Aerosol Lidar Velocimeter for Shipboard Rotor Downwash Measurement

The development of a standoff sensor that can measure 3D components of wind velocity in the downwash of a rotorcraft operating near solid surfaces would enable a better understanding of this complicated flowfield and provide data to validate computational models. The goal of this research is to develop an Aerosol Lidar Velocimeter (ALV) that uses multiple near-parallel lidar beams to track the motion of atmospheric aerosol structures and extract multi-component wind data. In Phase I, the measurement requirements were analyzed and used to develop a numerical model of the performance of a prototype system. In addition, an eye safety analysis was conducted and a conceptual design of the ALV prototype was developed. Studies were conducted with a breadboard in order to demonstrate improvements in spatial and temporal resolution of the system and to obtain more data to further refine the system requirement and algorithm. In Phase II, the ALV design will be finalized and a high power, narrow-pulse laser design that we have developed for another application will be adapted and optimized for this application. The algorithm will be optimized and extended to measurements in all three dimensions using a multi-beam lidar system. At the end of the first year of Phase II, a technology demonstrator that incorporates elements of the ALV prototype will be field tested and evaluated using validation data from ultrasonic anemometers. If the demonstration is successful, the ALV prototype will be integrated and tested.