displacement Measurements of Helicopter Rotor Blades Using Stereophotogrammetry

Chenglin Zuo,Chunhua Wei,Jun Ma,Tingrui Yue,Lei Liu,Zheyu Shi,Ennes Sarradj

doi:10.1155/2021/8811601

Chenglin Zuo, Chunhua Wei + Show 5 more

Open Access

https://doi.org/10.1155/2021/8811601

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Abstract

This study presents a stereophotogrammetry approach to achieve full-field displacement measurements of helicopter rotor blades. The method is demonstrated in the wind tunnel test of a 2 m diameter rotor, conducted at the 5.5 m × 4 m Aeroacoustic Wind Tunnel of China Aerodynamics Research and Development Center (CARDC). By arranging the retroreflective targets on the special hat installed directly above the rotor hub, the dynamic motion of the rotor shaft was tracked accurately, and a unified coordinate system was established on the rotor. Therefore, three-dimensional coordinates of instantaneously measured targets attached on the blade could be transformed to the unified rotor coordinate system, thereby providing a basis for consistently calculating the blade displacements at different test conditions. Moreover, location deviations of the blade caused by the vibration of the measuring system or the rotor due to freestream and rotor rotation were also effectively corrected through coordinate transformation. Comparisons of experimental and simulation results for a range of hover and forward flight conditions show good magnitude and trend agreements.

Highlights

Rotor is the crucial component of the helicopter, which is directly related to flight safety and flight quality
Quite few studies considered the vibration effect. We address these issues and propose a stereophotogrammetry approach for the rotor wind tunnel test, which can make effective vibration correction and realize the full-field displacement measurements of rotor blades at arbitrary flight conditions
3D coordinates of instantaneously measured targets on the blade could be transformed from the camera coordinate system to the rotor coordinate system, which provides a basis for more accurately estimating and comparing the location of the blade displacement relative to the rotor shaft at different

Summary

Introduction

Rotor is the crucial component of the helicopter, which is directly related to flight safety and flight quality. At the NFAC 40- by 80-Foot Wind Tunnel, Straub et al [7] introduced the stereophotogrammetry to achieve the displacement measurements of a full-scale rotor blade in quadrant one of its rotation range during a forward flight condition. Olson et al [8] performed blade displacement measurements in quadrants one and two with fourcamera stereophotogrammetry during the full-scale wind tunnel testing of the UH-60A Airloads rotor. This test was further improved with eight cameras to achieve. We address these issues and propose a stereophotogrammetry approach for the rotor wind tunnel test, which can make effective vibration correction and realize the full-field displacement measurements of rotor blades at arbitrary flight conditions. The main purpose is to obtain a detailed understanding of the rotor’s dynamic behavior and provide accurate data for structural design and aerodynamic analysis of the helicopter rotor system

Experimental Setup

Binocular Stereophotogrammetry

Experimental results CSD results

Results and Discussion

Experimental results

Conclusions