Test set-up: A number of quantities can be measured during the simulated bird strikes
“The test set-up in the laboratory is quite simple”, explains Frederik Allaeys, who is responsible for performing the tests. “The bullet-shaped bird is loaded into a tube and shot out at a pressure of some 30 to 40 bar, which gives it a speed of 200 to 250 metres a second. At the end of the tube is a metal chamber containing the part to be tested. This could be complete components, fan blades or plates made from new types of material. There is underpressure in the chamber in order to reduce air resistance, and the effects of the pressure wave on the measurement. Before entering the chamber the bird passes through a stripper that removes the sheath from the block of gelatine.” A number of quantities can be measured during the simulated bird strikes: the bird’s speed and acceleration, the pressure, displacement, vibration and impact of the strike, and possibly the amount of stretch and deformation of the materials. The entire test is recorded on video. Preparing a test takes about a day and the average cost of each one is some 1500 euros. Each test is performed twice to validate the results. It is very important for the progress of a test to be recorded and analysed accurately, which is difficult to do for an event that lasts only about two seconds. To do this the university needed a data acquisition system that could not only collect and process data from multiple measurement channels simultaneously, but could do so at very high speeds. The trigger in such tests is crucially important in starting all recording simultaneously and on time.