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Description
Installation of Ultra High Bypass Ratio (UHBR) turbofan engines on airframes brings significant reductions of fuel consumption and emissions. However, due to limited height of the undercarriage, UHBR engines must mounted close to wing. This results in slat cut outs at the juncture of the engine pylon, which significantly promotes separation at high angles of attack. The flow separation in this region reduces total lift of the wing at the most crucial phases of the flight mission, i.e. during take-off and landing. Therefore, mitigation of the risk related to flow separation in the slat-less area is an important research problem. Application of active flow control (AFC) has been envisioned as the most promising solution to control the flow separation at the juncture of the engine pylon. Among investigated AFC approaches, pulsed jet actuators (PJAs) provide the most promising result on a real scale Wind Tunnel (WT) model. Nevertheless, the momentum and energy consumption of a PJA system is still quite high to be implemented on an aircraft. The current work aims toward lowering the necessary energy required for separation flow control by application of advanced actuation patterns and increasing the pulse frequency while lowering the duty cycle ratios. For that purpose, a dedicated pulsed jet actuator system was developed. The design goal was to provide individual control of pulsation frequency and duty cycle at each PJA slot in the array. The paper presents results of silent condition testing of the individual actuator designed for large scale wind tunnel testing. The bench test included characterisation of high frequency pulsations of the jet by hot wire anemometer for various frequences, duty cycles input pressures and mass flow rates. The obtained results proved that the developed actuator can provide distinctive flow pulsation at high flow rates enabling high jet velocity. The results has path a way for development of 77 nozzle actuator for large scale wind tunnel model for testing power efficient flow control over large aerodynamic surface.
