Flap Gap Oscillatory Blowing on 2D and 2.5D Wing

Abstract

Here we present preliminary results obtained in developing an active flow control system for high lift systems at advanced TRL level. The work is based on theoretical and experimental work performed in AVERT EU FP6 project where the oscillatory flap gap blowing system was designed and tested on a INCAS F15 2D wing model. Pressure data and global loads have been recorded for a complex evaluation of the basic flow control mechanism. In 2.5D test cases this work has been extended so that the proposed system may be selected as a mature technology in the JTI Clean Sky, Smart Fixed Wing Aircraft ITD. For this goal, new experimental setup was used and also updated electronics for the blowing system have been introduces. This was complemented by a new extension for the data acquisition system and visualization tools. Finally global correlations for basic lift increments have been compared with the reference 2D case and analysed with respect to the system efficiency. INTRODUCTION The overall objective of AVERT Project is to deliver upstream aerodynamics research that will enable breakthrough technology development and innovative aircraft configuration development leading to a step change in aircraft performance. The project objective is to be achieved through the evaluation of selected types of sensor, actuator and control systems, the assessment of these devices against baseline aircraft configurations and the evaluation of the most promising technologies in a medium/large scale wind tunnel test. Figure 1 – AVERT F15 model with end plates (basic 2D setup) The considered flow control technologies are focussed on low-speed applications, mainly investigations with AFC for standard (e.g. DLR F15) and non-standard (e.g. ONERA DND A310) high-lift configurations. Several technologies are investigated and developed INCAS BULLETIN No. 2/ 2009 122 DOI: 10.13111/2066-8201.2009.1.2.17 through both numerical simulations and experiments in wind tunnel. INCAS activities are related to separation control by flap gap oscillatory blowing on a high lift configuration. A high-lift, 2-D model geometry suitable for the application of oscillatory blowing in the flap gap has been selected from previous investigations (DLR F15 model) and manufactured from new at INCAS (Figure 1). A number of test cases with different slot and blowing parameters have been investigated numerically for wind tunnel conditions by DLR. From the numerical results, recommendations for the model design were given (blowing angle and slot widths). A new F15 model has been designed and manufactured for wind tunnel testing at INCAS subsonic wind tunnel. This model was designed so that 19 TU Berlin actuators could be integrated in a 2m span model and tested in a wide range of blowing conditions for the F15 proposed geometry (Figure 2). TU Berlin has designed and manufactured dedicated actuators suitable for flap integration and flap gap oscillatory blowing experimental investigation on a high lift configuration in INCAS facility. Figure 2 – Flap setup (external view) and actuators integration Wind tunnel tests results for the selected test cases have been compared and validated against numerical results and existing experiments (with previous existing WT results at DLR for the F15 high-lift airfoil). EXPERIMENTAL SETUP The experiments in the Subsonic Wind Tunnel at INCAS have been conducted so that we could benefit from the medium size of the facility and to enable large model validation. 1. The maximum wind tunnel test room is of 2.5m width & 2 m height; the maximum permissible span of the model is aprox. 2.0m, in order to make room for end plates and to enable popper distance to the side walls of the test section. 2. In order to achieve a high Reynolds number in the range of 3 million (for wt speed close to 90 m/s), the basic chord length was selected as 600 mm. However, the basic experiments were performed at Reynolds 2 million. INCAS BULLETIN No. 2/ 2009