V-22 Three-Dimensional (3D) Downwash Measurement

Science and Engineering Services. Inc. (SESI) proposes to develop an Aerosol Lidar Velocimeter (ALV) to obtain concurrent three-component wind velocity measurements in the downwash of a rotorcraft operating in shipboard environments. We propose to use a multi-beam lidar system to obtain aerosol backscatter data from the flowfield and to develop a time-lag cross-correlation algorithm to extract three-component velocity measurements. In Phase I, a breadboard prototype will be designed and built to demonstrate proof-of-concept of obtaining velocity measurements from a representative flowfield and the results will be validated using sonic and cup-and-vane anemometers. This breadboard will be used to benchmark the system requirements for the design of an ALV prototype that, in Phase II, will be built and tested on a land-based full-scale test bed, with a helicopter hovering near a vertical face, subject to availability of aircraft. These measurements will be validated by comparing with anemometers and existing test data, along with computational predictions.