Tania Kirmse

Optical In-Flight Wing Deformation Measurements with the Image Pattern Correlation Technique

This chapter addresses image based deformation measurements and the development of specific optical deformation metrology for experimental flight test installations. Apart from the technical background it is a contribution to the national funded research projects FTEG-InnoLA and HINVA (LuFo IV). Based on a standard setup the measurement equipment required to perform the Image Pattern Correlation Technique (IPCT) was adapted to an application on an ultralight aircraft. In order to design the test setup a digital camera mock-up (camera DMU) was used. The analysis of selected flight test data proved the capability of the miniaturized IPCT system. A second flight test setup was developed for the DLR research aircraft Airbus A320 “ATRA” using the experience gained from the ultralight measurements. Here, the design of the IPCT components also made use of the camera DMU. Both the overall wing deformation and that of high lift devices have been measured in high-lift configuration.

Recent developments of image based measurement methods for application to transonic flows in industrial wind tunnels

Abstract The experimental investigation of unsteady complex flow fields in wind tunnels requires advanced measurement techniques. The most important of such image based measurement techniques are those for the measurement of planar flow velocity fields, planar pressure distribution, model location and deformation, model temperature and quantitative high speed flow visualization. The applications as carried out by DLR range from low speed flows to transonic flows, from high lift configurations to propellers and rotors, from wake vortex investigations in catapult facilities and water towing tanks to investigations of vortex break down phenomena on delta wings. The capability to use image based measurement techniques in transonic flows requires dedicated technical developments and experienced scientists due to the special environment of a transonic wind tunnel. In this paper an overview of the state-of-the art of the application of image based measurement techniques in transonic flows as performed by DLRs Institute of Aerodynamics and Flow Technology will be given.

Modelling and Validation of a V2500 Honeycomb-Core Fan Blade

Structural mechanics and also aerodynamics and aero elastics have a need for detailed and exact models of the regarded structures to create reliable results. The Institute of Structures and Design of the German Aerospace Center (DLR) located in Stuttgart has considerable experience in the field of mechanical analysis, design and assessment of aero engine structures as well as in the processing of these structures for further applications in aerodynamics and aero elastics. It is important to ensure that the hereby used methods in modelling and simulation are producing authentic results and the created data is feasible for usage in the linked disciplines. Therefore, the simulated behavior of a fan blade model of the engine of DLR research aircraft A320-ATRA (Advanced Technology Research Aircraft) was validated with measurements of real fan blades during the SAMURAI project. The paper describes a modelling technique for a fan blade with titanium honeycomb core in its context of an IAE V2500 aero engine based on provided CAD-data, x-ray and CT scans and measurements on existing structures. The fan blade model and particularly the influence of the honeycomb core were validated against Eigen frequencies and masses of real blades. With this baseline, simulations for several loading cases respectively several operating points were performed. The gained results were used on the one hand for aerodynamics and engine performance calculations in the context of the project and on the other hand for comparison with fan blade deformations which were determined by IPCT-measurements (Image Pattern Correlation Technique) on the real engine in operation.

Simultaneous Measurements of Unsteady Aerodynamic Loads, Flow Velocity Fields, Position and Wing Deformations of MAVs in Plunging Motion

A new wind tunnel environment for low Reynolds number testing of Micro Air Vehicles (MAV) is introduced, providing a test rig for plunge and pitch motions and a 6-component force balance. In this study a rigid as well as a flexible version of a typical MAV wing is investigated. Optical measurements techniques are adapted to measure simultaneously the instantaneous model position, orientation, wing deformations and flow fields.

Image Based Fan Blade Deformation Measurements on an Airbus A320 V2500 Engine in Ground Operation

The Image Pattern Correlation Technique (IPCT) was applied to measure the fan blade deformation of the IAE V2527 engine operating at Maximum Continous Thrust (MCT). The ground test on the DLR research aircraft A320-ATRA was a main part of the DLR project SAMURAI which wanted to use the ‘Synergy of Advanced Measurement Techniques for Unsteady and High Reynolds Number Aerodynamic Investigations’. The stereo camera system was fixed in front of the left engine. For certification reasons the correlation pattern had to be projected to the fan by a laser. The IPCT evaluation were improved to cope with the special challenges of the measurement and to enable a comparison with Computational Structural Mechanics (CSM) results finally.

The Application of Background Oriented Schlieren Method to Aircraft Wake Vortex Investigations

Vortex wakes of conventional aircraft and their propagating nature close to the ground have a great impact on the safety and efficiency of the traffic flow on an airport. The development of a measurement technique which helps detecting e.g. the density gradients in the air due to the wake vortices and understanding the nature of such a flow structure in its natural environment can improve the predictability of this hazardous phenomenon. Therefore, the practical aspects of the implementation of an advanced Schlieren technique on an airport are described in this chapter. Two experiments based on slightly different setups and locations relatively to the runway were conducted in order to assess the feasibility of the Background Oriented Schlieren method (BOS) for the detection and investigation of aircraft wake vortices. The evaluation of the obtained data indicated a sufficient ability of this technique to detect strong density gradient but on the other hand, turned out to be less efficient when dealing with the peculiarities of a large scale outdoor experiment.

Fan Blade Deformation Measurements on the DLR Airbus A320-ATRA by Means of IPCT as Part of the Ground Test Campaign in the Frame of the DLR-project SAMURAI

The Image Pattern Correlation Technique (IPCT) was applied to measure the fan blade deformation of the IAE V2527 engine operating at Maximum Continous Thrust (MCT). The ground test on the DLR research aircraft A320-ATRA was a main part of the DLR project SAMURAI which wanted to use the ‘Synergy of Advanced Measurement Techniques for Unsteady and High Reynolds Number Aerodynamic Investigations’. The stereo camera system was fixed in front of the left engine. For certification reasons the correlation pattern had to be projected to the fan by a laser. The IPCT evaluation were improved to cope with the special challenges of the measurement and to enable a comparison with Computational Structural Mechanics (CSM) results finally.