The rapid progress of light emitting diode (LED) technology has recently resulted in the availability of high power
devices with unprecedented light emission intensities comparable to those of visible laser light sources. On this basis two
versatile devices have been developed, constructed and tested.
The first one is a high-power, single-LED illuminator equipped with exchangeable projection lenses providing
a homogenous light spot of defined diameter. The second device is a multi-LED illuminator array consisting of a number
of high-power LEDs, each integrated with a separate collimating lens. These devices can emit R, G, CG, B, UV or white
light and can be operated in pulsed or continuous wave (CW) mode. Using an external trigger signal they can be easily
synchronized with cameras or other devices. The mode of operation and all parameters can be controlled by software.
Various experiments have shown that these devices have become a versatile and competitive alternative to laser and
xenon lamp based light sources.
The principle, design, achieved performances and application examples are given in this paper.
The non-intrusive in-flight deformation measurement and the resulting local pitch of an aircraft propeller or helicopter rotor blade is a demanding task. The idea of an imaging system integrated and rotating with the air-craft propeller has already been presented at the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been designed, constructed and tested in the laboratory as well as in-flight on the Cobra VUT100 of Evektor Aerotechnik, Kunovice (CZ). The major aim of the EU FP7 project AIM2 ("Advanced In-flight Measurement techniques 2" – contract No. 266107) was to ascertain the feasibility of this technique under extreme conditions - vibration and large centrifugal forces – to real flight testing. Based on the gained experience a new rotating system for the application on helicopter rotors has recently been constructed and tested on the whirl tower of Airbus Helicopters, Donauwoerth (D). In this paper the principle of the applied Image Pattern Correlation Technique (IPCT), a specialized type of Digital Image Correlation (DIC), is outlined and the construction of both rotating 3D image acquisition systems dedicated to the in-flight deformation measurement of the aircraft propeller and helicopter rotor are described. Furthermore, the results of the ground and in-flight tests of these systems will be shown and discussed. The obtained results will be helpful for manufacturers in the design of their future aircrafts.
KEYWORDS: Cameras, Imaging systems, Digital image correlation, Stereoscopic cameras, Sensors, Camera shutters, Calibration, Global Positioning System, Digital imaging, 3D metrology
The non-intrusive in-flight measurement of the deformation and pitch of the aircraft propeller is a demanding task. The idea of an imaging system integrated and rotating with the aircraft propeller has been presented on the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been constructed and tested in the laboratory as well as on the real aircraft. In this paper we outline the principle of Image Pattern Correlation Technique (IPCT) based on Digital Image Correlation (DIC) and describe the construction of a dedicated autarkic 3D camera system placed on the investigated propeller and rotating at its full speed. Furthermore, the results of the first ground and in-flight tests are shown and discussed. This development has been found by the European Commission within the 7th frame project AIM2 (contract no. 266107).
A combination of high-speed stroboscopic imaging with the Image Pattern Correlation Technique (IPCT) enables for
non-intrusive measurement of surface deformation of fast vibrating or rotating objects. In this paper the dedicated
instrumentation for the measurement of the deformation of aircraft propellers as well as first results of its application will
be described.
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