Flow Control About an Airborne Laser Turret

A high-energy laser system inflicts damage on a target by radiating large amounts of thermal energy onto a small area. Airflow about the laser turret housed on top of an aircraft is unsteady, and causes problems in beam control. These problems are jitter, which is vibration of the laser beam, and optical path distortions. The theory of flow around a cylinder and around a sphere was examined, and several airflow control techniques were investigated as possible means of suppressing the unsteadiness of the flow. A fairing and turret-base suction apparatus was selected, and was experimentally tested in a wind tunnel. During the course of the experiment, several parameters were varied, as follows blower flow rate, spacing between turret and fairing nose piece, and flow rate in five separate ducts. Results of the tests utilizing the tapered symmetric nose piece indicate that the fairing and base-suction technique eliminates the unsteadiness. Further research and testing are required to develop this technique for actual use on aircraft.