Abstract
The current research focuses on modeling the lift response due to dynamic (time-varying) “burst-type” actuation on a stalled airfoil. Here, the “burst-type” actuation refers to the synthetic jet (generated from the actuator) that is used for flow separation mitigation. Dynamic “burst-type” actuation exhibits two different characteristic dynamic behaviors within the system; namely, the high-frequency and low-frequency components. These characteristics introduce modeling challenges. In this paper, we propose a hybrid model composed of two individual sub-models, one for each of the two frequencies. The lift response due to high-frequency burst actuation is captured using a convolution model. The low-frequency component due to nonlinear burst-burst interactions is captured using a Wiener model, consisting of linear time-invariant dynamics and a static output nonlinearity. The hybrid model is validated using data from wind tunnel experiments.
Highlights
Unsteady flow separation causes transient aerodynamic forces in a variety of fluid dynamic applications and leads to performance degradation in many devices
The unsteady flow separation, which is an inherent phenomenon of the super maneuverability, may become the limiting factor to performance
A Wiener-convolution hybrid model was introduced and examined using a NACA 0009 airfoil with flow control actuators which were operated with open-loop forcing
Summary
Unsteady flow separation causes transient aerodynamic forces in a variety of fluid dynamic applications and leads to performance degradation in many devices. Et al [1] developed a simple linear model to predict the lift force variation associated with time-varying (transient) leading-edge actuation on a semi-circular wing. This model is achieved by averaging a family of models identified from a series of pseudo-random binary signals with different amplitudes. It is natural to investigate predictive modeling based on the complete actuation signal with both the high-frequency carrier wave and the low-frequency control signal Following this idea, Williams [1] introduced a convolution model to predict the lift variation utilizing the actuation signal.
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