Simulated Lidar Signals for Wake Vortex Detection ahead of the Aircraft

Kurzfassung

Within the DLR-project “Wetter & Fliegen“ a feasibility study of airborne lidar sensors for active control at flying through wind shear and turbulent air masses (specifically wake vortices) was carried out. The main goal of such sensors is delivering sufficiently precise real-time measurements of the wind field in a short range in front of an aircraft under clear air conditions up to cruising speed at every altitude, so that a dangerous disturbance in terms of turbulent air motion at an encounter can be alleviated by an active control system with an automatic feed-forward controller. So far, no realized lidar sensor meets the requirements with regard to accuracy, rapidity and spatial resolution of wind measurements necessary for active control. For this reason, we investigate the potential of two suited systems by means of simulations including the physical properties of lidars and atmosphere: a Fringe-Imaging(FI) Doppler Wind Lidar (DWL) similar to the one developed within the project AWIATOR and a Backscatter Lidar (BL) for wind measurements. Though a totally new optical design might be necessary for the latter device to operate at a sufficiently high spatial resolution, the signal processing offers wind components in the y- and z-directions (transversal to the aircraft’s propagation axis x) in very short time. From the results of DWL and BL simulations it turns out to be advisable to combine a Fringe-Imaging DWL for the xcomponent measurements with a BL for the y- and z-component measurements.