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Synthetic Jet flow Control CFD and Characterization

Periodic Reporting for period 1 - SYNJET3C (Synthetic Jet flow Control CFD and Characterization)

Reporting period: 2017-10-01 to 2019-03-31

In aim at decreasing the consumption of the aircrafts, an idea is to limit the flow separation on the wings. Actually, the new Ultra high Bypass Ratio (UHBR) engines which are more ecologic engines tends to increase this separation effect. In this context, Active Flow Control (AFC) based on pulsed air blowing could be applied to engine-wing junction. Among this technology, the Synthetic Jet Actuators (SJA) are a solution without net mass flux. As the technology is now not well understood yet, SYNJET3C project aims at increase the knowledge of SJA in quiescent air condition and cross flow conditions.

In the current situation of climate change and environmental preoccupation, the reduction of aircraft consumption is an important question for society.

The first objective of SYNJET3C is to characterize an existing SJA designed by Fraunhofer ENAS and actuated by a piezo-membrane.
The understanding and modelling of the behavior of this SJA will allow to define the performance to reach with the next generation of SJA.
A new prototype will be designed, manufactured and tested.
"CFD computation in quiescent air conditions of the Fraunhofer SJA have been performed by ONERA. This calculation shows the output jet velocity and shape through the SJA nozzle.
The real geometry of the fluidic components (cavity + nozzle) is taken into account using the CAD model. The membrane displacement is applied as a periodic velocity inlet, instead of a moving mesh.
These results are published in the D1 deliverable ""Analysis of experimental results of SJA in quiescent air condition"" sent in 08/18. The numerical simulation identifies 5 important times during one cycle and the maximum outlet velocity appears for the phase pi/2+10°. The maximum velocity at the outlet is about 137m/s.

TRISITEC performed the experimental testing of SJA in quiescent air condition. These tests have been done using several fluidic configurations, characterized by variable height of the cavity and different sizes of the nozzle. The tested actuators are simplified actuators.
The measurements in terms of membrane displacement, output jet velocity and cavity pressure with a variable frequency of actuation are reported in the D2 deliverable ""Analysis of experimental results of SJA in quiescent air condition"" sent in 09/18. They show that the output jet velocity is very dependent on the dimensions of nozzle and cavity. The best tested configuration is the K1-D02 which gives an output jet velocity of 50m/s.

CTEC has built the system model of SJA in quiescent air conditions. It consists in a MATLAB model based on electro-mechanical approach and Helmholtz theory. The comparison of the model outputs with the TRISITEC measurements has shown the accuracy of the model to predict the behavior of the SJA in quiescent air condition. This is reported in D3 deliverable “Model of SJA in quiescent air condition.

In the first period of the project, the partners have contributed to increase the understanding of the SJA behavior in quiescent air condition via measurements and modelling. For the end of the project a similar work will be done in cross flow condition which is a real progress compared to the previous projects as ASPIC and VIPER. Then the design of a SJA with low mass will be a very interesting mechanism for the mass and consumption reduction of the aircrafts if the system reaches performance high enough in terms of output jet velocity and flowrate at the nozzle.

The success of the project could give to the European project partners an interesting place in the aircrafts market. Then, by an equal access of all European companies to this technology managed by CTEC, the impact for the European economy could be large.
Results of experimental testing of SJA in QAC, K3D05
CAD model of the SJA
Jet Velocity in QAC computed by CFD
System model outputs of SJA in QAC, K3D05