A Review of Flow Control for Gust Load Alleviation

Abstract

Effective control of aerodynamic loads, such as maneuvering load and gust load, allows for reduced structural weight and therefore greater aerodynamic efficiency. After a basic introduction in the types of gusts and the current gust load control strategies for aircraft, we outline the conventional gust load alleviation techniques using trailing-edge flaps and spoilers. As these devices also function as high-lift devices or inflight speed brakes, they are often too heavy for high-frequency activations such as control surfaces. Non-conventional active control devices via fluidic actuators have attracted some attention recently from researchers to explore more effective gust load alleviation techniques against traditional flaps for future aircraft design. Research progress of flow control using fluidic actuators, including surface jet blowing and circulation control (CC) for gust load alleviation, is reviewed in detail here. Their load control capabilities in terms of lift force modulations are outlined and compared. Also reviewed are the flow control performances of these fluidic actuators under gust conditions. Experiments and numerical efforts indicated that both CC and surface jet blowing demonstrate fast response characteristics, capable for timely adaptive gust load controls.

Flow Control, Active and Passive Applications

“…A hybrid evolutionary optimization method (HCGA) in combination with a CFD solver, is presented in the work of Zhao et al [13], as a decision-maker design tool for aerodynamic shape design. The final contribution of this book was made by Li and Qin [14], who present a review of the different flow control techniques used for gust load alleviation.…”

Modelling and Control of an Urban Air Mobility Vehicle Subject to Empirically-Developed Urban Airflow Disturbances

“…These techniques use sensed information about a wind gust to adjust actuators to reduce the loads experienced by the aircraft. The oncoming gust can be sensed using, Doppler LIDAR [20,21], angle of attack sensors [22], or aircraft mounted accelerometers [23]. The gust information gathered by these sensor systems can be used with active control techniques to actuate lifting surfaces [20,24] or flow control devices [23,25] which reduce the change in aircraft lift coefficient and wing bending moments.…”

“…The oncoming gust can be sensed using, Doppler LIDAR [20,21], angle of attack sensors [22], or aircraft mounted accelerometers [23]. The gust information gathered by these sensor systems can be used with active control techniques to actuate lifting surfaces [20,24] or flow control devices [23,25] which reduce the change in aircraft lift coefficient and wing bending moments. Passive control techniques have also been demonstrated, which accomplish the same goal of alleviating gust loading to the aircraft [26].…”

“…Passive control techniques have also been demonstrated, which accomplish the same goal of alleviating gust loading to the aircraft [26]. These techniques play a crucial role in improving aircraft performance by reducing unwanted aircraft motion that can effect passenger comfort or safety and limiting structural loading which allows for the reduction of aircraft weight by reducing structural requirements [22,23]. UAM aircraft will likely encounter turbulent wind conditions that will affect aircraft performance.…”

Numerical Simulations of Vertical Discrete Gusts Driven by Trailing Edge Blowing

“…In recent years, the circulation control method has been used in many practical situations, benefiting from the precise and effective control capabilities. These situations cover not only flow control or lift enhancement [13,14] but also new applications such as flight control and load alleviation [15,16]. With the development of unsteady trailing edge blowing control methods [17], researchers designed a new type of gust generator based on the concept of circulation control, to avoid unacceptable vibration in the wind tunnel structure and achieve precise control of gust characteristics.…”