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ENODISE is designed as a low-to-mid-TRL enabler project, meant to develop the knowledge, data, tools and methods that are necessary to understand, model and optimize engine-airframe aerodynamic and acoustic installation effects, with a strong focus on innovative architectures bringing a tighter integration of the propulsive system with the wing, fuselage or control surfaces. The project is proposing activities at TRL levels between 2 and 4 in order to build a solid knowledge base and methods to be exploited in ongoing and future higher-TRL projects. Simplified geometrical configurations will be investigated here, being the only approach permitting to unravel the intricate aeroacoustic mechanisms involved in future aircraft architectures, and eventually enable their reliable simulation and optimization while mitigating the adverse effects.

A tighter integration of the propulsion system into the airframe brings both beneficial and detrimental effects. On the positive side, ingesting the airframe boundary layer should in principle improve the overall performance of the aircraft. Furthermore, one expects that placing the propulsion system closer to the airframe should bring interesting acoustic shielding effects, especially if the distance to the airframe can be made small enough compared to the airframe dimensions, leading ultimately to the partly-buried engine concept. The adverse effects include noise source reinforcement due to the unsteady loads that result from potential distortion or wake / boundary layer viscous effects. The problem is quite complex as the propeller interacts simultaneously with a disturbed potential flow and with the turbulent boundary layer, bringing multiple flow scales into play. The maximization of the efficiency of the integrated airframe-propulsion system, while minimizing noise production, rests on the postulate that at least one local minimum does exist.

As of today, and to the consortium’s knowledge, the presumed existence of such an optimum integration for a given concept was never demonstrated by means of systematic experiments or numerical simulations. We are thus lacking a quantitative knowledge about the potential benefits and downsides of candidate integration strategies. But more crucially, we are lacking tools having demonstrated without ambiguity their capability to predict this optimum. The first objective of ENODISE is the development of a novel research approach, based on extensive parametric test campaigns complemented with numerical simulations, permitting to understand and quantify the favourable and adverse aerodynamic and aeroacoustic installation effects in novel propulsion integration concepts. The possibility of local or global optima will be investigated on well-controlled generic and representative configurations. The gains and losses in terms of noise and propulsive efficiency will be quantified and correlated with the flow properties, while developing a methodology for up-scaling the results towards more realistic configurations.

The next question is whether the design guidelines and procedures currently in use for propulsive systems, which often assume ‘clean’ inflow/outflow conditions, are adequate for installed conditions with distorted inflow/outflow. Design alterations are most likely needed to yield optimal performance and minimum noise when the engine is placed upstream or downstream of a wing or pylon, or is partly buried within the airframe. The background knowledge about the nature and extent of those modifications is however very limited. The second objective of this project is thus to perform numerical optimization studies in clean vs. installed conditions to generate this background knowledge, and to validate the results quantitatively through experimental verification.

Then, the consortium realizes that a tighter integration of the propulsion system with the airframe offers opportunities to explore novel flow and acoustic control strategies. One can easily imagine that, if successful, those advanced noise mitigation strategies could open the possibilities of significantly improving further the optimum design, which loops back to the above points. The third objective of this project is the inclusion of innovative flow and acoustic control technologies in the optimization loop in order to design better integrated aircraft with minimal detrimental or favourable installation effects. Again, the benefits in terms of noise emission, propulsive efficiency and associated gaseous emissions will be quantified and tentatively extrapolated towards the full-scale layout.

In contrast with previous projects, the ambition of ENODISE is to analyse configurations that will be geometrically simple and for a broad range of dimensional and operational parameters such as the relative position the propulsor with the airframe, the ingested flow quality, the propulsor design itself, etc. This will result in a vast amount of data permitting to test novel experimental techniques, modelling approaches, optimization algorithms and mitigation strategies. The last, and certainly not least, objective of the project is the constitution of extensive, well documented and cross-validated experimental and numerical databases that will be made publicly available for benchmarking purposes. The exploitation of those data will be enhanced by the definition of non-proprietary geometries, compatible with the capabilities of a majority of experimental facilities and simulation frameworks thanks to their small scale and geometrical simplicity. Nevertheless, the enormous size of the resulting database will raise specific challenges and require specific developments in terms of data management including archival, mining and curation.


von Karman Institute for Fluid Dynamics


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