For active load alleviation, extensive CFD computations were performed to characterise, separately, the aileron and the spoiler of the FTB2 configuration. A variable fidelity approach was used to enrich the CFD database. CFD results were obtained at both wind-tunnel and full-scale Reynolds numbers. These results were then used with wind-tunnel data from the one atmosphere RUAG facility in a data fusion approach, to obtain corrected data at full-scale Reynolds number. In this variable fidelity approach, the CFD data was classed as the lower-fidelity data, which described the Reynolds number dependence of the aerodynamics. The higher-fidelity wind-tunnel data then provided a correction to the CFD data. The results for aileron aerodynamics showed a clear Reynolds number dependence for roll increment, with control power increasing as Reynolds number increases, whereas for all spoiler deflections only a weak dependence on Reynolds number is indicated.
The output from the active load alleviation work has been exploited in two main ways. Firstly, the processes developed and the knowledge accrued in ReLOAD have allowed ARA to successfully bid for other Clean Sky 2 projects. Secondly, ARA has been able to enhance its commercial offering to its customer base. The Company is actively promoting a more integrated approach between its CFD and wind-tunnel businesses and the Reynolds number extrapolation work done in ReLOAD is entirely consistent with this.
The capability to use the spoiler as a passive loads alleviation device was investigated in the first part of the ReLOAD project. The fully passive spoiler results showed that it was possible to alleviate the loads, however, the spoiler did not close automatically after gust encounter. Therefore, the spoiler needed to be closed actively rendering the spoiler semi-active rather than fully passive and this was investigated. A new aerodynamic methodology was developed for the spoiler, as well as for the aileron, which made use of high-fidelity Navier Stokes CFD loads. The newly developed aerodynamic methodology was validated and successfully applied to aeroelastic simulations of a free-flying flexible aircraft model. It was demonstrated that the aileron is more efficient as compared to the spoiler when it comes to active loads alleviation.
The loads alleviation potential of a flexible winglet was also investigated using a parametric study. Parameters investigated were the shear centre location, the winglet weight, and the winglet flexibility. The parametric winglet was exposed to a series of vertical gusts, and it was shown that the loads at the root of the wing were alleviated to a limited extent only. Designing the winglet for minimum weight resulted in an increase in wing root bending moment. A novel measure was derived through minimising the frequency of a mode coupling wing and winglet bending. A 30% lighter winglet could be designed using this approach.
The ReLOAD research was exploited in other Clean Sky 2 projects. There, the ReLOAD methodology is refined and used for the design of the next generation movables to be applied to commercial and business jet aircraft. Furthermore, the ReLOAD project resulted partially in the initialization of a TUD internal project called SmartX which also involves the European aeronautical industry.
The ReLOAD results were disseminated in four international conferences related to smart structures and aeroelasticity. The work was also disseminated in academia at workshops for TU Delft specifically and for all technical universities in the Netherlands. Finally, the work was disseminated in industry during an Airbus PhD day.
