IMAGE aims to reinforce the collaboration with China in the field to be addressed, which exploits the achievements of a set of subsequent Coordination and Support Action (CSA) projects AEROCHINA, AEROCHINA2, GRAIN and GRAIN2 (ongoing), fostering cooperation between industries, academia and research organizations in the aeronautical sectors of Europe and China. AEROCHINA and AEROCHINA2 have led to the birth of two EU-China collaborative research projects in FP7, MARS and COLTS, focusing respectively on drag reduction and Titanium alloy casting. In addition, using the platform of the CSA network projects, European and Chinese research organizations, universities and industries have also made effort to formulate two proposals in FP7, NEXTEP and NORTH2050, addressing aircraft noise-control technologies. Both proposals were highly scored in the evaluation, not funded though. The IMAGE project not only takes the criticism of these previous proposals into account, but also targets the latest aeroacoustic topics of mutual interest. It is worth noting that a number of partners who collaborated in the MARS project are now also in the IMAGE consortium, which will certainly represent a great benefit in terms of communication and interaction.
The flourishing of civil aviation industry in China over the recent years has been supported by research activities. Aeroacoustics and flow control in particular, have received a significantly increasing attention from a number of large Chinese research institutes, of which the most prestigious and active are gathered in the IMAGE consortium. The major national research programs on aeroacoustics in China are organized by ASRI (one of the coordinators). In one of its projects, ‘External Noise Prediction, Analysis and Test’, a semi-empirical code to predict aircraft noise has been developed for the prediction of community noise during aircraft take-off, cruise and landing, with a particular focus on the engine contribution. Using this code, the near field noise of the ARJ21-700 aircraft has been predicted. Such semi-empirical tools, once tuned and validated by dedicated microphone array measurements, are very powerful to compare the impacts of different operating procedures. In fact, similar semi-empirical prediction methods and acoustic array measurement techniques are also being investigated in Europe, and the cooperative framework put in place in IMAGE will be quite instrumental to grow these research areas in Europe and China altogether. NPU has also placed its attention on microphone array techniques to identify aircraft noise sources in one of its facilities (Figure 1.4). In that field, the Gas Turbine Group from NPU has successfully developed new data processing techniques for microphone arrays. Research aimed at similar goals has been performed in Europe (e.g. at DLR and ONERA).
Research efforts are also being conducted in Europe and China to elaborate sophisticated numerical techniques. For example, Computational Fluid Dynamics (CFD) and Computational Aero-Acoustics (CAA) methods are being developed by European and Chinese partners of the present consortium for the evaluation of rotor/stator interaction tone noise production and propagation in turbomachinery. Modelling approaches relevant to airframe and fan noise are being investigated in Europe and China, in many cases, with intensive collaboration between individual IMAGE partners (for example, BUAA, THU and CFDB, THU and Chalmers, BUAA and KTH, to just mention a few) on topics such as high-order CAA and CFD methods in different levels.
Of these China-EU organization-to-organization collaborations, one of the typical examples is THU, who participated in the EU FP7 project, ATAAC (2009-2013), where Chalmers, CFDB, ONERA, NLR and NUMECA were also partners. In this ATAAC project, several fundamental (step stones) and application-challenging flow configurations have been investigated, mainly using advanced hybrid RANS-LES computations. Among others, flows over/around single airfoil with buffeting phenomena, tandem cylinders, high-lift three-element configuration and rudimentary landing gear were successfully computed. The collaboration has been proved very fruitful.
In the EU-China collaborative project MARS, targeting flow separation control for drag reduction, plasma actuation has been studied experimentally and numerically by a number of European and Chinese partners. From a flow-control point of view though, this would nevertheless provide very useful implications for noise control using plasma actuators. Many partners of the EU-China collaborative project, MARS, are also in the IMAGE consortium, the IMAGE project will certainly benefit from the experience gained and lessons learned. This will surely reinforce a much improved collaboration to achieve the best project progress.
The previous EU-China collaborative work at EU level has proved to be a powerful engine driving the research achievements of mutual interest, and even facilitating mutual understandings. This is particularly true in studies on emerging concepts and technologies, by sharing the load of man power and research resources to achieve the best project outcome.
In China, the study of flow control, particularly in the area of plasma actuation, has made remarkable progress, for which ASRI is one of the leading players using their anechoic wind tunnel. The groups at ASRI and ARI have conducted studies of dielectric barrier discharge (DBD) actuators, taking into account both aerodynamic and acoustic aspects. The method has already been demonstrated for reducing the tonal noise from a cavity by producing span-wise velocity variation in the shear layer. ARI was a partner in the EU-China project MARS, responsible for experimental measurements of flow control of airfoil flow using plasma-DBD actuators in their wind-tunnel facilities.