Burkhard Gölling

Robust Closed-Loop Lift Control on an Industry-Relevant Civil Aircraft Half Model

This work shows the design and application of closed-loop flow control on a 1:12.6 model of an industry-relevant civil aircraft half-model wing with high-lift devices. A robust closed-loop controller was designed to control the lift generated by the airfoil. Pressure sensor data from the flap were used by the controller to drive fast solenoid valves which generate periodically pulsed jet flows into the flap flow to manipulate the separated flow. The controller was in charge of two separate segments, the in-board and out-board flap, which were actuated separately to meet a commanded lift coefficient value for the wing. By this closed-loop actuation concept, completely new flight paths are possible unseen with current technology besides the more simple delay and avoidance of separation.

Active Flow Control on an Industry-Relevant Civil Aircraft Half Model

The article presented describes an approach to active flow control by means of pulsed blowing from the flap shoulder in order to delay turbulent flow separation in low-speed flows. The experiments were carried out on an industrial low-scale high-lift wind tunnel model, a specific landing configuration model employed in the industrial aircraft design process. The results verified the concept of pulsed blowing as a suitable tool for separation control on a complex model at a Mach Number relevant for take-off and landing (Ma = 0.2) and a reasonable Reynolds Number (Re = 1.6 ·106). Lift was increased significantly over a broad range of angles of attack with only moderate energy input necessary.

Active Flow-Separation Control on a High-Lift Wing-Body Configuration

This contribution discusses the implementation of active flow-separation control for a three-dimensional high-lift wing-body configuration under atmospheric low-speed wind-tunnel conditions. The slot actuators are applied on the suction side of the trailing-edge flap to prevent local flow separation. The experimental results indicate that the pulsed blowing flow control technique is effective on the present configuration with a global performance enhancement. Numerical investigations are the focus of this article. The baseline case is characterized by substantial portions of separated flow. Thus, the influence of grid resolution and turbulence modeling is investigated. Based on this an intermediate mesh in combination with the Shear Stress Transport model gives the best compromise between quality and computational turnaround times. The steady Reynolds Averaged Navier Stokes (RANS) calculations carried out with constant blowing demonstrate the feasibility to simulate active flow control concepts. The key f...

Active Flow Separation Control on a High-Lift Wing-Body Configuration Part 2: The Pulsed Blowing Application

This contribution discusses the implementation of active flow separation control for a 3D high-lift wing-body configuration under atmospheric low-speed wind tunnel conditions. The slot-actuators are applied on the suction side of the trailing edge flap to prevent local flow separation. It is the consequent progression of the work presented in Part 1 of this paper. The active flow control (AFC) method of choice is now the pulsed blowing. The experimental results indicate that this AFC technique is feasible for such applications with a global performance enhancement. Here, the wind tunnel findings are briefly discussed while the emphasis is given on the numerical investigations. The verification of the URANS approach points out that the global enhancement through AFC may easily be overestimated by insufficient numerical convergence. Thus, high computational requirements are needed for a consistent numerical evaluation. The computational results highlight the ability of pulsed blowing at moderate blowing momentum coefficients to suppress the flow separation on the trailing edge flap and support the global aerodynamic enhancement. The numerical results show an acceptable agreement with the experimental results for this AFC application.

Active Flow Separation Control on a High-Lift Wing-Body Configuration - Part 1: Baseline Flow and Constant Blowing

This paper describes the influence of grid resolution and turbulence modeling for a 3D transport aircraft in high lift configuration with massive flap separation. The flap is equipped with spanwise slotted active flow control (AFC) devices to allow studies on active separation control. The effects of constant slotted blowing on the high lift performance are highlighted. Oil flow pictures from a mid-scale experiment in the low speed wind tunnel of Airbus in Bremen (B-LSWT) serve as a validation database for the baseline CFD results. RANS calculations are carried out with and without constant blowing boundary conditions. The baseline flow is also investigated with a time-accurate URANS approach. One of the major outcomes of the AFC study is the demonstration of the feasibility to simulate AFC concepts on a 3D configuration. Constant blowing shows the beneficial effect that separation can largely be suppressed because of the energy added to the flow on the suction side of the flap. This study serves as a preceding validation for the subsequent pulsed blowing approach treated in Part 2.