Wake Identification Based Wake Impact Alleviation Control

Abstract

During a wake vortex encounter an aircraft is exposed to strong unsteady disturbance velocities which can lead to significant changes in the aircraft attitude and flight path. This can represent a severe safety risk and can result in injuries to the passengers and crew as well as damages to the aircraft. The application of a wake impact alleviation control system can considerably decrease the aircraft’s response during the wake encounter, and hence diminish the pilot workload while reducing the potential risk to the passengers, crew, and aircraft. The realization of a wake impact alleviation controller presented here is based on a forward-looking LiDAR sensor. The information about the disturbance velocities in front of the aircraft is used to determine the control surface deflections that compensate the wake-induced disturbance moments. The novel approach of this concept is the combination of the wake impact alleviation system with a wake identification algorithm. Due to the integration of the identification algorithm it is possible to apply the wake impact alleviation with LiDAR sensors restricted to line-of-sight measurements only. In this case the LiDAR sensor only detects the flow velocity in the direction of the measurement beam. A measurement of the full velocity vector of the flow field upstream of the aircraft, which LiDAR sensors of the foreseeable future will most likely be unable to provide, is not necessary for this approach. The wake identification based wake impact alleviation is assessed for different encounter scenarios and a brief sensitivity study is performed for the most important parameters of the wake identification. It is shown that the wake impact alleviation control system significantly reduces the wake-induced attitude change of the aircraft and thus represents a promising concept to increase safety during wake vortex encounters.