In the first phase of the project unsteady CFD simulations were made for the NGCTR to identify critical regions that could benefit from the use of ZNMF devices. As a result, 3 configurations were identified that could potentially benefit from the use of ZNMF devices: 1) a clean configuration, 2) a configuration with a deflected nacelle, and 3) a configuration with a downward deflected aileron. The targets to be reached through the use of ZNMF devices are a gain of 10% in maximum lift coefficient for configurations 1 and 2, and a gain of 10% in roll moment coefficient for configuration 3.
In the 2nd phase of the project a literature study was made on possible ZNMF devices, and the ASPIC synthetic jet actuator developed by Cedrat technologies was selected for the AFC4TR studies because it provides high exit velocities and high jet frequencies. This was followed by 2D CFD simulations for an airfoil with flap to study different parameters of the ZNMF device. These studies were extended to 3D studies (wing with flap). The conclusions of these studies were that to be effective, the ZNMF devices should be placed just upstream of the flow separation, that a high blowing velocity should be favored, and that the jet frequency should be around 50-100 Hz.
Based on these results unsteady CFD simulations were made for the 3 configurations of the NGCTR with ZNMF devices, using a jet velocity of 300 m/s and a jet frequency of 65 Hz. In these initial CFD simulations 3 pairs of ZNMF devices were placed on the wing for configurations 1 and 2, or on the aileron for configuration 3. Results of these initial CFD simulations showed that the ZNMF devices had an influence on the flow, but that their locations need to be optimized.
For NGCTR configuration 1 a total of 11 unsteady CFD simulations were made using different numbers of ZNMF devices (ranging from 6 to 20), placed at different locations. From the results obtained it was concluded that using ZNMF devices on this configuration will not lead to aerodynamic benefits.
For NGCTR configuration 2 the main focus was on the case with 12o angle of attack. For this configuration 9 unsteady CFD simulations were made using 6 to 20 ZNMF devices at different locations on the wing. For this configuration the ZNMF devices permitted to reduce the massive flow separation on the wing, and a gain in lift of 5.67% was obtained compared to the case without ZNMF devices. However, for this configuration there remain open questions concerning the optimal location of the ZNMF devices, and the influence of the grid on the results. One additional unsteady calculation with ZNMF devices was made for the configuration with 8o angle of attack. At this angle of attack the flow separation in the middle of the wing is reduced in size, and as a result the ZNMF devices have only a small influence.
For NGCTR configuration 3 seven unsteady CFD simulations were made using 3 pairs of ZNMF devices at different locations in the chordwise direction on the aileron. When placing the ZNMF devices just upstream of the flow separation it was possible to increase the roll-moment of the aircraft by 3.3%.
The results of the AFC4TR project were widely disseminated:
• 2 news letters were published
• Several announcements on LinkedIn and researchgate.com
• 11 papers or presentations were given at conferences and workshops during the project, and these papers or presentations were made publicly available
• 1 paper was given at a conference after the project (January 2023)
• 1 paper has been accepted with minor modifications for a peer reviewed journal
• 2 papers will be submitted to peer reviewed journals in 2023
Finally, the results of the AFC4TR project will be exploited by the project partners in future national or EU funded projects.
