There is a wide range of fixed-wing civil transport aircraft, varying from small training and recreational aircraft to large airliners. Numbers of passengers can range from less than 10 (business jets) to 100 (regionals) or over 500 (long-haul, high-capacity aircraft). Moreover, there is a considerable difference in range: from short distances to 12,000 miles or more for intercontinental flights.

 

Despite these striking differences, all aircraft manufacturers have to meet the same type of certification requirements with regard to acoustics and ice formation for example. Acoustic aspects include maximum noise levels as prescribed in national and international legislation. The noise sources of an aircraft can be divided into two categories: noise generated by the propulsion units or noise associated with the airframe itself, the latter playing an increasingly important role in aircraft design. As far as ice formation is concerned, manufacturers have to prove that their aircraft can maintain a sufficient level of performance and controllability under icy conditions.

 

Aside from these certification requirements, aircraft manufacturers are faced with an increasing focus on reduction of the use of fossil fuels during flights. In the light of this important environmental issue, there is a growing emphasis on optimizing the wing design.

 

DNW provides a variety of wind tunnels with sophisticated simulation and measurement testing techniques for all of the above-mentioned parameters. For instance, several of these facilities can achieve high Mach numbers to simulate the actual speed of an aircraft. Moreover, the ability to test at high Reynolds numbers in some of the wind tunnels ensures that the testing results closely approach full-scale values. DNW applies both intrusive and non-intrusive measurement techniques to gain an insight into the air flow around an aircraft and the resulting pressure, forces and moments. These tests provide information that is vital in perfecting the design of the wing, slats, flaps and the tail.

DNW’s measurement systems are among the best. Pressure distributions on aircraft models are measured with pressure scanning systems as well as by means of pressure-sensitive paint. Acoustic arrays are used to measure the precise location of noise sources. A complete series of balances is available for load measurements. We can also store and process large amounts of data. For example, when performing our state-of-the-art acoustic measurements we often use as many as 100 microphones, resulting in terabytes of test results.