Assessment of Boundary Interference in Open Test Section Wind Tunnels Using Successive Over-Relaxation

Supersonic wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiment, the stagnation pressure in the test section is required to remain constant. Due to the nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required, which is then capable of properly working under different operating conditions. In this paper, an Extended Kalman Filter (EKF) based flow control strategy is proposed and implemented in the controller. The control strategy is designed based on the state estimation of a real blowdown wind tunnel, which is carried out under an EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the controller parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

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Numerical and experimental investigations on the reduction of wind tunnel wall interference by means of adaptive slots

The Aeronautical Journal ◽

10.1017/s0001924000012513 ◽

2001 ◽

Vol 105 (1052) ◽

pp. 571-580 ◽

Cited By ~ 2

Author(s):

O. Meyer ◽

W. Nitsche ◽

I. Futterer

Keyword(s):

Wind Tunnel ◽

Test Section ◽

Wind Tunnels ◽

Experimental Investigations ◽

Reference Case ◽

Tunnel Wall ◽

Promising Alternative ◽

Model Flow ◽

Flexible Walls ◽

Basic Studies

Abstract The flow in many wind tunnel experiments is affected by the presence of test section walls. The resulting interference can be minimised by correcting the measured model pressures, or by influencing the model flow directly with the use of ventilated or adaptive test section walls. The objective behind the latter technique is to guide the flow in the test section to achieve low interference (i.e. free flow) condition at the model. The most successful technique of flexible, adaptive walls is still restricted to small research wind tunnels due to its mechanical complexity. However, a very promising alternative is the use of adaptive slots in the test section walls. This concept combines the method of passive slotted walls, as they are already implemented in many large wind tunnels, and flexible walls. Additionally, this technique presents the opportunity of full 3D adaptations because the slots can be situated in all four test section walls. This paper presents preliminary experimental results and the latest numerical calculations on the effectiveness of adaptive slots. The experiments were conducted under high subsonic flow conditions in the new slotted test section of the transonic wind tunnel at TU Berlin’s Aeronautical Institute (ILR). The numerical results presented are focussed on the 2D slot adaptation of a 2D-model (CAST7 aerofoil) and the 3D slot adaptation of a body of revolution (3D-ETB). In addition, basic studies were made of the flows associated with a single slot on one wall and a bump on the other. The numerical and the first experimental investigations have shown the potential of adaptive slots to reduce wall interferences effectively. The adaptation accuracy of the investigated slot configurations deviated not more than 3% from the reference case (2D-wall adaptation).

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Advanced Flow Control for Supersonic Blowdown Wind Tunnel Using Extended Kalman Filter

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.4028182 ◽

2014 ◽

Vol 137 (1) ◽

Cited By ~ 1

Author(s):

Jiaqi Xi ◽

Mian Li ◽

Qiang Zhang ◽

Zhaoguang Wang

Keyword(s):

Kalman Filter ◽

Flow Control ◽

Extended Kalman Filter ◽

Control Strategy ◽

Test Section ◽

Initial Conditions ◽

Stagnation Pressure ◽

Operating Conditions ◽

Wind Tunnels ◽

Wide Range

Supersonic blowdown wind tunnels provide controlled test environments for aerodynamic research on scaled models. During the experiments, the stagnation pressure in the test section is required to remain constant. Due to nonlinearity and distributed characteristics of the controlled system, a robust controller with effective flow control algorithms is required for this type of wind tunnels. In this paper, an extended Kalman filter (EKF) based flow control strategy is proposed and implemented. The control strategy is designed based on state estimation of the blowdown process under the EKF structure. One of the distinctive advantages of the proposed approach is its adaptability to a wide range of operating conditions for blowdown wind tunnels. Furthermore, it provides a systematic approach to tune the control parameters to ensure the stability of the controlled air flow. Experiments with different initial conditions and control targets have been conducted to test the applicability and performance of the designed controller. The results demonstrate that the controller and its strategies can effectively control the stagnation pressure in the test section and maintain the target pressure during the stable stage of the blowdown process.

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