Wind Tunnel Test on the Breakthrough Laminar Aircraft Demonstrator Europe in the DNW-LLF

摘要

In the framework of the Clean Sky project BLAME (Breakthrough Laminar Aircraft Model wind tunnel testing in Europe) an A340-300 aircraft model was subjected to laminar flow testing in the 8m × 6m closed test section of the Large Low-speed Facility (DNW-LLF). A description of the main measurement techniques used to gather the required data for a laminar flow investigation is given. Statistical uncertainty in basic aerodynamic coefficients, attained with internal strain gauge balances, is discussed. The A340 model conies with an extensive data set covering more than 20 years of wind tunnel testing with different balances. The repeatability of balance data is discussed using uncertainty relations based on random error results in balance calibrations. A qualitative description of infrared thermography measurements, used to establish the transition location on the natural laminar flow (NLF) panel on the outer wing, is given as well. Not only is the applicability of this technique demonstrated, but also the capability of the DNW-LLF as a facility for laminar flow testing of full models with a large scale. Most extensively, the online optical position, attitude and deformation measurement technique is discussed. An optical, marker based tracking system using CCD cameras has been implemented to accomplish the online measurement of the wind tunnel model's full position, attitude and its deformation. In addition to the measurement of the aforementioned parameters the system also calculates online statistical error estimates of those parameters in excellent agreement with Monte Carlo type simulations.