The STARLET project objective was to design a new concept of active flow control system based on suction-blowing devices for the control of the aerodynamic load on aircraft wing and to check its usability by CFD calculations and wind tunnel tests. The aim of the flow control concept to be investigated was the alleviation of wing structural loading, especially of the bending moment, having direct influence on the structure fatigue life, through the modification of wing aerodynamic load distribution in gusts and off-design flight conditions. To achieve this goal the implementation of suction-blowing technique for active control of aerodynamic load distribution on aircraft wing was proposed.
Several concepts of active flow control system were proposed and evaluated using CFD calculations and the most promising solutions of suction-blowing systems were investigated through wind tunnel tests. These experimental tests included fully-3D investigations on a large-scale wing model (semi-span wing). It was expected, that as a result of these investigations, innovative, dedicated solutions of suction-blowing "smart structures" were designed and adapted in wing-load-control systems. The proposed work began with a review of the existing state of knowledge on the topics of the project, leading to the formulation of requirements for the concept of active load control. It was assumed that the ILOT concept was directed towards blowing devices located in selected regions of the wing including spoiler area and vicinity of the trailing edge. For the wind-tunnel investigation an 2.4 m, existing semi-span wing model equipped with movable aileron and flap was proposed to be used. The model of wing was prepared for balance measurements on the 5-component wall balance. The model also enabled the estimation of spanwise load distribution. To achieve the goals of the project a special policy of project monitoring and reduction of the potential risk was adopted.
The STARLET project "Basic wind tunnel investigation to explore the use of Active Flow Control technology for aerodynamic load control" was realised by Institute of Aviation, Warsaw, Poland, based on Clean Sky call for proposals no. JTI-CS-2011-01-SFWA-01-037.
The duration of the project was 36 months, budget was 250 000 EURO with Clean Sky JU financing 75% of the costs. The main requirements of the Call for Proposal were to investigate the capabilities of flow control solutions, developed in the past for active load control, particularly for reduction of high off-design aerodynamic loads. It was envisaged that modifications of the past solutions would be necessary to adapt them for this particular purpose. Two locations on the wing chord were indicated for the flow control devices: the first one in the region where traditional spoiler is located and the second one in the vicinity of the trailing edge.
The project goal was to investigate the effectiveness of the proposed by the applicant fluidic load control concept in low-speed wind tunnel investigations as well as in numerical flow control simulations. It was suggested also that a wing model with sweep would be beneficial for the investigations. The Institute of Aviation proposed conducting the investigations in the 5m-diameter low speed wind tunnel on a 2.4m half-span wing model with flow control devices located as recommended by the Topic manager. The project included literature study of the load control capabilities of the existing flow control solutions, design of the flow control devices to be implemented on the wing model, numerical flow simulations of the flow control concepts, fabrication of the flow control system and modification of the model and, finally, wind tunnel investigations and analysis of the results.